Abstract 
  
 Clothing treated with the pyrethroid permethrin is available in the United States as consumer products to prevent tick bites. We used tick bioassays to quantify contact irritancy and toxicity of permethrin-treated clothing for three important tick vectors of human pathogens: the blacklegged tick, Ixodes scapularis Say (Acari: Ixodidae); the lone star tick, Amblyomma americanum (L.) (Acari: Ixodidae); and the American dog tick, Dermacentor variabilis (Say) (Acari: Ixodidae). We first demonstrated that field-collected I. scapularis nymphs from Minnesota were as susceptible as laboratory-reared nymphs to a permethrin-treated textile. Field ticks examined in bioassays on the same day they were collected displayed contact irritancy by actively dislodging from a vertically oriented permethrin-treated textile, and a forced 1-min exposure resulted in all ticks being unable to move normally, thus posing no more than minimal risk of biting, 1 h after contact with the treated textile. Moreover, we documented lack of normal movement for laboratory-reared I. scapularis nymphs by 1 h after contact for 1 min with a wide range of permethrin-treated clothing, including garments made from cotton, synthetic materials, and blends. A comparison of the impact of a permethrin-treated textile across tick species and life stages revealed the strongest effect on I. scapularis nymphs (0% with normal movement 1 h after a 1-min exposure), followed by A. americanum nymphs (14.0%), I. scapularis females (38.0%), D. variabilis females (82.0%), and A. americanum females (98.0%). Loss of normal movement for all ticks 1 h after contact with the permethrin-treated textile required exposures of 1 min for I. scapularis nymphs, 2 min for A. americanum nymphs, and 5 min for female I. scapularis, D. variabilis, and A. americanum ticks. We conclude that use of permethrin-treated clothing shows promise to prevent bites by medically important ticks. Further research needs are discussed. 
  
 Numerous studies over the last four decades have shown that permethrin-treated clothing is effective against tick vectors of human pathogens in the United States, including the blacklegged tick, Ixodes scapularis Say (Acari: Ixodidae); the lone star tick, Amblyomma americanum (L.) (Acari: Ixodidae); and the American dog tick, Dermacentor variabilis (Say) (Acari: Ixodidae) (Schreck et al. 1978, 1980, 1982, 1986; Mount and Snoddy 1983; Evans et al. 1990; Miller et al. 2011; Vaughn and Meshnick 2011; Jordan et al. 2012; Vaughn et al. 2014, Eisen et al. 2017a). In addition to the use of permethrin in pressurized sprays to self-treat clothing, refined methodology for textile impregnation (Faulde and Uedelhoven 2006, Faulde et al. 2016) has led to new tick-protection consumer products in the form of permethrin-treated clothing. Insect Shield, LLC (Greensboro, NC) is a leading manufacturer of permethrin-treated clothing in the United States. In a previous study (Eisen et al. 2017a), we used material from a permethrin-treated T-shirt (100% cotton) from Insect Shield to develop a set of new bioassays to quantify contact irritancy and toxicity of permethrin-treated clothing toward nymphal I. scapularis ticks, the primary vectors in eastern North America of the causative agents of Lyme disease, anaplasmosis, and babesiosis (Eisen et al. 2017b). In addition to demonstrating contact irritancy and toxicity of the tested permethrin-treated cotton textile for I. scapularis nymphs, we observed what appeared to be a weaker contact irritant ‘hot-foot’ effect for field-collected versus laboratory-reared nymphs (Eisen et al. 2017a). However, in that study, the field-collected nymphs were held in the laboratory for ≥2 wk before being used, which may have affected their performance in the contact irritancy bioassay relative to the normal scenario of naturally host-seeking nymphs encountering permethrin-treated clothing on a human in the field. 
  
 Here, we report on a set of studies where the new bioassays were used as follows: to 1) compare the contact irritancy and toxicity of a single type of permethrin-treated clothing for laboratory-reared versus field-collected I. scapularis nymphs; 2) compare the contact irritancy and toxicity of permethrin-treated clothing made from different types of textiles for I. scapularis nymphs; and 3) compare the toxicity of a single type of permethrin-treated clothing for the primary human-biting stages of I. scapularis (nymphs and females), A. americanum (nymphs and females), and D. variabilis (females). 
  
 Materials and Methods 
  
 Sources of Permethrin-Treated Clothing and Ticks 
  
 Ten different types of permethrin-treated clothing purchased directly from Insect Shield were included in this study. Of these, three clothing items were 100% cotton (T-shirt, long sleeved shirt, and pants), three were 100% synthetic textile in the form of shirts (100% polyester shirt and 100% nylon shirt) or socks (85% coolwick/15% lycra spandex compression sock), and four were blends of cotton and synthetic textiles in the form of shirts (60% cotton/40% polyester shirt and 50% cotton/50% polyester shirt) or socks (76% cotton/21% nylon/3% lycra sock and 49% polyester/47% cotton/3% rubber/1% spandex sock). All pieces of clothing were in pristine condition (not washed or worn) when used in the bioassays. The nontreated control textile was always a 100% cotton T-shirt. Textile pieces for use in the bioassays were cut from the front or back of the shirts, the lower legs of the pants, and the upper part of socks that extend above a shoe. 
  
 Laboratory-reared ticks used in the study were obtained from the Oklahoma State University (OSU) Tick Rearing Facility (Stillwater, OK). These included I. scapularis nymphs and females, A. americanum nymphs and females, and D. variablis females, all of unknown age. Prior to being used, the ticks were held within glass desiccators (90–95% RH) in a growth chamber maintained at 21 to 22°C with a 16:8 h light:dark cycle. The lone exception was for OSU I. scapularis nymphs that were used in the field together with field-collected I. scapularis nymphs: these OSU ticks were placed in plastic desiccators equipped with water and held under ambient conditions, in the same complex where the bioassays were performed at the Camp Ripley Training Center, Morrison County, MN, for approximately 1 wk prior to being used in bioassays. Field-collected I. scapularis nymphs came from sites at the Camp Ripley Training Center. These ticks were collected from vegetation from 21 to 24 June 2017, using white cotton utility cloths as tick drags. All nymphs were used in bioassays the same day they were collected, typically within 4 h of collection. 
  
 Contact Irritancy and Toxicity Bioassays 
  
 Our vertical (45° angle) bioassay to assess contact irritancy was described in detail previously (Eisen et al. 2017a) and contains a playing card (64-mm wide by 89-mm tall) onto which a test textile is sewn. Ticks are introduced onto the center of the textile-covered card and the number remaining on the card is scored at 1-min intervals over a 5-min period. We found this bioassay to be suitable for nymphal ticks but not for the more mobile adult ticks, as these dislodged very quickly even from cards with nontreated control textile. Based on their variable mobility, we found it convenient to observe ticks within groups of 10 I. scapularis nymphs or 5 A. americanum nymphs per bioassay. After exposure, ticks were held in desiccators (90–95% RH) at room temperature in the laboratory or at ambient temperature in the field setting until scored for vigor 24 h later. Bioassays with nontreated control textile universally had survival rates of ≥90% at 24 h post-exposure. 
  
 Our bioassay to assess toxicity was described in detail previously (Eisen et al. 2017a) and is performed by keeping ticks in continuous contact with a horizontally oriented treated test textile or nontreated control material for a given period of time. In this study, we used exposure durations of 1, 2, and 5 min. Based on their variable mobility, we found it convenient to use groups of 10 I. scapularis nymphs, 5 A. americanum nymphs, or 5 female ticks of any species per bioassay. Nymphal ticks were exposed using a 10-cm diameter textile circle placed within a Petri dish, whereas the more mobile females were exposed on a larger, 18- × 13-cm piece of textile affixed within a plastic tray. After exposure, ticks were held in desiccators (90–95% RH) at room temperature in the laboratory until scored for vigor 1 and 24 h later. Bioassays with nontreated control material uniformly had survival rates of ≥90% at 24 h post-exposure. 
  
 Bioassays to compare the impact of permethrin-treated clothing made from different types of textiles were restricted to laboratory-reared I. scapularis nymphs. Bioassays to compare the impact of permethrin-treated clothing on laboratory-reared versus field-collected I. scapularis nymphs, or the primary human-biting life stages of different tick species, were restricted to a single type of permethrin-treated clothing (100% cotton). 
  
 Classification Scheme for Vigor of Ticks 
  
 We used the post-exposure classification scheme for tick vigor described previously by Eisen et al. (2017a). Briefly, tick vigor following introduction onto a nontreated surface and stimulation of activity via gentle physical prodding and human breath was scored across four categories of capacity for movement: 1) tick completely motionless; 2) tick capable of some movement of the legs but unable to right itself or walk; 3) tick capable of righting itself but not able to move in a coordinated way or readily orient toward a stimulus; and 4) tick displaying normal movement and response to a stimulus. Ticks scored as displaying normal movement (4) were further assessed to determine whether they would ascend onto a finger when given the chance. 
  
 Data Analysis 
  
 We compared proportions of ticks presenting various responses to permethrin-treated clothing to those exposed to nontreated controls using Fisher’s exact test. Results were considered significant at α = 0.05, using a one-tailed test. All comparisons were conducted in JMP Pro 13 (Cary, NC). 
  
 Results 
  
 Contact Irritancy and Toxicity of a Single Type of Permethrin-Treated Clothing for Laboratory-Reared Versus Field-Collected I. scapularis Nymphs 
  
 In the contact irritancy assay, the percentage of ticks remaining on the assay card after 1 min was significantly (P < 0.0001) lower for the permethrin-treated textile compared with the nontreated control textile, both for the laboratory-reared nymphs (57.5 and 100%, respectively) and the field-collected nymphs (32.5 and 85.0%, respectively) (Table 1). By the end of the 5-min observation period, the difference was even more pronounced for the laboratory-reared nymphs, with 100% of nymphs still on the nontreated control but only 5.0% remaining on the permethrin-treated textile (P < 0.0001). The field-collected nymphs were far more active and less likely to remain on the assay card with nontreated control textile for the full 5 min. Nevertheless, they were still marginally less likely to remain on the permethrin-treated textile compared with the nontreated control textile at the 5-min time point (7.5 and 22.5%, respectively; P = 0.0574). Moreover, the percentage of ticks displaying normal movement 24 h post-exposure was significantly (P < 0.001) reduced following contact with permethrin-treated textile compared with the nontreated control textile, both for the laboratory-reared nymphs (25.0 and 100%, respectively) and the field-collected nymphs (45.0 and 100%, respectively) (Table 1). And even fewer ticks both displayed normal movement and were willing to ascend the tip of a finger when given the opportunity (Table 1). For the field-collected nymphs, exposure to permethrin-treated textile resulted in only 17.5% both displaying normal movement and climbing onto a finger 24 h post-exposure, compared with 80.0% for exposure to nontreated control textile (P < 0.0001). 
  
 Table 1. Assay outcome Laboratory-reared nymphs Field-collected nymphs NTCa PTCb NTCa PTCb Total no. of ticks introduced onto assay card 40 40 40 40 % ticks remaining on assay card after 1 min 100 57.5 85.0 32.5 % ticks remaining on assay card after 2 min 100 42.5 47.5 22.5 % ticks remaining on assay card after 3 min 100 22.5 37.5 12.5 % ticks remaining on assay card after 4 min 100 15.0 32.5 12.5 % ticks remaining on assay card after 5 min 100 5.0 22.5 7.5 % ticks with normal movement 24 h later 100 25.0 100 45.0 % ticks both with normal movement and willing to climb a finger 24 h later 27.5 7.5 80.0 17.5 Assay outcome Laboratory-reared nymphs Field-collected nymphs NTCa PTCb NTCa PTCb Total no. of ticks introduced onto assay card 40 40 40 40 % ticks remaining on assay card after 1 min 100 57.5 85.0 32.5 % ticks remaining on assay card after 2 min 100 42.5 47.5 22.5 % ticks remaining on assay card after 3 min 100 22.5 37.5 12.5 % ticks remaining on assay card after 4 min 100 15.0 32.5 12.5 % ticks remaining on assay card after 5 min 100 5.0 22.5 7.5 % ticks with normal movement 24 h later 100 25.0 100 45.0 % ticks both with normal movement and willing to climb a finger 24 h later 27.5 7.5 80.0 17.5 View Large 
  
 Table 1. Assay outcome Laboratory-reared nymphs Field-collected nymphs NTCa PTCb NTCa PTCb Total no. of ticks introduced onto assay card 40 40 40 40 % ticks remaining on assay card after 1 min 100 57.5 85.0 32.5 % ticks remaining on assay card after 2 min 100 42.5 47.5 22.5 % ticks remaining on assay card after 3 min 100 22.5 37.5 12.5 % ticks remaining on assay card after 4 min 100 15.0 32.5 12.5 % ticks remaining on assay card after 5 min 100 5.0 22.5 7.5 % ticks with normal movement 24 h later 100 25.0 100 45.0 % ticks both with normal movement and willing to climb a finger 24 h later 27.5 7.5 80.0 17.5 Assay outcome Laboratory-reared nymphs Field-collected nymphs NTCa PTCb NTCa PTCb Total no. of ticks introduced onto assay card 40 40 40 40 % ticks remaining on assay card after 1 min 100 57.5 85.0 32.5 % ticks remaining on assay card after 2 min 100 42.5 47.5 22.5 % ticks remaining on assay card after 3 min 100 22.5 37.5 12.5 % ticks remaining on assay card after 4 min 100 15.0 32.5 12.5 % ticks remaining on assay card after 5 min 100 5.0 22.5 7.5 % ticks with normal movement 24 h later 100 25.0 100 45.0 % ticks both with normal movement and willing to climb a finger 24 h later 27.5 7.5 80.0 17.5 View Large 
  
 In the toxicity assay, continuous contact with test textile for 1 min resulted in significant (P < 0.0001) reductions (≥90 percentage points) for the probability of ticks to display normal movement after exposure to permethrin-treated textile compared with the nontreated control textile, regardless of whether we assayed laboratory-reared or field-collected nymphs and whether tick vigor was scored at 1 or 24 h post-exposure (Table 2). Of special note is that no field-collected nymphs displayed normal movement 1 h after 1-min exposure to the permethrin-treated textile, and that only 5% of nymphs having been exposed for such a brief period of time had recovered normal movement 24 h after exposure. For the field-collected nymphs, 1-min exposure to permethrin-treated textile resulted in only 2.5% both displaying normal movement and climbing onto a finger 24 h post-exposure, compared with 52.5% for exposure to nontreated control textile (P < 0.0001). 
  
 Table 2. Assay outcome Laboratory-reared nymphs Field-collected nymphs NTCa PTCb NTCa PTCb Total no. ticks exposed 40 40 40 40 % ticks with normal movement 1 h later 100 0 100 0 % ticks with normal movement 24 h later 100 7.5 95.0 5.0 % ticks both with normal movement and willing to climb a finger 24 h later 37.5 0 52.5 2.5 Assay outcome Laboratory-reared nymphs Field-collected nymphs NTCa PTCb NTCa PTCb Total no. ticks exposed 40 40 40 40 % ticks with normal movement 1 h later 100 0 100 0 % ticks with normal movement 24 h later 100 7.5 95.0 5.0 % ticks both with normal movement and willing to climb a finger 24 h later 37.5 0 52.5 2.5 View Large 
  
 Table 2. Assay outcome Laboratory-reared nymphs Field-collected nymphs NTCa PTCb NTCa PTCb Total no. ticks exposed 40 40 40 40 % ticks with normal movement 1 h later 100 0 100 0 % ticks with normal movement 24 h later 100 7.5 95.0 5.0 % ticks both with normal movement and willing to climb a finger 24 h later 37.5 0 52.5 2.5 Assay outcome Laboratory-reared nymphs Field-collected nymphs NTCa PTCb NTCa PTCb Total no. ticks exposed 40 40 40 40 % ticks with normal movement 1 h later 100 0 100 0 % ticks with normal movement 24 h later 100 7.5 95.0 5.0 % ticks both with normal movement and willing to climb a finger 24 h later 37.5 0 52.5 2.5 View Large 
  
 Contact Irritancy and Toxicity of Permethrin-Treated Clothing Made From Different Types of Textiles for Laboratory-Reared I. scapularis Nymphs 
  
 The main findings in the contact irritancy assay were that, compared with nontreated control textile, exposure to permethrin-treated textile resulted in significant reductions (P < 0.0001) in the percentage of ticks remaining on the assay card after 5 min for 9 of 10 different types of treated clothing, and in the percentage of ticks displaying normal movement 24 h post-exposure for all 10 different types of treated clothing (Table 3). Notably, the percentage of ticks displaying normal movement 24 h post-exposure was reduced to ≤20.0% for all tested types of treated clothing and to <5.0% for 6 of 10 types of treated clothing. We also note that one of the sock textiles examined—a 49% polyester/47% cotton/3% rubber/1% spandex sock—had a unique combined impact in that nymphs failed to dislodge from it but were severely affected and uniformly were unable to move normally 24 h post-exposure. 
  
 Table 3. Assay outcome Non- treated 
  
 control textile (100% cotton 
  
 T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Blends T-shirt Long sleeve 
  
 shirt Pants Polyester 
  
 long sleeve 
  
 shirt Nylon long sleeve 
  
 shirt 60% 
  
 cotton/ 
  
 40% 
  
 polyester 
  
 long 
  
 sleeve 
  
 shirt 50% 
  
 cotton/ 
  
 50% polyester 
  
 T-shirt 85% 
  
 coolwick/ 
  
 15% 
  
 lycra 
  
 sock 76% 
  
 cotton/ 
  
 21% 
  
 nylon/ 
  
 3% 
  
 lycra 
  
 sock 49% polyester/ 47% 
  
 cotton/ 
  
 3% 
  
 rubber/ 
  
 1% 
  
 spandex 
  
 sock Total no. ticks introduced onto assay card 50 50 50 50 50 50 50 50 50 50 50 % ticks remaining on assay card after 1 min 98 92 56 44 94 46 54 66 90 98 100 % ticks remaining on assay card after 2 min 98 78 22 22 76 18 22 46 70 86 96 % ticks remaining on assay card after 3 min 98 60 18 2 56 4 14 36 40 58 96 % ticks remaining on assay card after 4 min 94 44 8 2 40 0 10 28 26 40 94 % ticks remaining on assay card after 5 min 94 40 2 2 30 0 6 22 22 26 94 % ticks with normal movement 24 h later 98 0 6 2 2 14 20 0 14 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 74 0 4 0 2 8 8 0 14 0 0 Assay outcome Non- treated 
  
 control textile (100% cotton 
  
 T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Blends T-shirt Long sleeve 
  
 shirt Pants Polyester 
  
 long sleeve 
  
 shirt Nylon long sleeve 
  
 shirt 60% 
  
 cotton/ 
  
 40% 
  
 polyester 
  
 long 
  
 sleeve 
  
 shirt 50% 
  
 cotton/ 
  
 50% polyester 
  
 T-shirt 85% 
  
 coolwick/ 
  
 15% 
  
 lycra 
  
 sock 76% 
  
 cotton/ 
  
 21% 
  
 nylon/ 
  
 3% 
  
 lycra 
  
 sock 49% polyester/ 47% 
  
 cotton/ 
  
 3% 
  
 rubber/ 
  
 1% 
  
 spandex 
  
 sock Total no. ticks introduced onto assay card 50 50 50 50 50 50 50 50 50 50 50 % ticks remaining on assay card after 1 min 98 92 56 44 94 46 54 66 90 98 100 % ticks remaining on assay card after 2 min 98 78 22 22 76 18 22 46 70 86 96 % ticks remaining on assay card after 3 min 98 60 18 2 56 4 14 36 40 58 96 % ticks remaining on assay card after 4 min 94 44 8 2 40 0 10 28 26 40 94 % ticks remaining on assay card after 5 min 94 40 2 2 30 0 6 22 22 26 94 % ticks with normal movement 24 h later 98 0 6 2 2 14 20 0 14 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 74 0 4 0 2 8 8 0 14 0 0 View Large 
  
 Table 3. Assay outcome Non- treated 
  
 control textile (100% cotton 
  
 T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Blends T-shirt Long sleeve 
  
 shirt Pants Polyester 
  
 long sleeve 
  
 shirt Nylon long sleeve 
  
 shirt 60% 
  
 cotton/ 
  
 40% 
  
 polyester 
  
 long 
  
 sleeve 
  
 shirt 50% 
  
 cotton/ 
  
 50% polyester 
  
 T-shirt 85% 
  
 coolwick/ 
  
 15% 
  
 lycra 
  
 sock 76% 
  
 cotton/ 
  
 21% 
  
 nylon/ 
  
 3% 
  
 lycra 
  
 sock 49% polyester/ 47% 
  
 cotton/ 
  
 3% 
  
 rubber/ 
  
 1% 
  
 spandex 
  
 sock Total no. ticks introduced onto assay card 50 50 50 50 50 50 50 50 50 50 50 % ticks remaining on assay card after 1 min 98 92 56 44 94 46 54 66 90 98 100 % ticks remaining on assay card after 2 min 98 78 22 22 76 18 22 46 70 86 96 % ticks remaining on assay card after 3 min 98 60 18 2 56 4 14 36 40 58 96 % ticks remaining on assay card after 4 min 94 44 8 2 40 0 10 28 26 40 94 % ticks remaining on assay card after 5 min 94 40 2 2 30 0 6 22 22 26 94 % ticks with normal movement 24 h later 98 0 6 2 2 14 20 0 14 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 74 0 4 0 2 8 8 0 14 0 0 Assay outcome Non- treated 
  
 control textile (100% cotton 
  
 T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Blends T-shirt Long sleeve 
  
 shirt Pants Polyester 
  
 long sleeve 
  
 shirt Nylon long sleeve 
  
 shirt 60% 
  
 cotton/ 
  
 40% 
  
 polyester 
  
 long 
  
 sleeve 
  
 shirt 50% 
  
 cotton/ 
  
 50% polyester 
  
 T-shirt 85% 
  
 coolwick/ 
  
 15% 
  
 lycra 
  
 sock 76% 
  
 cotton/ 
  
 21% 
  
 nylon/ 
  
 3% 
  
 lycra 
  
 sock 49% polyester/ 47% 
  
 cotton/ 
  
 3% 
  
 rubber/ 
  
 1% 
  
 spandex 
  
 sock Total no. ticks introduced onto assay card 50 50 50 50 50 50 50 50 50 50 50 % ticks remaining on assay card after 1 min 98 92 56 44 94 46 54 66 90 98 100 % ticks remaining on assay card after 2 min 98 78 22 22 76 18 22 46 70 86 96 % ticks remaining on assay card after 3 min 98 60 18 2 56 4 14 36 40 58 96 % ticks remaining on assay card after 4 min 94 44 8 2 40 0 10 28 26 40 94 % ticks remaining on assay card after 5 min 94 40 2 2 30 0 6 22 22 26 94 % ticks with normal movement 24 h later 98 0 6 2 2 14 20 0 14 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 74 0 4 0 2 8 8 0 14 0 0 View Large 
  
 In the toxicity assay, a 2-min exposure led to lack of normal movement 1 and 24 h post-exposure for all ticks exposed to treated textile, regardless of the type of clothing (Table 4). This represented significant (P < 0.0001) decreases in normal movement at 1 and 24 h post-exposure for all treated textiles compared with nontreated control textile (100 and 98.0% of nymphs with normal movement, respectively). When the exposure time was reduced to 1 min, lack of normal movement for all ticks by 1 and 24 h post-exposure was still recorded for 6 of 10 types of treated textile. Exposure to the other four types of treated textile resulted in lack of normal movement for all ticks 1 h post-exposure but variable likelihood (8.0–36.0%) of recovery of normal movement by 24 h post-exposure. These results for the 1-min contact time represented significant (P < 0.0001) decreases in normal movement at 1 and 24 h post-exposure for all treated textiles compared with nontreated control textile. 
  
 Table 4. Assay outcome Non- treated 
  
 control textile (100% cotton 
  
 T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Blends T-shirt Long sleeve 
  
 shirt Pants Polyester 
  
 long sleeve 
  
 shirt Nylon long sleeve 
  
 shirt 60% 
  
 cotton/ 
  
 40% 
  
 polyester 
  
 long 
  
 sleeve 
  
 shirt 50% 
  
 cotton/ 
  
 50% polyester 
  
 T-shirt 85% 
  
 coolwick/ 
  
 15% 
  
 lycra 
  
 sock 76% 
  
 cotton/ 
  
 21% 
  
 nylon/ 
  
 3% 
  
 lycra 
  
 sock 49% polyester/ 47% 
  
 cotton/ 
  
 3% 
  
 rubber/ 
  
 1% 
  
 spandex 
  
 sock 1-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 0 0 0 0 0 0 0 0 0 % ticks with normal movement 24 h later 96 20 0 8 36 0 0 0 14 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 60 16 0 4 24 0 0 0 14 0 0 2-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 0 0 0 0 0 0 0 0 0 % ticks with normal movement 24 h later 98 0 0 0 0 0 0 0 0 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 78 0 0 0 0 0 0 0 0 0 0 Assay outcome Non- treated 
  
 control textile (100% cotton 
  
 T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Blends T-shirt Long sleeve 
  
 shirt Pants Polyester 
  
 long sleeve 
  
 shirt Nylon long sleeve 
  
 shirt 60% 
  
 cotton/ 
  
 40% 
  
 polyester 
  
 long 
  
 sleeve 
  
 shirt 50% 
  
 cotton/ 
  
 50% polyester 
  
 T-shirt 85% 
  
 coolwick/ 
  
 15% 
  
 lycra 
  
 sock 76% 
  
 cotton/ 
  
 21% 
  
 nylon/ 
  
 3% 
  
 lycra 
  
 sock 49% polyester/ 47% 
  
 cotton/ 
  
 3% 
  
 rubber/ 
  
 1% 
  
 spandex 
  
 sock 1-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 0 0 0 0 0 0 0 0 0 % ticks with normal movement 24 h later 96 20 0 8 36 0 0 0 14 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 60 16 0 4 24 0 0 0 14 0 0 2-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 0 0 0 0 0 0 0 0 0 % ticks with normal movement 24 h later 98 0 0 0 0 0 0 0 0 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 78 0 0 0 0 0 0 0 0 0 0 View Large 
  
 Table 4. Assay outcome Non- treated 
  
 control textile (100% cotton 
  
 T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Blends T-shirt Long sleeve 
  
 shirt Pants Polyester 
  
 long sleeve 
  
 shirt Nylon long sleeve 
  
 shirt 60% 
  
 cotton/ 
  
 40% 
  
 polyester 
  
 long 
  
 sleeve 
  
 shirt 50% 
  
 cotton/ 
  
 50% polyester 
  
 T-shirt 85% 
  
 coolwick/ 
  
 15% 
  
 lycra 
  
 sock 76% 
  
 cotton/ 
  
 21% 
  
 nylon/ 
  
 3% 
  
 lycra 
  
 sock 49% polyester/ 47% 
  
 cotton/ 
  
 3% 
  
 rubber/ 
  
 1% 
  
 spandex 
  
 sock 1-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 0 0 0 0 0 0 0 0 0 % ticks with normal movement 24 h later 96 20 0 8 36 0 0 0 14 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 60 16 0 4 24 0 0 0 14 0 0 2-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 0 0 0 0 0 0 0 0 0 % ticks with normal movement 24 h later 98 0 0 0 0 0 0 0 0 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 78 0 0 0 0 0 0 0 0 0 0 Assay outcome Non- treated 
  
 control textile (100% cotton 
  
 T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Blends T-shirt Long sleeve 
  
 shirt Pants Polyester 
  
 long sleeve 
  
 shirt Nylon long sleeve 
  
 shirt 60% 
  
 cotton/ 
  
 40% 
  
 polyester 
  
 long 
  
 sleeve 
  
 shirt 50% 
  
 cotton/ 
  
 50% polyester 
  
 T-shirt 85% 
  
 coolwick/ 
  
 15% 
  
 lycra 
  
 sock 76% 
  
 cotton/ 
  
 21% 
  
 nylon/ 
  
 3% 
  
 lycra 
  
 sock 49% polyester/ 47% 
  
 cotton/ 
  
 3% 
  
 rubber/ 
  
 1% 
  
 spandex 
  
 sock 1-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 0 0 0 0 0 0 0 0 0 % ticks with normal movement 24 h later 96 20 0 8 36 0 0 0 14 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 60 16 0 4 24 0 0 0 14 0 0 2-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 0 0 0 0 0 0 0 0 0 % ticks with normal movement 24 h later 98 0 0 0 0 0 0 0 0 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 78 0 0 0 0 0 0 0 0 0 0 View Large 
  
 Contact Irritancy of a Single Type of Permethrin-Treated Clothing for Laboratory-Reared Nymphal I. scapularis and A. americanum Ticks 
  
 The percentage of ticks remaining on the assay card after 1 min was significantly (P < 0.0001) lower for the permethrin-treated textile compared with the nontreated control textile, both for I. scapularis nymphs (44.0 and 98.0%, respectively) and A. americanum nymphs (6.0 and 48.0%, respectively) (Table 5). The irritant effect of the treated textile was even more pronounced for I. scapularis nymphs after the full 5-min observation period, with only 2.0% of ticks remaining on the treated textile but 94.0% remaining on the nontreated control textile (P < 0.0001). Observation periods beyond 1 min were counter-productive for the very mobile A. americanum nymphs as >80% of ticks had dislodged from the nontreated control textile already by 2 min. Most likely due to rapid dislodgement of A. americanum nymphs from the treated textile, the percentage of ticks displaying normal movement 24 h after contact was similar for those exposed to nontreated and treated clothing. By contrast, both normal movement of I. scapularis nymphs and normal movement combined with willingness to climb a finger 24 h post-exposure were significantly reduced for ticks exposed to permethrin-treated clothing compared with nontreated clothing (P < 0.0001) (Table 5). 
  
 Table 5. Assay outcome A. americanum nymphs I. scapularis nymphs NTCa PTCb NTCa PTCb Total no. of ticks introduced onto assay card 50 50 50 50 % ticks remaining on assay card after 1 min 48 6 98 44 % ticks remaining on assay card after 2 min 16 0 98 22 % ticks remaining on assay card after 3 min 8 0 98 2 % ticks remaining on assay card after 4 min 6 0 94 2 % ticks remaining on assay card after 5 min 6 0 94 2 % ticks with normal movement 24 h later 100 94 98 2 % ticks both with normal movement and willing to climb a finger 24 h later 96 94 74 0 Assay outcome A. americanum nymphs I. scapularis nymphs NTCa PTCb NTCa PTCb Total no. of ticks introduced onto assay card 50 50 50 50 % ticks remaining on assay card after 1 min 48 6 98 44 % ticks remaining on assay card after 2 min 16 0 98 22 % ticks remaining on assay card after 3 min 8 0 98 2 % ticks remaining on assay card after 4 min 6 0 94 2 % ticks remaining on assay card after 5 min 6 0 94 2 % ticks with normal movement 24 h later 100 94 98 2 % ticks both with normal movement and willing to climb a finger 24 h later 96 94 74 0 View Large 
  
 Table 5. Assay outcome A. americanum nymphs I. scapularis nymphs NTCa PTCb NTCa PTCb Total no. of ticks introduced onto assay card 50 50 50 50 % ticks remaining on assay card after 1 min 48 6 98 44 % ticks remaining on assay card after 2 min 16 0 98 22 % ticks remaining on assay card after 3 min 8 0 98 2 % ticks remaining on assay card after 4 min 6 0 94 2 % ticks remaining on assay card after 5 min 6 0 94 2 % ticks with normal movement 24 h later 100 94 98 2 % ticks both with normal movement and willing to climb a finger 24 h later 96 94 74 0 Assay outcome A. americanum nymphs I. scapularis nymphs NTCa PTCb NTCa PTCb Total no. of ticks introduced onto assay card 50 50 50 50 % ticks remaining on assay card after 1 min 48 6 98 44 % ticks remaining on assay card after 2 min 16 0 98 22 % ticks remaining on assay card after 3 min 8 0 98 2 % ticks remaining on assay card after 4 min 6 0 94 2 % ticks remaining on assay card after 5 min 6 0 94 2 % ticks with normal movement 24 h later 100 94 98 2 % ticks both with normal movement and willing to climb a finger 24 h later 96 94 74 0 View Large 
  
 Toxicity of a Single Type of Permethrin-Treated Clothing for Different Tick Species and Life Stages 
  
 Continuous exposures to treated textile revealed a general trend of decreasing sensitivity (i.e., increasing likelihood of retaining the ability to move normally 1 h post-exposure) from I. scapularis nymphs (0% with normal movement after a 1-min exposure) to A. americanum nymphs (14.0%), I. scapularis females (38.0%), D. variabilis females (82.0%), and A. americanum females (98.0%) (Table 6). Loss of normal movement for all ticks 1 h after contact with the treated textile required exposures of 1 min for I. scapularis nymphs, 2 min for A. americanum nymphs, and 5 min for female I. scapularis, D. variabilis, and A. americanum ticks. Recovery of normal movement from 1 to 24 h after contact with permethrin-treated clothing was recorded for some (8.0%) I. scapularis nymphs exposed for 1 min but not for longer (2 or 5 min) exposures. For A. americanum nymphs, 50.0–60.0% of ticks recovered normal movement from 1 to 24 h after contact that lasted for 1–2 min, compared with only 10.0% following a 5-min exposure. Patterns for females were less clear cut across the shorter contact times but for all three species we recorded recovery of females for the 5-min contact from 1 h after exposure (0% capable of normal movement for all species) to 24 h after exposure (14.0–24.0% capable of normal movement). Another interesting observation was that, in contrast to I. scapularis and A. americanum females, shorter (1–2 min) exposures for D. variabilis females appeared to result in a slow poisoning effect resulting in successive loss of normal movement over time: for example, following a 1-min exposure normal movement in the females fell from 82% 1 h later to 58% by 24 h (Table 6). 
  
 Table 6. Assay outcome Nymphs Females I. scapularis A. americanum I. scapularis A. americanum D. variabilis NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb 1-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 100 14 100 38 98 98 94 82 % ticks with normal movement 24 h later 96 8 100 74 100 44 98 96 94 58 % ticks both with normal movement and willing to climb a finger 24 h later 60 4 98 72 94 44 46 20 50 12 2-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 98 0 100 14 100 30 96 42 % ticks with normal movement 24 h later 98 0 98 52 100 22 100 48 96 20 % ticks both with normal movement and willing to climb a finger 24 h later 78 0 98 52 90 22 40 40 56 10 5-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 96 0 100 0 100 0 100 0 96 0 % ticks with normal movement 24 h later 96 0 100 10 96 20 100 24 96 14 % ticks both with normal movement and willing to climb a finger 24 h later 68 0 100 10 92 20 44 22 60 12 Assay outcome Nymphs Females I. scapularis A. americanum I. scapularis A. americanum D. variabilis NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb 1-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 100 14 100 38 98 98 94 82 % ticks with normal movement 24 h later 96 8 100 74 100 44 98 96 94 58 % ticks both with normal movement and willing to climb a finger 24 h later 60 4 98 72 94 44 46 20 50 12 2-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 98 0 100 14 100 30 96 42 % ticks with normal movement 24 h later 98 0 98 52 100 22 100 48 96 20 % ticks both with normal movement and willing to climb a finger 24 h later 78 0 98 52 90 22 40 40 56 10 5-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 96 0 100 0 100 0 100 0 96 0 % ticks with normal movement 24 h later 96 0 100 10 96 20 100 24 96 14 % ticks both with normal movement and willing to climb a finger 24 h later 68 0 100 10 92 20 44 22 60 12 View Large 
  
 Table 6. Assay outcome Nymphs Females I. scapularis A. americanum I. scapularis A. americanum D. variabilis NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb 1-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 100 14 100 38 98 98 94 82 % ticks with normal movement 24 h later 96 8 100 74 100 44 98 96 94 58 % ticks both with normal movement and willing to climb a finger 24 h later 60 4 98 72 94 44 46 20 50 12 2-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 98 0 100 14 100 30 96 42 % ticks with normal movement 24 h later 98 0 98 52 100 22 100 48 96 20 % ticks both with normal movement and willing to climb a finger 24 h later 78 0 98 52 90 22 40 40 56 10 5-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 96 0 100 0 100 0 100 0 96 0 % ticks with normal movement 24 h later 96 0 100 10 96 20 100 24 96 14 % ticks both with normal movement and willing to climb a finger 24 h later 68 0 100 10 92 20 44 22 60 12 Assay outcome Nymphs Females I. scapularis A. americanum I. scapularis A. americanum D. variabilis NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb 1-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 100 14 100 38 98 98 94 82 % ticks with normal movement 24 h later 96 8 100 74 100 44 98 96 94 58 % ticks both with normal movement and willing to climb a finger 24 h later 60 4 98 72 94 44 46 20 50 12 2-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 100 0 98 0 100 14 100 30 96 42 % ticks with normal movement 24 h later 98 0 98 52 100 22 100 48 96 20 % ticks both with normal movement and willing to climb a finger 24 h later 78 0 98 52 90 22 40 40 56 10 5-min exposure Total no. of ticks exposed 50 50 50 50 50 50 50 50 50 50 % ticks with normal movement 1 h later 96 0 100 0 100 0 100 0 96 0 % ticks with normal movement 24 h later 96 0 100 10 96 20 100 24 96 14 % ticks both with normal movement and willing to climb a finger 24 h later 68 0 100 10 92 20 44 22 60 12 View Large 
  
 Discussion 
  
 Our bioassay findings indicate that permethrin-treated clothing has promise as a personal protective measure to prevent bites by medically important ticks in the United States. This agrees with the findings of previous studies where use of permethrin-treated clothing reduced the risk of bites by I. scapularis, A. americanum, and D. variabilis under field conditions or simulated field conditions (Schreck et al. 1980, 1982, 1986; Mount and Snoddy 1983; Evans et al. 1990; Miller et al. 2011; Vaughn and Meshnick 2011; Vaughn et al. 2014). Of special note in our study is the very strong impact of permethrin-treated clothing on nymphal I. scapularis ticks, which are considered the primary vectors in the United States of seven human pathogens including the causative agents of Lyme disease, anaplasmosis, and babesiosis (Eisen et al. 2017b, Eisen and Eisen 2018). This finding is consistent with previous studies showing very high levels of protection against I. scapularis nymphs from use of permethrin-treated military uniforms (Schreck et al. 1986, Evans et al. 1990) or permethrin-treated summer-weight clothing (Miller et al. 2011). 
  
 Our side-by-side comparison of laboratory-reared and field-collected I. scapularis nymphs was prompted by a previous study where field-collected nymphs used in bioassays several weeks after collection appeared to experience contact irritancy to a lesser extent than laboratory-reared nymphs (Eisen et al. 2017a). In this study, field nymphs examined on the day of collection exhibited similarly strong contact irritancy when introduced onto permethrin-treated textile as laboratory-reared nymphs (Table 1). One possible explanation to the contradictory results for field-collected I. scapularis nymphs in the same contact irritancy bioassay in the two studies may be that a tick’s ability to engage in behavior to escape contact with the irritant substrate is related to its physiological status. In the present study, the field nymphs were used in the bioassay on the same day they were collected and, as evidenced by their high level of activity even on the nontreated control textile (Table 1), represented vigorous specimens. In the previous study where field-collected nymphs failed to display contact irritant behavior when introduced onto permethrin-treated textile (Eisen et al. 2017a), the nymphs were held in the laboratory for several weeks prior to being used and also showed a very low level of activity on nontreated control textile. We speculate that nymphal ticks in poor physiological condition may be overcome by the toxic effects of permethrin very quickly, thus rendering them unable to engage in evasive behavior that requires vigorous, coordinated movement. 
  
 Across our bioassay experiments both laboratory-reared and field-collected I. scapularis nymphs consistently lost capacity for normal movement, and thus posed no more than minimal risk of biting by 1 h after forced contact with permethrin-treated clothing for 1 min (Tables 2, 4, and 6). As also reported in our previous study (Eisen et al. 2017a), some ticks recovered capacity for normal movement by 24 h post-exposure as the effect of permethrin poisoning wore off. All examined types of permethrin-treated clothing were highly toxic to I. scapularis nymphs, regardless of whether the textile was 100% cotton, 100% synthetic material, or blends (Table 4). One intriguing finding is that although all three types of socks examined were highly toxic to the nymphs (0% ticks with normal movement 1 h after forced 1-min exposure in all three cases), a much higher proportion of ticks remained after 5 min in the vertical contact irritancy assay on one of the examined socks (94%) compared with the other two socks (22–26%). Rather than lack of contact irritancy, we speculate that this may have resulted from a looser weave and more ‘fuzzy’ surface of the sock on which ticks were less likely to dislodge, perhaps leading them to more commonly get trapped in the fibers and fail to escape the irritant textile. A previous field trial showed that A. americanum nymphs can readily stay attached to vertically oriented socks while subjects are walking (Bissinger et al. 2011). 
  
 Perhaps not surprisingly, our side-by-side comparison of different tick species and life stages showed that as ticks increase in size—from I. scapularis nymphs to A. americanum nymphs and I. scapularis, A. americanum, and D. variabilis females—a longer period of contact with permethrin-treated textile was required to achieve loss of normal movement. Nevertheless, 5-min contact was sufficient for female ticks of all species to uniformly lose their ability to move normally by 1 h post-exposure. Much remains to be explored with regards to the impact of permethrin-treated textile on different tick species and life stages, both in terms of their innate susceptibility to permethrin and their posture, which may influence their level of contact with the treated textile. For example, it stands to reason that the ventral side of the body and capitulum of a smaller tick with shorter legs more frequently would make contact with the treated textile compared with a larger tick with longer legs. Moreover, the specific escape behavior when contacting a vertical treated textile, such as a sock or pant leg, also may be important: the typical response of I. scapularis nymphs is to actively flip over and tumble downward (Eisen 2017a) leading to both their ventral and dorsal surfaces coming into contact with the treated textile. 
  
 Our study had notable limitations, most importantly that we only examined pristine permethrin-treated clothing and therefore have no data for how wearing and washing the garments may affect their contact irritancy and toxicity toward ticks. With the exception of some of the I. scapularis nymphs, the ticks used in the bioassays were reared in the laboratory and it therefore would be beneficial to confirm the results with field-collected specimens from different parts of the geographic ranges of medically important ticks. Moreover, assessing contact irritancy of permethrin-treated textiles for highly mobile female ticks will require modification of our existing bioassay as the females rapidly walked off small assay cards with nontreated control textile. Other limitations of the bioassays and tick vigor assessment were discussed previously (Eisen et al. 2017a). 
  
 Important remaining questions regarding the potential for permethrin-treated clothing to protect against bites by vector ticks and ultimately reduce tick-borne disease include the following: 1) potential loss of effectiveness following repeated wear and washing, as observed for mosquito vectors (DeRaedt Banks et al. 2015, Faulde et al. 2016, Orsborne et al. 2016, Kittayapong et al. 2017, Richards et al. 2017); 2) the level of acceptance for use of permethrin-treated clothing (Richards et al. 2014); and 3) the willingness of individuals to change their behavior by consistently putting on permethrin-treated clothing when entering tick habitat (Vaughn et al. 2014), especially if this includes parts of your own backyard and requires daily action. We also need to better understand which portions of the body must be covered by permethrin-treated clothing to achieve strong protection against tick species with different host-seeking strategies. For example, treated shoes or socks alone may be reasonably effective against mobile ‘hunter’ ticks capable of making contact with humans by actively seeking out their lower extremities when they stand still. However, more extensive coverage by permethrin-treated garments may be required to protect against ticks that rather use an ambush strategy and essentially wait for hosts to contact them, such as nymphs of I. scapularis and the closely related Ixodes pacificus Cooley and Kohls (Acari: Ixodidae). Humans greatly increase the risk for contact with nymphs of these species when picking up things from the ground (ticks getting onto hands and arms) or kneeling or sitting on the ground or natural features such as logs (ticks getting onto the legs) rather than simply walking through the environment (Carroll and Kramer 2001, Lane et al. 2004). Consequently, adequate protection against bites by nymphal I. scapularis ticks may require wearing not only permethrin-treated shoes/socks but also permethrin-treated full-length pants and long-sleeved shirts. 
  
 Acknowledgments 
  
 We thank Adam Thompson (Camp Ripley Training Center) for assistance with the field logistics. The findings and conclusions of this study are by the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention. 
  
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 Bissinger , B. W. C. S. Apperson D. W. Watson C. Arellano D. E. Sonenshine R. M. Roe , and 2011 . Novel field assays and the comparative repellency of BioUD(®), DEET and permethrin against Amblyomma americanum . Med. Vet. Entomol . 25 : 217 – 226 . Carroll , J. F. M. Kramer , and 2001 . Different activities and footwear influence exposure to host-seeking nymphs of Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae) . J. Med. Entomol . 38 : 596 – 600 . DeRaedt Banks , S. J. Orsborne S. A. Gezan H. Kaur A. Wilder-Smith S. W. Lindsey J. G. Logan , and 2015 . Permethrin-treated clothing as protection against the dengue vector, Aedes aegypti: extent and duration of protection . Plos Negl. Trop. Dis . 9 : e0004109 . Eisen , R. J. L. Eisen , and 2018 . The blacklegged tick, Ixodes scapularis: an increasing public health concern . Trends Parasitol . 34 : 295–309. : 295–309. Eisen , L. D. Rose R. Prose N. E. Breuner M. C. Dolan K. Thompson N. Connally , and 2017a . Bioassays to evaluate non-contact spatial repellency, contact irritancy, and acute toxicity of permethrin-treated clothing against nymphal Ixodes scapularis ticks . Ticks Tick. Borne. Dis . 8 : 837 – 849 . Eisen , R. J. K. J. Kugeler L. Eisen C. B. Beard C. D. Paddock , and 2017b . Tick-borne zoonoses in the United States: persistent and emerging threats to human health . ILAR J . 58 : 319–335. : 319–335. Evans , S. R. G. W. Korch , Jr , Jr M. A. Lawson , and 1990 . Comparative field evaluation of permethrin and deet-treated military uniforms for personal protection against ticks (Acari) . J. Med. Entomol . 27 : 829 – 834 . Faulde , M. W. Uedelhoven , and 2006 . A new clothing impregnation method for personal protection against ticks and biting insects . Int. J. Med. Microbiol . 296 ( Suppl 40 ): 225 – 229 . ): Faulde , M. K. F. Pages W. Uedelhoven , and 2016 . Bioactivity and laundering resistance of five commercially available, factory-treated permethrin-impregnated fabrics for the prevention of mosquito-borne diseases: the need for a standardized testing and licensing procedure . Parasitol. Res . 115 : 1573 – 1582 . Jordan , R. A. T. L. Schulze M. C. Dolan , and 2012 . Efficacy of plant-derived and synthetic compounds on clothing as repellents against Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae) . J. Med. Entomol . 49 : 101 – 106 . Kittayapong , P. P. Olanratmanee P. Maskhao P. Byass J. Logan Y. Tozan V. Louis D. J. Gubler A. Wilder-Smith , and 2017 . Mitigating diseases transmitted by Aedes mosquitoes: a cluster-randomised trial of permethrin-impregnated school uniforms . Plos Negl. Trop. Dis . 11 : e0005197 . Lane , R. S. D. B. Steinlein J. Mun , and 2004 . Human behaviors elevating exposure to Ixodes pacificus (Acari: Ixodidae) nymphs and their associated bacterial zoonotic agents in a hardwood forest . J. Med. Entomol . 41 : 239 – 248 . Miller , N. J. E. E. Rainone M. C. Dyer M. L. González T. N. Mather , and 2011 . Tick bite protection with permethrin-treated summer-weight clothing . J. Med. Entomol . 48 : 327 – 333 . Mount , G. A. E. L. Snoddy , and 1983 . Pressurized sprays of permethrin and deet on clothing for personal protection against the lone star tick and the American dog tick (Acari: Ixodidae) . J. Econ. Entomol . 76 : 529 – 531 . Orsborne , J. S. DeRaedt Banks A. Hendy S. A. Gezan H. Kaur A. Wilder-Smith S. W. Lindsay J. G. Logan , and 2016 . Personal protection of permethrin-treated clothing against Aedes aegypti, the vector of dengue and zika virus, in the laboratory . Plos One 11 : e0152805 . Richards , S. L. J. A. G. Balanay J. W. Harris , and 2014 . Effectiveness of permethrin-treated clothing to prevent tick exposure in foresters in the central Appalachian region of the USA . Int. J. Environ. Health Res . 25 : 453 – 462 . Richards , S. L. J. A. G. Balanay J. W. Harris V. M. Banks S. Meshnick , and 2017 . Residual effectiveness of permethrin-treated clothing for prevention of mosquito bites under simulated conditions . J. Environ. Health . 79 : 8 – 15 . Schreck , C. E. K. Posey D. Smith , and 1978 . Durability of permethrin as a potential clothing treatment to protect against blood-feeding arthropods . J. Econ. Entomol . 71 : 397 – 400 . Schreck , C. E. E. L. Snoddy G. A. Mount , and 1980 . Permethrin and repellents as clothing impregnants for protection from the lone star tick . J. Econ. Entomol . 73 : 436 – 439 . Schreck , C. E. G. A. Mount D. A. Carlson , and 1982 . Pressurized sprays of permethrin on clothing for personal protection against the lone star tick (Acari: Ixodidae) . J. Econ. Entomol . 75 : 1059 – 1061 . Schreck , C. E. E. L. Snoddy A. Spielman , and 1986 . Pressurized sprays of permethrin or deet on military clothing for personal protection against Ixodes dammini (Acari: Ixodidae) . J. Med. Entomol . 23 : 396 – 399 . Vaughn , M. F. S. R. Meshnick , and 2011 . Pilot study assessing the effectiveness of long-lasting permethrin-impregnated clothing for the prevention of tick bites . Vector Borne Zoonotic Dis . 11 : 869 – 875 . Vaughn , M. F. S. W. Funkhouser F. C. Lin J. Fine J. J. Juliano C. S. Apperson S. R. Meshnick , and 2014 . Long-lasting permethrin impregnated uniforms: a randomized-controlled trial for tick bite prevention . Am. J. Prev. Med . 46 : 473 – 480 . 
  
 Published by Oxford University Press on behalf of Entomological Society of America 2018. ||||| Scientists at the Centers for Disease Control and Prevention (CDC) think they can fight the scourge of tick-borne diseases by encouraging people to douse their clothes in a chemical called permethrin. 
  
 In a new study, published today (May 24) in the Journal of Medical Entomology, researchers showed that permethrin-treated clothes can seriously mess up a tick's stride. Stick some adult ticks on a pair of regular pants tilted at a 45-degree angle, and 100 percent of them will still be clinging on 5 minutes later. Stick adult ticks on a pair of tilted pants treated with permethrin, though, and 42.5 percent will tumble off entirely. Even those that remain get seriously messed up. The researchers found that only 25 percent of the ticks were moving normally even 24 hours after exposure. 
  
 "All tested tick species and life stages experienced irritation, the 'hot-foot' effect, after coming into contact with permethrin-treated clothing," Lars Eisen, a CDC entomologist who worked on the study, said in a statement. 
  
 Permethrin isn't a new chemical. You can already buy clothes coated in the stuff, which one manufacturer markets as repelling "mosquitoes, ticks, ants, flies, chiggers and midges" and persisting on the clothes through at least 70 rounds in the washing machine. Drugs.com recommends it as a treatment for lice and scabies, and states that it's not known to be toxic to humans — though it can cause some mild irritation in some people. 
  
 Researchers said in the paper that it's still not known how long permethrin remains effective in clothing, because all the clothes they tested were "pristine" and freshly treated. But these results do suggest real benefits to permethrin-treated socks, pants and other clothes, they said. 
  
 Ticks are responsible for a number of serious diseases, as Live Science has previously reported, including Lyme disease. And their range appears to be spreading, likely due to climate change . That means that, for scientists at the CDC, the project of stopping them is ever more urgent. 
  
 Originally published on Live Science. |||||

Write a summary.
– In an especially nasty year for ticks, the US Centers for Disease Control and Prevention has issued a statement about a possible method for preventing the spread of diseases carried by their bites, Live Science reports. By spraying clothing with an insecticide called permethrin, experts believe you can cause the bugs to get so-called "hot feet" and fall off before transmitting germs that cause Lyme and other tick-borne diseases like Rocky Mountain spotted fever. According to a study published in the Entomological Society of America's Journal of Medical Entomology, permethrin caused ticks of multiple species to fall off clothing and, after prolonged exposure, caused their movements to become uncoordinated. The findings are more solid evidence that covering up with clothing and applying insecticide are two vital steps to preventing tick-borne illness. Meanwhile, the number of Americans catching diseases from tiny bloodsucking creatures is going up at an alarming rate, federal authorities warn. According to the latest report from the CDC, the number of reported illnesses caused by ticks, mosquitoes, and fleas more than tripled between 2004 and 2016—and since many illnesses go unreported, the true total is probably much higher than the 642,602 cases reported over the period. In the case of Lyme disease, the number of illnesses may be up to 10 times the 36,429 cases the CDC recorded for 2016, the Washington Post reports. Analysts say other such diseases—including recently discovered ones like Powassan virus—are on the rise in the Northeast, California, and the upper Midwest and partially blame warmer weather, which is causing longer tick seasons and expanded insect ranges.
Abstrakt Kläder som behandlas med pyretroiden permetrin finns i USA som konsumentprodukter för att förhindra fästingbett. Vi använde fästing bioassays för att kvantifiera kontaktirritans och toxicitet av permetrin-behandlade kläder för tre viktiga fästing vektorer av mänskliga patogener: den svartbenta fästingen, Ixodes scapularis Say (Acari: Ixodidae); den ensamma stjärna fästingen, Amblyomma americanum (L.) (Acari: Ixodidae); och den amerikanska hund fästingen, Dermacentor variabilis (Say) (Acari: Ixodidae). Vi visade först att fältsamlade I. scapularisnymfer från Minnesota var lika mottagliga som laboratorieuppfostrade nymfer för en permetrinbehandlad textil. Fältfästingar som undersöktes i bioassayer samma dag som de samlades in visades kontaktirritans genom att aktivt lossna från en vertikalt orienterad permetrinbehandlad textil, och en tvångsexponering på 1 min resulterade i att alla fästingar inte kunde röra sig normalt, vilket inte innebar mer än minimal risk för bitning, 1 timme efter kontakt med den behandlade textilen. Dessutom har vi dokumenterat brist på normal rörelse för laboratorieuppfostrade I. scapularis nymfer med 1 timme efter kontakt i 1 min med ett brett utbud av permetrinbehandlade kläder, inklusive plagg tillverkade av bomull, syntetiska material, och blandningar. En jämförelse av inverkan av en permetrinbehandlad textil över fästingar och livsstadier visade den starkaste effekten på I. scapularis nymfer (0 % med normal rörelse 1 timme efter en 1-mins exponering), följt av A. americanum nymfer (14,0 %), I. scapularis honor (38,0 %), D. variabilis honor (82,0 %) och A. americanum honor (98,0 %). Förlust av normal rörelse för alla fästingar 1 timme efter kontakt med den permetrinbehandlade textilen krävde exponeringar på 1 min för I. scapularis nymfer, 2 min för A. americanum nymfer, och 5 min för kvinnliga I. scapularis, D. variabilis, och A. americanum fästingar. Vi drar slutsatsen att användningen av permetrin-behandlade kläder visar löfte om att förhindra bett av medicinskt viktiga fästingar. Ytterligare forskningsbehov diskuteras. Många studier under de senaste fyra decennierna har visat att permetrinbehandlade kläder är effektiva mot fästingvektorer av mänskliga patogener i USA, däribland den svartbenta fästingen, Ixodes scapularis Say (Acari: Ixodidae); den ensamma stjärnfästingen, Amblyomma americanum (L.) (Acari: Ixodidae); och den amerikanska hundfästingen, Dermacentor variabilis (Say) (Acari: Ixodidae) (Schreck et al. 1978, 1980, 1982, 1986; Mount and Snoddy 1983; Evans et al. 1990; Miller m.fl. 2011; Vaughn and Meshnick 2011; Jordan m.fl. 2012; Vaughn m.fl. 2014, Eisen et al. 2017a). Utöver användningen av permetrin i trycksatta sprayer för att själv behandla kläder, förfinad metodik för textilimpregnering (Faulle och Uedelhoven 2006, Faulde et al. 2016) har lett till nya fästingskyddande konsumentprodukter i form av permetrinbehandlade kläder. Insect Shield, LLC (Greensboro, NC) är en ledande tillverkare av permetrinbehandlade kläder i USA. I en tidigare studie (Eisen m.fl. 2017a), använde vi material från en permetrin-behandlad T-shirt (100% bomull) från Insect Shield för att utveckla en uppsättning nya bioassays för att kvantifiera kontaktirritans och toxicitet av permetrin-behandlade kläder mot nymphal I. scapularis fästingar, de primära vektorerna i östra Nordamerika av de orsakande medlen för borrelia, anaplasmos, och babesios (Eisen et al. 2017b). Förutom att påvisa kontaktirritans och toxicitet hos den testade permetrinbehandlade bomullstextilen för I. scapularis-nymfer, observerade vi vad som verkade vara en svagare kontaktirriterande ”varmfot” effekt för fältsamlade kontra laboratorieuppfödda nymfer (Eisen et al. 2017a). I den studien hölls dock de fältsamlade nymferna i laboratoriet under ≥2 wk innan de användes, vilket kan ha påverkat deras prestanda i kontaktretlighetsbioassay i förhållande till det normala scenariot med naturligt sökande nymfer som stöter på permetrinbehandlade kläder på en människa i fält. Här rapporterar vi om en uppsättning studier där de nya bioassayerna användes enligt följande: att 1) jämföra kontaktretlighet och toxicitet hos en enda typ av permetrinbehandlade kläder för laboratorieuppfostrade kontra fältsamlade I. scapularis nymfer, 2) jämföra kontaktretlighet och toxicitet hos permetrinbehandlade kläder tillverkade av olika typer av textilier för I. scapularis nymfer, och 3) jämföra toxiciteten hos en enda typ av permetrinbehandlade kläder för de primära humanbitande stadierna av I. scapularis (nymfer och honor), A. americanum (nymfer och honor), och D. variabilis (honor). Material och metoder Källor till Permetrin-Bearbetade kläder och fästingar Tio olika typer av permetrin-behandlade kläder som köptes direkt från Insect Shield ingick i denna studie. Av dessa var tre klädesplagg 100% bomull (T-shirt, långärmad skjorta, och byxor), tre var 100% syntetisk textil i form av skjortor (100% polyester skjorta och 100% nylon skjorta) eller strumpor (85% coolwick/15% lycra spandex kompressionssocka), och fyra var blandningar av bomull och syntetiska textilier i form av skjortor (60% bomull/40% polyester skjorta och 50% bomull/50% polyester skjorta) eller strumpor (76% bomull/21% nylon/3% lykra socka och 49% polyester/47% bomull/3% gummi/1% spandexsocka). Alla klädesplagg var i ofördärvat skick (ej tvättade eller slitna) när de användes i bioassayerna. Den obehandlade kontrolltextilen var alltid en 100% bomull T-shirt. Textilbitar för användning i bioassayerna skars från skjortornas fram- eller baksida, byxornas underben och den övre delen av strumpor som sträcker sig ovanför en sko. De fästingar som användes i studien togs från Oklahoma State University (OSU) Tick Rearing Facility (Stillwater, OK). Dessa inkluderade I. scapularis nymfer och honor, A. americanum nymfer och honor, och D. variablis honor, alla av okänd ålder. Innan fästingarna användes hölls de inom glasexsickatorer (90–95 % RH) i en tillväxtkammare som hölls vid 21 till 22°C med en 16:8 h ljus:mörk cykel. Det enda undantaget var för OSU I. scapularis-nymfer som användes i fält tillsammans med fältsamlade I. scapularis-nymfer: dessa OSU-fästingar placerades i plastexsickatorer utrustade med vatten och hölls under omgivande förhållanden, i samma komplex där bioassayerna utfördes på Camp Ripley Training Center, Morrison County, MN, för cirka 1 wk innan de användes i bioassayer. Fältsamlade I. scapularisnymfer kom från platser vid Camp Ripley Training Center. Dessa fästingar hämtades från vegetationen 21–24 juni 2017, med hjälp av vit bomulls nyttoduk som fästingdrag. Alla nymfer användes i bioassayer samma dag som de samlades in, typiskt inom 4 timmar efter insamlingen. Kontakt Irritans och toxicitet Bioassays Vår vertikala (45° vinkel) bioassay för att bedöma kontaktirritans beskrevs i detalj tidigare (Eisen et al. 2017a) och innehåller ett spelkort (64-mm brett av 89-mm högt) på vilket en provtextil sys. Fästingar införs på mitten av det textiltäckta kortet och det antal som återstår på kortet poängsätts med 1-minsintervall under en 5-minsperiod. Vi fann att denna bioassay var lämplig för nymfala fästingar men inte för de mer rörliga vuxna fästingarna, eftersom dessa lossnade mycket snabbt även från kort med icke behandlad kontrolltextil. Baserat på deras varierande rörlighet, fann vi det bekvämt att observera fästingar inom grupper om 10 I. scapularis nymfer eller 5 A. americanum nymfer per bioassay. Efter exponering hölls fästingar i exsickatorer (90–95 % RH) i rumstemperatur i laboratoriet eller vid omgivande temperatur i fältinställningen tills de fick resultat för vigör 24 timmar senare. Bioassays med icke behandlad textil hade överlevnadsfrekvenser på ≥90% vid 24 timmar efter exponering. Vår bioassay för att bedöma toxicitet beskrevs i detalj tidigare (Eisen et al. 2017a) och utförs genom att fästingar hålls i kontinuerlig kontakt med ett horisontellt behandlat testtextil- eller icke-behandlat kontrollmaterial under en given tidsperiod. I denna studie använde vi exponeringstiderna 1, 2 och 5 min. Baserat på deras varierande rörlighet, fann vi det lämpligt att använda grupper av 10 I. scapularis nymfer, 5 A. americanum nymfer, eller 5 kvinnliga fästingar av någon art per bioassay. Nymphal fästingar exponerades med hjälp av en textilcirkel med 10 cm diameter placerad i en Petri skål, medan de mer rörliga honorna exponerades på en större, 18 × 13 cm stor textilbit som satt fast i en plastbricka. Efter exponering hölls fästingar i exsickatorer (90–95 % RH) i rumstemperatur i laboratoriet tills de fick poäng för vigör 1 och 24 timmar senare. Bioassay med icke-behandlat kontrollmaterial hade en överlevnadsgrad på ≥90 % vid 24 timmar efter exponering. Bioassays för att jämföra effekten av permetrinbehandlade kläder tillverkade av olika typer av textilier begränsades till laboratorieuppfostrade I. scapularis-nymfer. Bioassays för att jämföra inverkan av permetrinbehandlade kläder på laboratorieuppfostrade kontra fältsamlade I. scapularis-nymfer, eller de primära humanbitande livsstadierna hos olika fästingar, begränsades till en enda typ av permetrinbehandlade kläder (100 % bomull). Klassificeringsschema för fästingars vigör Vi använde klassificeringsschemat efter exponering för fästingars vigör som beskrevs tidigare av Eisen et al. (2017a). Kort sagt, fästing vigor efter introduktion på en icke behandlad yta och stimulans av aktivitet via mild fysisk prodding och mänsklig andedräkt gjordes över fyra kategorier av rörelseförmåga: 1) fästing helt orörlig; 2) fästing som kan någon rörelse av benen men inte kan räta sig eller gå; 3) fästing som kan räta ut sig själv men inte kan röra sig på ett samordnat sätt eller lätt orientera sig mot en stimulans; och 4) fästing som visar normal rörelse och respons på en stimulans. Fästingar som gjordes för att visa normal rörelse (4) bedömdes vidare för att avgöra om de skulle stiga upp på ett finger när de fick chansen. Dataanalys Vi jämförde proportioner av fästingar som presenterade olika svar på permetrinbehandlade kläder med dem som exponerats för icke-behandlade kontroller med hjälp av Fishers exakta test. Resultaten ansågs signifikanta vid α = 0,05, med ett ensvanstest. Alla jämförelser gjordes i JMP Pro 13 (Cary, NC). Resultat Kontakt Irritans och toxicitet hos en enda typ av Permetrin-Bearbetad Kläder för laboratorieuppfostrade Versus Field-Collected I. scapularis Nymfer I kontaktanalysen var andelen fästingar som fanns kvar på analyskortet efter 1 min signifikant (P < 0,0001) lägre för permetrin-behandlade textilier jämfört med den icke-behandlade kontrolltextilen, både för laboratorieuppfostrade nymfer (57,5 respektive 100%) och fältsamlade nymfer (32,5 respektive 85,0 %) (tabell 1). Vid slutet av observationsperioden på 5 minuter var skillnaden ännu mer uttalad för de laboratorieuppfostrade nymferna, med 100% av nymferna fortfarande på den icke-behandlade kontrollen men endast 5,0% kvar på den permetrinbehandlade textilen (P < 0,0001). De fältsamlade nymferna var betydligt aktivare och hade mindre sannolikhet att finnas kvar på analyskortet med icke behandlad kontrolltextil under hela 5 minuter. Trots detta var det fortfarande marginellt mindre sannolikt att de fanns kvar på den permetrinbehandlade textilen jämfört med den icke behandlade kontrolltextilen vid 5-minutspunkten (7,5 respektive 22,5 %; P = 0,0574). Dessutom minskade andelen fästingar som uppvisade normal rörelse 24 timmar efter exponering signifikant (P < 0,001) efter kontakt med permetrinbehandlade textilier jämfört med den icke behandlade kontrolltextilen, både för de laboratorieuppfödda nymferna (25,0 respektive 100%) och de fältsamlade nymferna (45,0 respektive 100%) (tabell 1). Och ännu färre fästingar visade både normal rörelse och var villiga att lyfta fingerspetsen när man fick möjlighet (tabell 1). För de fältsamlade nymferna resulterade exponeringen för permetrinbehandlad textil i att endast 17,5 % både visade normal rörelse och klättrade upp på ett finger 24 timmar efter exponering, jämfört med 80,0 % för exponering för icke behandlad kontrolltextil (P < 0,0001). Tabell 1. Analysresultat Nymfer från laboratoriet Fältsamlade nymfer NTCa PTCb NTCa PTCb Totalt nr. Av fästingar som förts in på analyskort 40 40 40 % fästingar kvar på analyskort efter 1 min 100 57,5 85,0 32,5 % fästingar kvar på analyskort efter 2 min 100 42,5 47,5 22,5 % fästingar kvar på analyskort efter 3 min 100 22,5 37,5 12,5 % fästingar kvar på analyskort efter 4 min 100 15,0 32,5 12,5 % fästingar kvar på analyskort efter 5 min 100 5,0 22,5 7,5 % fästingar med normal rörelse 24 timmar senare 100 25,0 100 45,0 % fästingar både med normal rörelse och villiga att klättra upp på ett finger 24 timmar senare 27,5 7,5 80,0 17,5 Resultat Laboratoriska uppfödda nymfer Fältsamlade nymfer NTCa PTCb NTCa PTCb Totalt nr. av fästingar som förts in på analyskort 40 40 40 % fästingar kvar på analyskort efter 1 min 100 57,5 85,0 32,5 % fästingar kvar på analyskort efter 2 min 100 42,5 47,5 22,5 % fästingar kvar på analyskort efter 3 min 100 22,5 37,5 12,5 % fästingar kvar på analyskort efter 4 min 100 15,0 32,5 12,5 % fästingar kvar på analyskort efter 5 min 100 5,0 22,5 7,5 % fästingar med normal rörelse 24 timmar senare 100 25,0 100 45,0 % fästingar både med normal rörelse och villiga att klättra upp på ett finger 24 timmar senare 27,5 7,5 80,0 17,5 Visa Stor tabell 1. Analysresultat Nymfer från laboratoriet Fältsamlade nymfer NTCa PTCb NTCa PTCb Totalt nr. Av fästingar som förts in på analyskort 40 40 40 % fästingar kvar på analyskort efter 1 min 100 57,5 85,0 32,5 % fästingar kvar på analyskort efter 2 min 100 42,5 47,5 22,5 % fästingar kvar på analyskort efter 3 min 100 22,5 37,5 12,5 % fästingar kvar på analyskort efter 4 min 100 15,0 32,5 12,5 % fästingar kvar på analyskort efter 5 min 100 5,0 22,5 7,5 % fästingar med normal rörelse 24 timmar senare 100 25,0 100 45,0 % fästingar både med normal rörelse och villiga att klättra upp på ett finger 24 timmar senare 27,5 7,5 80,0 17,5 Resultat Laboratoriska uppfödda nymfer Fältsamlade nymfer NTCa PTCb NTCa PTCb Totalt nr. Om fästingar som förts in på analyskort 40 40 40 % fästingar kvar på analyskort efter 1 min 100 57,5 85,0 32,5 % fästingar kvar på analyskort efter 2 min 100 42,5 47,5 22,5 % fästingar kvar på analyskort efter 3 min 100 22,5 37,5 12,5 % fästingar kvar på analyskort efter 4 min 100 15,0 32,5 12,5 % fästingar kvar på analyskort efter 5 min 100 5,0 22,5 % fästingar med normal rörelse 24 timmar senare 100 25,0 100 45,0 % fästingar både med normal rörelse och villiga att klättra på ett finger 24 timmar senare 27,5 7,5 80,0 17,5 Visa stort I toxicitetstestet resulterade kontinuerlig kontakt med testtextil under 1 min i betydande (P < 0,0001) minskningar (≥90 procentenheter) för sannolikheten för fästingar att visa normal rörelse efter exponering för permetrinbehandlad textil jämfört med den icke behandlade kontrolltextilen, oavsett om vi analyserade laboratorieuppfödda eller fältsamlade nymfer och huruvida fästingar gjordes vid 1 eller 24 h efter . Särskilt viktigt är att inga fältsamlade nymfer uppvisade normal rörelse 1 timme efter 1-min exponering för den permetrinbehandlade textilen, och att endast 5 % av nymferna som hade exponerats under en så kort tidsperiod hade återhämtat sig normal rörelse 24 timmar efter exponering. För de fältsamlade nymferna resulterade 1-minsexponering för permetrinbehandlad textil i att endast 2,5 % både visade normal rörelse och klättrade upp på ett finger 24 timmar efter exponering, jämfört med 52,5 % för exponering för icke behandlad kontrolltextil (P < 0,0001). Tabell 2. Analysresultat Nymfer från laboratoriet Fältsamlade nymfer NTCa PTCb NTCa PTCb Totalt nr. fästingar exponerade 40 40 40 40 % fästingar med normal rörelse 1 timme senare 100 0 100 0 % fästingar med normal rörelse 24 timmar senare 100 7,5 95,0 5,0 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 37,5 0 52,5 Utfall från laboratorieuppfostrade nymfer Fältsamlade nymfer NTCa PTCb NTCa PTCb Totalt nr. fästingar exponerade 40 40 40 40 % fästingar med normal rörelse 1 timme senare 100 0 100 0 % fästingar med normal rörelse 24 timmar senare 100 7,5 95,0 5,0 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 37,5 0 52,5 2,5 Visa stort bord 2. Analysresultat Nymfer från laboratoriet Fältsamlade nymfer NTCa PTCb NTCa PTCb Totalt nr. fästingar exponerade 40 40 40 40 % fästingar med normal rörelse 1 timme senare 100 0 100 0 % fästingar med normal rörelse 24 timmar senare 100 7,5 95,0 5,0 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 37,5 0 52,5 Utfall från laboratorieuppfostrade nymfer Fältsamlade nymfer NTCa PTCb NTCa PTCb Totalt nr. fästingar exponerade 40 40 40 40 % fästingar med normal rörelse 1 timme senare 100 0 100 0 % fästingar med normal rörelse 24 timmar senare 100 7,5 95,0 5,0 % fästingar både med normal rörelse och villiga att klättra på ett finger 24 timmar senare 37,5 0 52,5 Visa stora kontaktirritans och toxicitet av Permetrin-Bearbetade kläder tillverkade av olika typer av textilier för Laboratory-Reared I. scapularis Nymfs De viktigaste resultaten i kontaktrettansanalysen var att exponering för permetrin-behandlade textilier, jämfört med icke-behandlade kontrolltextilier, resulterade i betydande minskningar (P < 0,0001) av andelen fästingar kvar på analyskortet efter 5 minuter för 9 av 10 olika typer av behandlade kläder, och i procent av fästingar som visade normal rörelse 24 timmar efter exponering för alla 10 olika typer av behandlade kläder (tabell 3). I synnerhet minskades andelen fästingar som uppvisade normal rörelse 24 timmar efter exponering till ≤ 20,0 % för alla testade typer av behandlade kläder och till < 5,0 % för 6 av 10 typer av behandlade kläder. Vi noterar också att en av de strumptextilier som undersöktes – en 49% polyester/47% bomull/3% gummi/1% spandexsocka – hade en unik kombinerad effekt i och med att nymfer inte lyckades lossna från den men var allvarligt påverkade och enhetligt inte kunde röra sig normalt 24 timmar efter exponering. Tabell 3. Resultat Icke-behandlad kontroll textil (100% bomull T-shirt) Permetrinbehandlade textilier 100% bomull 100% syntetiska Blandningar T-shirt Långärmad skjorta Polyester långärmad skjorta Nylon långärmad skjorta 60% bomull/ 40% polyester långärmad skjorta 50% bomull/ 50% polyester T-shirt 85% coolwick/ 15% lycrasocka 76% bomull/ 21% nylon/ 3% lycrasocka 49% polyester/ 47% bomull/ 3% gummi/ 1% spandexsocka Totalt nr. T-shirt Långärmad skjorta Långärmad skjorta Nylon långärmad skjorta 60% bomull/ 40% polyester 50% bomull/ 50% bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % fästingar kvar på analyskort efter 1 min 98 92 56 56 94 46 54 66 90 98 100 % fästingar kvar på analyskort efter 2 min 98 22 76 18 46 70 86 96 % fästingar kvar på analyskort efter 3 min 98 60 18 2 56 4 4 4 14 36 58 96 % fästingar kvar på analyskort efter 4 min 94 8 2 4 4 4 4 4 4 0 40 % fästingar kvar på analyskort efter 10 min 94 40 % 94 2 2 2 30 0 94 % fästingar kvar på analyskort efter 5 min 2 2 2 2 2 2 14 20 0 0 % fästingar både med normal rörelse och villig att klättra upp på ett finger 24 h senare 74 0 4 2 8 8 0 14 0 0 0 0 0 Resultat Icke-behandlade textiler (100 % bomull) Permetrikt tyg (100 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull Fästingar som införts på analyskort 50 50 50 50 50 50 50 50 50 50 50 % fästingar kvar på analyskort efter 1 min 98 92 56 44 94 46 54 66 90 98 100 % fästingar kvar på analyskort efter 2 min 98 78 22 76 18 22 46 70 86 96 % fästingar kvar på analyskort efter 3 min 98 60 18 2 56 4 14 36 40 58 96 % fästingar kvar på analyskort efter 4 min 94 44 8 2 40 0 10 28 26 40 94 % fästingar kvar på analyskort efter 5 min 94 40 2 2 30 0 6 22 22 26 94 % fästingar med normal rörelse 24 timmar senare 98 0 6 2 14 20 0 14 0 0 % fästingar både med normal rörelse och villig att klättra upp på ett finger 24 timmar senare 74 0 2 8 8 14 0 0 Visa Stor tabell 3. Resultat Icke-behandlad kontroll textil (100% bomull T-shirt) Permetrinbehandlade textilier 100% bomull 100% syntetiska Blandningar T-shirt Långärmad skjorta Polyester långärmad skjorta Nylon långärmad skjorta 60% bomull/ 40% polyester långärmad skjorta 50% bomull/ 50% polyester T-shirt 85% coolwick/ 15% lycrasocka 76% bomull/ 21% nylon/ 3% lycrasocka 49% polyester/ 47% bomull/ 3% gummi/ 1% spandexsocka Totalt nr. T-shirt Långärmad skjorta Långärmad skjorta Nylon långärmad skjorta 60% bomull/ 40% polyester 50% bomull/ 50% bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % fästingar kvar på analyskort efter 1 min 98 92 56 56 94 46 54 66 90 98 100 % fästingar kvar på analyskort efter 2 min 98 22 76 18 46 70 86 96 % fästingar kvar på analyskort efter 3 min 98 60 18 2 56 4 4 4 14 36 58 96 % fästingar kvar på analyskort efter 4 min 94 8 2 4 4 4 4 4 4 0 40 % fästingar kvar på analyskort efter 10 min 94 40 % 94 2 2 2 30 0 94 % fästingar kvar på analyskort efter 5 min 2 2 2 2 2 2 14 20 0 0 % fästingar både med normal rörelse och villig att klättra upp på ett finger 24 h senare 74 0 4 2 8 8 0 14 0 0 0 0 0 Resultat Icke-behandlade textiler (100 % bomull) Permetrikt tyg (100 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull/ 5 % bomull Fästingar som införts på analyskort 50 50 50 50 50 50 50 50 50 50 50 % fästingar som finns kvar på analyskort efter 1 min 98 92 56 44 94 46 54 66 90 98 100 % fästingar som finns kvar på analyskort efter 2 min 98 78 22 76 18 46 70 86 96 % fästingar som finns kvar på analyskort efter 3 min 98 60 18 2 56 4 14 36 40 58 96 % fästingar som finns kvar på analyskort efter 4 min 94 8 2 40 0 10 28 26 40 94 % fästingar som finns kvar på analyskort efter 5 min 94 40 2 2 30 0 6 22 26 94 % fästingar med normal rörelse 24 h senare 98 0 6 2 14 20 0 14 0 0 % fästingar både med normal rörelse och villiga att klättra upp på ett finger 24 h senare 74 0 2 8 14 0 0 Visa stort I toxicitetsanalysen ledde en 2-minexponering till avsaknad av normal rörelse 1 och 24 timmar efter exponering för alla fästingar som exponerades för behandlad textil, oavsett typ av kläder (tabell 4). Detta motsvarade en signifikant (P < 0,0001) minskning av normal rörelse vid 1 respektive 24 timmar efter exponering för alla behandlade textilier jämfört med icke-behandlade kontrolltextilier (100 respektive 98,0 % av nymfer med normal rörelse). När exponeringstiden minskades till 1 min registrerades fortfarande avsaknad av normal rörelse för alla fästingar med 1 och 24 timmar efter exponering för 6 av 10 typer av behandlad textil. Exponering för de övriga fyra typerna av behandlad textil resulterade i brist på normal rörelse för alla fästingar 1 timme efter exponering men variabel sannolikhet (8,0–36,0 %) för återhämtning av normal rörelse med 24 timmar efter exponering. Dessa resultat för 1-min kontakttid representerade signifikant (P < 0,0001) minskning av normal rörelse vid 1 och 24 timmar efter exponering för alla behandlade textilier jämfört med icke behandlade kontrolltextilier. Tabell 4. Resultat Icke-behandlad kontroll textil (100% bomull T-shirt) Permetrin-behandlade textilier 100% bomull 100% syntetiska Blandningar T-shirt Långärmad skjorta Polyester långärmad skjorta Nylon långärmad skjorta 60% bomull/ 40% polyester långärmad skjorta 50% bomull/ 50% polyester T-shirt 85% coolwick/ 15% lycrasocka 76% bomull/ 21% nylon/ 3% lycrasocka 49% polyester/ 47% bomull/ 3% gummi/ 1% spandexsocka 1-min exponering Totalt nr. 50 50 50 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 0 0 0 0 0 0 0 0 0 0 % fästingar med normal rörelse 24 timmar senare 96 20 0 8 36 0 0 14 0 0 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 60 16 0 4 24 0 0 0 14 0 0 2 min exponering Totalt nr. av fästingar exponerade 50 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 0 0 0 0 0 0 0 0 0 0 0 % fästingar med normal rörelse 24 timmar senare 98 0 0 0 0 0 0 0 0 0 0 % fästingar både med normal rörelse och villiga att klättra upp i ett finger 24 timmar senare 78 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Resultat Icke-behandlad kontrolltextil (100 % bomull T-shirt) Permetrinbehandlade textilier 100% bomull 100% syntetiska Blandningar T-shirt Långärmad skjorta Långärmad tröja Polyesterlångärmad skjorta Nylonlångärmad skjorta 60% bomull/ 40% polyester långärmad skjorta 50% bomull/ 50% polyester T-shirt 85% svalwick/ 15% lylcra socke 76% bomull/ 21% nylon/ 3% lykra socke 49% polyester/ 47% bomull/ 3% gummi/ 1% spandexsock 1-min exponering Totalt nr. 50 50 50 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 0 0 0 0 0 0 0 0 0 0 % fästingar med normal rörelse 24 timmar senare 96 20 0 8 36 0 0 14 0 0 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 60 16 0 4 24 0 0 0 14 0 0 2 min exponering Totalt nr. av fästingar exponerade 50 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 0 0 0 0 0 0 0 0 0 0 % fästingar med normal rörelse 24 timmar senare 98 0 0 0 0 0 0 0 0 0 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 78 0 0 0 0 0 0 0 0 0 0 0 Visa Stor tabell 4. Resultat Icke-behandlad kontroll textil (100% bomull T-shirt) Permetrin-behandlade textilier 100% bomull 100% syntetiska Blandningar T-shirt Långärmad skjorta Polyester långärmad skjorta Nylon långärmad skjorta 60% bomull/ 40% polyester långärmad skjorta 50% bomull/ 50% polyester T-shirt 85% coolwick/ 15% lycrasocka 76% bomull/ 21% nylon/ 3% lycrasocka 49% polyester/ 47% bomull/ 3% gummi/ 1% spandexsocka 1-min exponering Totalt nr. 50 50 50 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 0 0 0 0 0 0 0 0 0 0 % fästingar med normal rörelse 24 timmar senare 96 20 0 8 36 0 0 14 0 0 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 60 16 0 4 24 0 0 0 14 0 0 2 min exponering Totalt nr. av fästingar exponerade 50 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 0 0 0 0 0 0 0 0 0 0 0 % fästingar med normal rörelse 24 timmar senare 98 0 0 0 0 0 0 0 0 0 0 % fästingar både med normal rörelse och villiga att klättra upp i ett finger 24 timmar senare 78 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Resultat Icke-behandlad kontrolltextil (100 % bomull T-shirt) Permetrinbehandlade textilier 100% bomull 100% syntetiska Blandningar T-shirt Långärmad skjorta Långärmad tröja Polyesterlångärmad skjorta Nylonlångärmad skjorta 60% bomull/ 40% polyester långärmad skjorta 50% bomull/ 50% polyester T-shirt 85% svalwick/ 15% lylcra socke 76% bomull/ 21% nylon/ 3% lykra socke 49% polyester/ 47% bomull/ 3% gummi/ 1% spandexsock 1-min exponering Totalt nr. 50 50 50 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 0 0 0 0 0 0 0 0 0 0 % fästingar med normal rörelse 24 timmar senare 96 20 0 8 36 0 0 14 0 0 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 60 16 0 4 24 0 0 0 14 0 0 2 min exponering Totalt nr. av fästingar exponerade 50 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 0 0 0 0 0 0 0 0 0 0 % fästingar med normal rörelse 24 timmar senare 98 0 0 0 0 0 0 0 0 0 % fästingar både med normal rörelse och villiga att klättra upp i ett finger 24 timmar senare 78 0 0 0 0 0 0 0 0 0 0 0 0 0 Visa stor kontakt Irritans av en enda typ av Permetrinbearbetad beklädnad för laboratorieuppfostrade Nymfer I. scapularis och A. americanum Fästingar Procentandelen fästingar som återstod på analyskortet efter 1 min var signifikant (P < 0,0001) lägre för den permetrinbehandlade textilen jämfört med den icke behandlade kontrolltextilen, både för I. scapularis nymfer (44,0 respektive 98,0 %) och A. americanum nymfer (6,0 respektive 48,0 %). Den irriterande effekten av den behandlade textilen var ännu mer uttalad för I. scapularis-nymfer efter hela 5-min observationsperioden, och endast 2,0 % av fästingarna kvar på den behandlade textilen men 94,0 % kvar på den icke behandlade kontrolltextilen (P < 0,0001). Observationsperioder över 1 min var kontraproduktiva för de mycket rörliga A. americanum-nymferna då >80% av fästingarna hade lossnat från den icke behandlade kontrolltextilen redan med 2 min. Mest troligt på grund av snabb urladdning av A. americanum nymfer från den behandlade textilen, andelen fästingar som visar normal rörelse 24 timmar efter kontakt var liknande för dem som exponeras för icke behandlade och behandlade kläder. Däremot minskade både normal rörelse av I. scapularis-nymfer och normal rörelse i kombination med vilja att klättra ett finger 24 timmar efter exponering signifikant för fästingar som exponerats för permetrin-behandlade kläder jämfört med icke-behandlade kläder (P < 0,0001) (tabell 5). Tabell 5. Utfall A. americanum nymfer I. scapularis nymfer NTCa PTCb NTCa PTCb Totalt nr. För fästingar på testkort 50 50 50 50 % fästingar kvar på testkort efter 1 min 48 6 98 44 % fästingar kvar på testkort efter 2 min 16 0 98 22 % fästingar kvar på testkort efter 3 min 8 0 98 2 % fästingar kvar på testkort efter 4 min 6 0 94 2 % fästingar kvar på testkort efter 5 min 6 0 94 2 % fästingar med normal rörelse 24 timmar senare 100 94 98 2 % fästingar både med normal rörelse och villig att klättra på ett finger 24 timmar senare 96 94 74 0 Resultat A. americanum nymfs I. scapularis nymfs NTCa PTCb NTCa PTCb Totalt nr. Av fästingar som förts in på testkort 50 50 50 % fästingar kvar på testkort efter 1 min 48 6 98 44 % fästingar kvar på testkort efter 2 min 16 0 98 22 % fästingar kvar på testkort efter 3 min 8 0 98 2 % fästingar kvar på testkort efter 4 min 6 0 94 2 % fästingar kvar på testkort efter 5 min 6 0 94 2 % fästingar med normal rörelse 24 timmar senare 100 94 98 2 % fästingar både med normal rörelse och villig att klättra på ett finger 24 timmar senare 96 94 74 0 Se Large Table 5. Utfall A. americanum nymfer I. scapularis nymfer NTCa PTCb NTCa PTCb Totalt nr. För fästingar på testkort 50 50 50 50 % fästingar kvar på testkort efter 1 min 48 6 98 44 % fästingar kvar på testkort efter 2 min 16 0 98 22 % fästingar kvar på testkort efter 3 min 8 0 98 2 % fästingar kvar på testkort efter 4 min 6 0 94 2 % fästingar kvar på testkort efter 5 min 6 0 94 2 % fästingar med normal rörelse 24 timmar senare 100 94 98 2 % fästingar både med normal rörelse och villig att klättra på ett finger 24 timmar senare 96 94 74 0 Resultat A. americanum nymfs I. scapularis nymfs NTCa PTCb NTCa PTCb Totalt nr. av fästingar som införts på analyskort 50 50 50 % fästingar kvar på analyskort efter 1 min 48 6 98 44 % fästingar kvar på analyskort efter 2 min 16 0 98 22 % fästingar kvar på analyskort efter 3 min 8 0 98 2 % fästingar kvar på analyskort efter 4 min 6 0 94 2 % fästingar kvar på analyskort efter 5 min 6 0 94 2 % fästingar med normal rörelse 24 timmar senare 100 94 98 2 % fästingar både med normal rörelse och villig att klättra på ett finger 24 timmar senare 96 94 74 0 Visa Stor toxicitet hos en enda typ av permetrinbehandlad beklädnad för olika fästingar och livsstadier Kontinuerlig exponering för behandlad textil visade en allmän trend av minskande känslighet (dvs. ökad sannolikhet att behålla förmågan att röra sig normalt 1 h efter exponering) från I. scapularis nymfer (0 % med normal rörelse efter en 1-min exponering) till A. americanum nymfer (14,0 %), I. scapularis honor (38,0 %), D. variabilis honor (82,0 %) och A. Förlust av normal rörelse för alla fästingar 1 timme efter kontakt med den behandlade textilen krävde exponeringar på 1 min för I. scapularis nymfer, 2 min för A. americanum nymfer, och 5 min för kvinnliga I. scapularis, D. variabilis, och A. americanum fästingar. Återhämtning av normal rörelse från 1 till 24 timmar efter kontakt med permetrinbehandlade kläder registrerades för vissa (8,0 %) I. scapularis-nymfer som exponerats för 1 min men inte för längre (2 eller 5 min) exponering. För A. americanum-nymfer återfanns 50,0–60,0 % av fästingarna normal rörelse från 1 till 24 timmar efter kontakt som varade i 1–2 minuter, jämfört med endast 10,0 % efter en 5-minusexponering. Mönster för honor var mindre tydliga tvärs över de kortare kontakttiderna men för alla tre arterna noterade vi återhämtning av honor för 5-min kontakt från 1 timme efter exponering (0 % som kan normal rörelse för alla arter) till 24 timmar efter exponering (14,0–24,0 % som kan normal rörelse). En annan intressant iakttagelse var att, i motsats till I. scapularis och A. americanum honor, kortare (1–2 min) exponering för D. variabilis honor verkade resultera i en långsam förgiftningseffekt som resulterade i successiv förlust av normal rörelse över tid: till exempel efter en 1-min exponering normal rörelse hos honorna föll från 82% 1 timme senare till 58% med 24 timmar (tabell 6). Tabell 6. Utfall av Nymphs Females I. scapularis A. americanum I. scapularis A. americanum D. variabilis NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb 1-min exponering Totalt nr. av fästingar exponerade 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 100 14 100 38 98 98 94 82 % fästingar med normal rörelse 24 timmar senare 96 8 100 74 100 44 98 96 94 58 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 60 4 98 72 94 44 46 20 50 12 2-min exponering Totalt nr. 50 50 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 98 0 100 14 100 30 96 42 % fästingar med normal rörelse 24 timmar senare 98 0 98 52 100 22 100 48 96 20 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 78 0 98 52 90 22 40 56 10 5 min exponering Totalt nr. av fästingar utsatta 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 96 0 100 0 100 0 96 0 % fästingar med normal rörelse 24 timmar senare 96 0 100 10 96 20 100 24 96 14 % fästingar både med normal rörelse och villig att klättra upp på ett finger 24 timmar senare 68 0 100 10 92 20 44 22 60 12 Assay outcome Nymphs Honor I. scapularis A. americanum I. scapularis A. americanum D. variabilis NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb 1-min exponering Totalt nr. av fästingar exponerade 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 100 14 100 38 98 98 94 82 % fästingar med normal rörelse 24 timmar senare 96 8 100 74 100 44 98 96 94 58 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 60 4 98 72 94 44 46 20 50 12 2-min exponering Totalt nr. 50 50 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 98 0 100 14 100 30 96 42 % fästingar med normal rörelse 24 timmar senare 98 0 98 52 100 22 100 48 96 20 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 78 0 98 52 90 22 40 56 10 5 min exponering Totalt nr. av fästingar utsatta 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 96 0 100 0 100 0 96 0 % fästingar med normal rörelse 24 timmar senare 96 0 100 10 96 20 100 24 96 14 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 68 0 100 10 92 20 44 22 60 12 Visa stort bord 6. Utfall av Nymphs Females I. scapularis A. americanum I. scapularis A. americanum D. variabilis NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb 1-min exponering Totalt nr. av fästingar exponerade 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 100 14 100 38 98 98 94 82 % fästingar med normal rörelse 24 timmar senare 96 8 100 74 100 44 98 96 94 58 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 60 4 98 72 94 44 46 20 50 12 2-min exponering Totalt nr. 50 50 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 98 0 100 14 100 30 96 42 % fästingar med normal rörelse 24 timmar senare 98 0 98 52 100 22 100 48 96 20 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 78 0 98 52 90 22 40 56 10 5 min exponering Totalt nr. av fästingar utsatta 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 96 0 100 0 100 0 96 0 % fästingar med normal rörelse 24 timmar senare 96 0 100 10 96 20 100 24 96 14 % fästingar både med normal rörelse och villig att klättra upp på ett finger 24 timmar senare 68 0 100 10 92 20 44 22 60 12 Assay outcome Nymphs Honor I. scapularis A. americanum I. scapularis A. americanum D. variabilis NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb 1-min exponering Totalt nr. av fästingar exponerade 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 100 14 100 38 98 98 94 82 % fästingar med normal rörelse 24 timmar senare 96 8 100 74 100 44 98 96 94 58 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 60 4 98 72 94 44 46 20 50 12 2-min exponering Totalt nr. 50 50 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 100 0 98 0 100 14 100 30 96 42 % fästingar med normal rörelse 24 timmar senare 98 0 98 52 100 22 100 48 96 20 % fästingar både med normal rörelse och villiga att klättra ett finger 24 timmar senare 78 0 98 52 90 22 40 56 10 5 min exponering Totalt nr. av fästingar exponerade 50 50 50 50 50 50 50 50 50 50 % fästingar med normal rörelse 1 timme senare 96 0 100 0 100 0 96 0 % fästingar med normal rörelse 24 timmar senare 96 0 100 10 96 20 100 24 96 14 % fästingar både med normal rörelse och villiga att klättra upp på ett finger 24 timmar senare 68 0 100 10 92 20 44 22 60 12 Visa Stora diskussioner Våra bioassayfynd tyder på att permetrinbehandlade kläder har ett löfte som en personlig skyddsåtgärd för att förhindra bett av medicinskt viktiga fästingar i USA. Detta stämmer överens med resultaten från tidigare studier där användning av permetrinbehandlade kläder minskade risken för bett av I. scapularis, A. americanum, och D. variabilis under fältförhållanden eller simulerade fältförhållanden (Schreck et al. 1980, 1982, 1986; Mount and Snoddy 1983; Evans et al. 1990; Miller m.fl. 2011; Vaughn and Meshnick 2011; Vaughn et al. 2014). Av särskild vikt i vår studie är den mycket starka inverkan av permetrin-behandlade kläder på nymfal I. scapularis fästingar, som anses vara de primära vektorerna i USA av sju mänskliga patogener inklusive de orsakande medlen för borrelia, anaplasmos och babesios (Eisen et al. 2017b, Eisen och Eisen 2018). Detta resultat överensstämmer med tidigare studier som visar mycket höga nivåer av skydd mot I. scapularis-nymfer från användning av permetrinbehandlade militära uniformer (Schreck et al. 1986, Evans m.fl. 1990) eller permetrinbehandlade sommarviktskläder (Miller et al. 2011). Vår sida vid sida jämförelse av laboratorieuppfostrade och fältsamlade I. scapularis nymfer föranleddes av en tidigare studie där fältsamlade nymfer som användes i bioassayer flera veckor efter samlingen verkade uppleva kontaktirritans i mindre utsträckning än laboratorieuppfostrade nymfer (Eisen et al. 2017a). I denna studie uppvisade fältnymfer som undersöktes på insamlingsdagen liknande stark kontaktirritans när de introducerades på permetrinbehandlade textilier som laboratorieuppfostrade nymfer (tabell 1). En möjlig förklaring till de motsägelsefulla resultaten för fältsamlade I. scapularis-nymfer i samma kontaktirriterande bioassay i de två studierna kan vara att en fästings förmåga att engagera sig i beteende för att undkomma kontakt med det irriterande substratet är relaterad till dess fysiologiska status. I denna studie användes fältnymferna i bioassay samma dag som de samlades in och utgjorde, vilket framgår av deras höga aktivitet även på den icke behandlade kontrolltextilen (tabell 1), kraftfulla exemplar. I den föregående studien där fältsamlade nymfer inte visade kontaktirriterande beteende när de introducerades på permetrinbehandlade textila (Eisen et al. 2017a) hölls nymferna i laboratoriet i flera veckor innan de användes och visade också en mycket låg aktivitetsnivå på icke behandlad kontrolltextil. Vi spekulerar i att nymfeniga fästingar i dåligt fysiologiskt tillstånd kan övervinnas av de toxiska effekterna av permetrin mycket snabbt, vilket gör dem oförmögna att delta i undvikande beteende som kräver kraftig, samordnad rörelse. Genom våra bioassayförsök förlorade både laboratorieuppfostrade och fältsamlade I. scapularis-nymfer genomgående kapacitet för normal rörelse, och innebar därmed inte mer än minimal risk för bitning med 1 timme efter påtvingad kontakt med permetrinbehandlade kläder under 1 min (tabellerna 2, 4 och 6). Som också rapporterats i vår tidigare studie (Eisen m.fl. 2017a), vissa fästingar återhämtade kapacitet för normal förflyttning med 24 timmar efter exponering eftersom effekten av permetrinförgiftning avtog. Alla undersökta typer av permetrinbehandlade kläder var mycket giftiga för I. scapularis-nymfer, oavsett om textilen var 100% bomull, 100% syntetiskt material eller blandningar (tabell 4). Ett intressant resultat är att även om alla tre typer av strumpor som undersöktes var mycket giftiga för nymferna (0 % fästingar med normal rörelse 1 timme efter påtvingad 1-minusexponering i alla tre fallen), kvarstod en mycket högre andel fästingar efter 5 minuter i den vertikala kontaktretlighetsanalysen på en av de undersökta strumporna (94 %) jämfört med de andra två strumporna (22-26 %). I stället för bristande kontaktretlighet spekulerar vi i att detta kan ha berott på en lösare väv och mer ”fuzzy” yta på strumpan på vilken fästingar var mindre benägna att lossna, vilket kanske ledde till att de oftare fastnade i fibrerna och inte lyckades fly den irriterande textilen. En tidigare fältstudie visade att A. americanum-nymfer lätt kan hålla sig fästa vid vertikalt orienterade strumpor medan försökspersonerna går (Bissinger et al. 2011). Kanske inte överraskande visade vår jämförelse sida vid sida mellan olika fästingar och livsstadier att allteftersom fästingar ökade i storlek – från I. scapularis nymfer till A. americanum nymfer och I. scapularis, A. americanum och D. variabilis honor – krävdes en längre tids kontakt med permetrinbehandlad textil för att uppnå förlust av normal rörelse. 5 min kontakt var dock tillräcklig för att fästingar av alla arter skulle kunna förlora sin förmåga att röra sig normalt 1 timme efter exponering. Mycket återstår att utforska när det gäller permetrinbehandlade textiliers inverkan på olika fästingars arter och livsstadier, både när det gäller deras medfödda känslighet för permetrin och deras hållning, vilket kan påverka deras kontaktnivå med den behandlade textilen. Det står till exempel att den ventrala sidan av kroppen och kapitälet hos en mindre fästing med kortare ben oftare skulle få kontakt med den behandlade textilen jämfört med en större fästing med längre ben. Dessutom kan det specifika flyktbeteendet vid kontakt med en vertikalbehandlad textil, till exempel ett strumpben eller byxben, också vara viktigt: det typiska svaret från I. scapularis nymfer är att aktivt vända och tumla nedåt (Eisen 2017a) vilket leder till att både deras ventrala och dorsala ytor kommer i kontakt med den behandlade textilen. Vår studie hade betydande begränsningar, viktigast av allt att vi bara undersökte orörda permetrin-behandlade kläder och därför har inga data för hur bära och tvätta plaggen kan påverka deras kontakt irritation och toxicitet mot fästingar. Med undantag för några av I. scapularis-nymferna, de fästingar som används i bioassayerna föddes upp i laboratoriet och det skulle därför vara fördelaktigt att bekräfta resultaten med fältsamlade exemplar från olika delar av de geografiska utbredningsområdena för medicinskt viktiga fästingar. Dessutom kommer bedömning av kontaktirritans hos permetrinbehandlade textilier för mycket rörliga fästingar hos honor att kräva modifiering av vår befintliga bioassay då honorna snabbt gick bort från små analyskort med icke behandlad kontrolltextil. Andra begränsningar av bioassayerna och fästingvigor bedömning diskuterades tidigare (Eisen et al. 2017a). Viktiga återstående frågor om möjligheten för permetrinbehandlade kläder att skydda mot bett av vektorfästingar och i slutändan minska fästingars fästingars fästingburna sjukdom är följande: 1) potentiell effektivitetsförlust efter upprepad slitage och tvättning, vilket observerats för myggvektorer (DeRaedt Banks et al. 2015, Faulde et al. 2016, Orsborne et al. 2016, Kittayapong et al. 2017, Richards et al. 2017); 2) graden av acceptans för användning av permetrinbehandlade kläder (Richards et al. 2014); och 3) individers villighet att ändra sitt beteende genom att konsekvent ta på sig permetrinbehandlade kläder när man går in i fästinghabitat (Vaughn et al. 2014), särskilt om detta inkluderar delar av din egen bakgård och kräver daglig handling. Vi måste också bättre förstå vilka delar av kroppen som måste täckas av permetrinbehandlade kläder för att uppnå ett starkt skydd mot fästingar med olika värdsökande strategier. Enbart behandlade skor eller strumpor kan till exempel vara någorlunda effektiva mot rörliga ”jägare” fästingar som kan få kontakt med människor genom att aktivt söka upp deras nedre extremiteter när de står stilla. Mer omfattande täckning av permetrinbehandlade plagg kan dock krävas för att skydda mot fästingar som snarare använder en bakhållsstrategi och i huvudsak väntar på att värdar kontaktar dem, såsom nymfer av I. scapularis och de närbesläktade Ixodes pacificcus Cooley och Kohls (Acari: Ixodidae). Människor ökar kraftigt risken för kontakt med nymfer av dessa arter när de plockar upp saker från marken (ticks kommer på händer och armar) eller knäböjer eller sitter på marken eller naturliga drag som stockar (ticks komma på benen) snarare än att bara gå genom miljön (Carroll och Kramer 2001, Lane et al. 2004). Följaktligen kan tillräckligt skydd mot bett från nymfal I. scapularis fästingar kräva att man inte bara bär permetrinbehandlade skor/sockor utan även permetrinbehandlade fullängdsbyxor och långärmade skjortor. Tack Vi tackar Adam Thompson (Camp Ripley Training Center) för hjälp med fältlogistik. Resultaten och slutsatserna av denna studie är av författarna och representerar inte nödvändigtvis åsikterna från Centers for Disease Control and Prevention. Referenser Cited Bissinger , B. W. C. S. Apperson D. W. Watson C. Arellano D. E. Sonenshine R. M. Roe , och 2011 . Nya fältanalyser och den komparativa repellensen av BioUD(®), DEET och permetrin mot Amblyomma americanum . Med. Vet. Entomol. 25 : 217 – 226 . Carroll, J. F. M. Kramer, och 2001 . Olika aktiviteter och skodon påverkar exponeringen för värdsökande nymfer av Ixodes scapularis och Amblyomma americanum (Acari: Ixodidae) . J. Med. Entomol. 38 : 596 – 600 . DeRaedt Banks, S. J. Orsborne S. A. Gezan H. Kaur A. Wilder-Smith S. W. Lindsey J. G. Logan , och 2015 . Permetrin-behandlade kläder som skydd mot dengue vektor, Aedes aegypti: omfattning och varaktighet av skydd. Plos Negl. Trop. Dis. 9 : e0004109 . Eisen, R. J. L. Eisen, och 2018 . Den svartbenta fästingen, Ixodes scapularis: ett ökande folkhälsoproblem. Trender Parasitol . 34 : 295–309. : 295–309. Eisen , L. D. Rose R. Prose N. E. Breuner M. C. Dolan K. Thompson N. Connally , och 2017a . Bioassays för att utvärdera icke-kontakt rumslig repellens, kontaktirritans, och akut toxicitet av permetrin-behandlade kläder mot nymphal Ixodes scapularis fästingar. Ticks. Borne. Dis. 8 : 837 – 849 . Eisen , R. J. K. J. Kugeler L. Eisen C. B. Skägg C. D. Paddock , och 2017b . Tickburna zoonoser i USA: ihållande och framväxande hot mot människors hälsa. ILAR J. 58 : 319–335. : 319–335. Evans, S. R. G. W. Korch, Jr., Jr M. A. Lawson, och 1990 . Jämförande fältutvärdering av permetrin och deetbehandlade militära uniformer för personligt skydd mot fästingar (Acari) . J. Med. Entomol. 27 : 829 – 834 . Faulde, M. W. Uedelhoven, och 2006 . En ny klädimpregneringsmetod för personligt skydd mot fästingar och bitande insekter. Int. J. Med. Mikrobiol. 296 ( Suppl 40 ): 225 – 229 . ): Faulde, M. K. F. Sidor W. Uedelhoven, och 2016 . Bioaktivitet och tvättmotstånd av fem kommersiellt tillgängliga, fabriksbehandlade permetrinimpregnerade tyger för att förebygga myggburna sjukdomar: behovet av ett standardiserat test- och tillståndsförfarande. Parasitol. Res. 115 : 1573 – 1582 . Jordanien, R. A. T. L. Schulze M. C. Dolan , och 2012 . Effekten av växtbaserade och syntetiska föreningar på kläder som repellenter mot Ixodes scapularis och Amblyomma americanum (Acari: Ixodidae) . J. Med. Entomol. 49 : 101 – 106 . Kittayapong, P. P. Olanratmanee P. Maskhao P. Byass J. Logan Y. Tozan V. Louis D. J. Gubler A. Wilder-Smith , och 2017 . Förmildrande sjukdomar som överförs av Aedesmyggor: en klusilrandomiserad prövning av permetrinimpregnerade skoluniformer. Plos Negl. Trop. Dis. 11 : e0005197 . Lane, R. S. D. B. Steinlein J. Mun , och 2004 . Mänskliga beteenden höja exponeringen för Ixodes pacificus (Acari: Ixodidae) nymfer och deras tillhörande bakteriella zoonotiska medel i en lövskog. J. Med. Entomol. 41 : 239 – 248 . Miller , N. J. E. E. Rainone M. C. Dyer M. L. González T. N. Mather , och 2011 . Fästingbettskydd med permetrinbehandlade sommarviktskläder. J. Med. Entomol. 48 : 327 – 333 . Mount, G. A. E. L. Snoddy, och 1983. Trycksatt spray av permetrin och detet på kläder för personligt skydd mot den ensamme stjärnticken och den amerikanska hundticken (Acari: Ixodidae) . J. Econ. Entomol. 76 : 529 – 531 . Orsborne, J. S. DeRaedt Banks A. Hendy S. A. Gezan H. Kaur A. Wilder-Smith S. W. Lindsay J. G. Logan , och 2016 . Personligt skydd av permetrinbehandlade kläder mot Aedes aegypti, vektorn för dengue- och zikavirus, i laboratoriet. Plos One 11 : e0152805 . Richards, S. L. J. A. G. Balanay J. W. Harris , och 2014 . Effektivitet av permetrin-behandlade kläder för att förhindra fästingar exponering hos skogsarbetare i den centrala Appalachiska regionen i USA . Int. J. Environ Hälsa Res. 25 : 453 – 462 . Richards, S. L. J. A. G. Balanay J. W. Harris V. M. Banks S. Meshnick , och 2017 . Rester av effektivitet permetrin-behandlade kläder för att förhindra myggbett under simulerade förhållanden. J. Environ Hälsa. 79 : 8 – 15 . Schreck, C. E. K. Posey D. Smith , och 1978 . Hållbarhet av permetrin som en potentiell klädbehandling för att skydda mot blodätande leddjur. J. Econ. Entomol. 71 : 397 – 400 . Schreck, C. E. E. L. Snoddy G. A. Mount , och 1980 . Permetrin och avvisande medel som klädimpregneringsmedel för skydd mot den ensamma stjärnan fästing. J. Econ. Entomol. 73 : 436 – 439 . Schreck, C. E. G. A. Mount D. A. Carlson , och 1982 . Trycksatt spray av permetrin på kläder för personligt skydd mot den ensamma stjärnfästingen (Acari: Ixodidae) . J. Econ. Entomol. 75 : 1059 – 1061 . Schreck, C. E. E. L. Snoddy A. Spielman, och 1986 . Tryckspruta av permetrin eller detet på militärkläder för personligt skydd mot Ixodes dammini (Acari: Ixodidae) . J. Med. Entomol. 23 : 396 – 399 . Vaughn, M. F. S. R. Meshnick, och 2011 . Pilotstudie som utvärderar effektiviteten av långvariga permetrinimpregnerade kläder för att förebygga fästingbett. Vector Borne Zoonotic Dis . 11 : 869 – 875 . Vaughn , M. F. S. W. Funkhouser F. C. Lin J. Fine J. J. Juliano C. S. Apperson S. R. Meshnick , och 2014 . Långvariga permetrinimpregnerade uniformer: en randomiserad kontrollerad studie för att förebygga fästingbett. Am. J. Föregående Med. 46 : 473 – 480 . Utgiven av Oxford University Press på uppdrag av Entomological Society of America 2018. Forskare vid centrum för sjukdomsbekämpning och -förebyggande (CDC) tror att de kan bekämpa de fästingburna sjukdomarnas gissel genom att uppmuntra människor att hälla sina kläder i ett kemiskt ämne som kallas permetrin. I en ny studie, publicerad idag (24 maj) i Journal of Medical Entomology, visade forskare att permetrinbehandlade kläder allvarligt kan förstöra en fästings steg. Stick några vuxna fästingar på ett par vanliga byxor lutade i 45-graders vinkel, och 100 procent av dem kommer fortfarande att klamra sig fast på 5 minuter senare. Stick vuxna fästingar på ett par lutade byxor som behandlas med permetrin, men, och 42,5 procent kommer att tumla av helt. Även de som finns kvar blir allvarligt förstörda. Forskarna fann att bara 25 procent av fästingarna rörde sig normalt även 24 timmar efter exponering. "Alla testade fästingarter och livsstadier upplevde irritation, den 'varma foten' effekten, efter att ha kommit i kontakt med permetrinbehandlade kläder", sade Lars Eisen, en CDC-entomolog som arbetade med studien, i ett uttalande. Permetrin är ingen ny kemikalie. Du kan redan köpa kläder belagda i sakerna, som en tillverkare marknadsför som repelling "moskvitéer, fästingar, myror, flugor, chiggers och dvärgar" och framhärdar på kläderna genom minst 70 ronder i tvättmaskinen. Drugs.com rekommenderar det som en behandling för löss och skabb, och uppger att det inte är känt för att vara giftigt för människor – även om det kan orsaka en del lindrig irritation hos vissa människor. Forskare sa i tidningen att det fortfarande inte är känt hur länge permetrin är effektivt i kläder, eftersom alla kläder de testade var "pristinska" och nybehandlade. Men dessa resultat tyder på verkliga fördelar för permetrin-behandlade strumpor, byxor och andra kläder, sade de. Fästingar är ansvariga för ett antal allvarliga sjukdomar, som Live Science tidigare har rapporterat, inklusive borrelia. Och deras utbredningsområde verkar sprida sig, sannolikt på grund av klimatförändringarna. Det betyder att för forskare vid CDC är det allt viktigare att stoppa dem. Ursprungligen publicerad på Live Science. Skriv en sammanfattning.
Abstract Clothing treated with pyrethroid permethrin is available in the United States as consumer products to prevent tick bites. We used tick bioassays to quantify contact irritance and toxicity of permethrin-treated clothing for three important tick vectors of human pathogens: the black-legged tick, Ixodes scapularis Say (Acari: Ixodidae); the lone star tick, Amblyomma americanum (L.) (Acari: Ixodidae); and the American dog tick, Dermacentor variabilis (Say) (Acari: Ixodidae). We first showed that field collected I. scapularis nymphs from Minnesota were as susceptible as laboratory-bred nymphs for a permethrin-treated textile. Field ticks examined in bioassays on the day they were collected were shown contact irritancy by actively disengaging from a vertically oriented permethrin-treated textile, and a forced exposure of 1 min resulted in all ticks being unable to move normally, which involved no more than minimal risk of biting, 1 hour after contact with the treated textile. In addition, we have documented a lack of normal movement for laboratory-bred I. scapularis nymphs with 1 hour after contact for 1 min with a wide range of permethrin-treated clothing, including garments made of cotton, synthetic materials, and mixtures. A comparison of the impact of a permethrin-treated textile over ticks and life stages showed the strongest effect on I. scapulari nymphs (0% with normal movement 1 hour after a 1-min exposure), followed by A. americanum nymphs (14.0%), I. scapulari's females (38.0%), D. variabili's females (82.0%) and A. americanum females (98.0%). Loss of normal movement for all ticks 1 hour after contact with the permethrin-treated textile required exposures of 1 min for I. scapularis nymphs, 2 min for A. americanum nymphs, and 5 min for female I. scapularis, D. variabilis, and A. americanum ticks. We conclude that the use of permethrin-treated clothing shows promise to prevent bites of medically important ticks. Further research needs are being discussed. Many studies over the past four decades have shown that permethrin-treated clothing is effective against tick vectors of human pathogens in the United States, including the black-legged tick, Ixodes scapularis Say (Acari: Ixodidae); the lone star tick, Amblyomma americanum (L.) (Acari: Ixodidae); and the American dog fort, Dermacentor variabilis (Say) (Acari: Ixodidae) (Schreck et al. 1978, 1980, 1982, 1986; Mount and Snoddy 1983; Evans et al. 1990; Miller et al. 2011; Vaughn and Meshnick 2011; Jordan et al. 2012; Vaughn et al. 2014, Eisen et al. 2017a). In addition to the use of permethrin in pressurised sprays to self-treat clothing, refined method for textile impregnation (Faulle and Uedelhoven 2006, Faulde et al. 2016) has led to new tick-resistant consumer products in the form of permethrin-treated clothing. Insect Shield, LLC (Greensboro, NC) is a leading manufacturer of permethrin-treated clothing in the United States. In a previous study (Eisen et al. In 2017a), we used material from a permethrin-treated T-shirt (100% cotton) from Insect Shield to develop a set of new bioassays to quantify contact irritancy and toxicity of permethrin-treated clothing against nymphal I. scapularis ticks, the primary vectors in eastern North America of the causative agents of Lyme disease, anaplasmosis, and babesiosis (Eisen et al. 2017b). In addition to demonstrating contact irritancy and toxicity of the tested permethrin-treated cotton textile for I. scapularis nymphs, we observed what appeared to be a weaker contact irritant ‘hotfoot’ effect for field-collected versus laboratory-bred nymphs (Eisen et al. 2017a). However, in that study, the field-collected nymphs in the laboratory were kept below ≥2 wk before being used, which may have affected their performance in contact-relationship bioassay relative to the normal scenario of naturally seeking nymphs encountering permethrin-treated clothing on a human in the field. Here we report on a set of studies using the new bioassays as follows: (1) comparing contact rigor and toxicity of a single type of permethrin-treated clothing for laboratory-bred versus field collected I. scapularis nymphs; (2) comparing contact elasticity and toxicity of permethrin-treated clothing made from different types of textiles for I. scapularis nymphs; and (3) comparing the toxicity of a single type of permethrin-treated clothing for the primary human-biting stages of I. scapularis (nymphs and females), A. americanum (nymphs and females), and D. variabilis (females). Materials and methods Sources of Permethrin-Processed clothing and ticks Ten different types of permethrin-treated clothing purchased directly from Insect Shield were included in this study. Of these, three were clothing 100% cotton (T-shirt, long-sleeved shirt, and trousers), three were 100% synthetic textiles in the form of shirts (100% polyester shirt and 100% nylon shirt) or socks (85% coolwick/15% lycra spandex compression sock), and four were blends of cotton and synthetic textiles in the form of shirts (60% cotton/40% polyester shirt and 50% cotton/50% polyester shirt) or socks (76% cotton/21% nylon/3% Lykra sock and 49% polyester/47% cotton/3% rubber/1% spandex sock). All clothing was in pristine condition (not washed or worn) when used in the bioassays. The untreated control textile was always a 100% cotton T-shirt. Textile pieces for use in the bioassays were cut from the front or back of the shirts, the lower legs of the trousers and the upper part of socks extending above a shoe. The ticks used in the study were taken from Oklahoma State University (OSU) Tick Rearing Facility (Stillwater, OK). These included I. scapulari's nymphs and females, A. americanum nymphs and females, and D. variablis' females, all of unknown age. Before using the ticks, they were held within glass desiccators (90-95% RH) in a growth chamber held at 21 to 22°C with a 16:8 h light:dark cycle. The only exception was for OSU I. scapularis nymphs used in the field along with field-collected I. scapularis nymphs: these OSU ticks were placed in plastic desiccators equipped with water and held under ambient conditions, in the same complex where the bioassays were performed at Camp Ripley Training Center, Morrison County, MN, for about 1 wk before being used in bioassays. Field-collected I. scapularis nymphs came from locations at Camp Ripley Training Center. These ticks were taken from the vegetation 21–24 June 2017, using white cotton utility cloth as tick features. All nymphs were used in bioassays on the day they were collected, typically within 4 hours of collection. Contact Irritation and toxicity Bioassays Our vertical (45° angle) bioassay to assess contact irritancy was described in detail earlier (Eisen et al. 2017a) and contains a playing card (64-mm wide of 89-mm high) on which a test textile is sewn. Ticks are introduced in the middle of the textile-covered card and the number remaining on the card is scored at 1-minute intervals over a 5-minute period. We found that this bioassay was suitable for nymphal ticks but not for the more mobile adult ticks, as these were very quickly detached even from cards with untreated control textiles. Based on their varied mobility, we found it convenient to observe ticks within groups of 10 I. scapularis nymphs or 5 A. americanum nymphs per bioassay. After exposure, ticks were kept in desiccators (90-95% RH) at room temperature in the laboratory or at ambient temperature in the field setting until they received results for vigor 24 hours later. Bioassays with untreated textile had survival rates of ≥90% at 24 hours post-exposure. Our bioassay to assess toxicity was described in detail earlier (Eisen et al. In the case of a test chemical, the test chemical should be tested in accordance with the test method described in Annex II. In this study we used exposure times 1, 2 and 5 min. Based on their varied mobility, we found it appropriate to use groups of 10 I. scapularis nymphs, 5 A. americanum nymphs, or 5 female ticks of any species per bioassay. Nymphal ticks were exposed using a 10 cm diameter textile circle placed in a Petri bowl, while the more mobile females were exposed on a larger, 18 × 13 cm large piece of textile attached to a plastic tray. After exposure, ticks in desiccators (90-95% RH) were kept at room temperature in the laboratory until they received scores for vigor 1 and 24 hours later. Bioassay with untreated control materials had a survival rate of ≥90% at 24 hours post-exposure. Bioassays to compare the effect of permethrin-treated clothing made from different types of textiles were limited to laboratory-bred I. scapularis nymphs. Bioassays to compare the impact of permethrin-treated clothing on laboratory-bred versus field-collected I. scapularis nymphs, or the primary human-biting life stages of various ticks, were limited to a single type of permethrin-treated clothing (100% cotton). Classification scheme for tick vigor We used the classification scheme after exposure to tick vigor described earlier by Eisen et al. (2017a). In short, tick vigor after introduction to an untreated surface and stimulation of activity via mild physical prodding and human breath were made over four categories of motion: (1) tick completely immobile; (2) tick that can any movement of the legs but cannot straighten or walk; (3) tick that can straighten itself out but cannot move in a coordinated manner or easily orient itself towards a stimulus; and (4) tick that shows normal movement and response to a stimulus. Ticks made to show normal movement (4) were further assessed to determine whether to rise on a finger when given the chance. Data analysis We compared the proportions of ticks that presented different responses to permethrin-treated clothing with those exposed to non-treated controls using Fisher's exact test. The results were considered significant at α = 0.05, with a single-tail test. All comparisons were made in JMP Pro 13 (Cary, NC). Results Contact Irritance and toxicity of a single type of Permethrin-Processed Clothes for Laboratory-Propeated Versus Field-Collected I. scapularis Nymphs In the contact analysis, the proportion of ticks remaining on the analysis card after 1 min was significantly lower (P < 0.0001) for permethrin-treated textiles compared to the non-treated control textiles, both for laboratory-bred nymphs (57.5 and 100% respectively) and field-collected nymphs (32.5 and 85.0%, respectively) (Table 1). At the end of the observation period of 5 minutes, the difference was even more pronounced for the laboratory-bred nymphs, with 100% of the nymphs still on the non-treated control but only 5.0% remaining on the permethrin-treated textile (P < 0.0001). The field-collected nymphs were significantly more active and were less likely to remain on the analysis card with untreated control textiles for a full 5 minutes. Despite this, it was still marginally less likely that they remained on the permethrin-treated textile compared to the untreated control textile at the 5-minute point (7.5 and 22.5% respectively; P = 0.0574). In addition, the proportion of ticks that showed normal movement 24 hours after exposure significantly decreased (P < 0.001) after contact with permethrin-treated textiles compared to the untreated control textiles, both for the laboratory-bred nymphs (25.0 and 100% respectively) and the field-collected nymphs (45.0 and 100% respectively) (Table 1). And even fewer ticks showed both normal movement and were willing to lift the fingertip when one was given the opportunity (Table 1). For the field-collected nymphs, exposure to permethrin-treated textiles resulted in only 17.5% both showing normal movement and climbing up on a finger 24 hours after exposure, compared to 80.0% for exposure to untreated control textiles (P < 0.0001). Table 1. Analysis results nymphs from the laboratory Field collected nymphs NTCa PTCb NTCa PTCb Total No. Of ticks inserted on analysis card 40 40 40 % ticks left on analysis card after 1 min 100 57,5 85,0 32,5 % ticks left on analysis card after 2 min 100 42,5 47,5 22,5 % ticks left on analysis card after 3 min 100 22,5 37,5 12,5 % ticks left on analysis card after 4 min 100 15,0 32,5 % ticks left on analysis card after 5 min 100 5,0 22,5 7,5 % ticks with normal movement 24 hours later 100 25,0 100 45,0 % ticks both with normal movement and willing to climb up on a finger 24 hours later 27,5 7,5 80,0 17,5 Results Laboratory raised nymphs Field-collected nymphs NTCa PTCb NTCa PTCb Total No. of ticks inserted on analysis card 40 40 40 % ticks left on analysis card after 1 min 100 57,5 85,0 32,5 % ticks left on analysis card after 2 min 100 42,5 47,5 22,5 % ticks left on analysis card after 3 min 100 22,5 37,5 12,5 % ticks left on analysis card after 4 min 100 15,0 32,5 12,5 % ticks left on analysis card after 5 min 100 5,0 22,5 7,5 % normal movement ticks 24 hours later 100 25,0 100 45,0 % ticks both with normal movement and willing to climb up on a finger 24 hours later 27,5 7,5 80,0 17,5 View Large table 1. Analysis results nymphs from the laboratory Field collected nymphs NTCa PTCb NTCa PTCb Total No. Of ticks inserted on analysis card 40 40 40 % ticks left on analysis card after 1 min 100 57,5 85,0 32,5 % ticks left on analysis card after 2 min 100 42,5 47,5 22,5 % ticks left on analysis card after 3 min 100 22,5 37,5 12,5 % ticks left on analysis card after 4 min 100 15,0 32,5 % ticks left on analysis card after 5 min 100 5,0 22,5 7,5 % ticks with normal movement 24 hours later 100 25,0 100 45,0 % ticks both with normal movement and willing to climb up on a finger 24 hours later 27,5 7,5 80,0 17,5 Results Laboratory raised nymphs Field-collected nymphs NTCa PTCb NTCa PTCb Total No. If ticks introduced to analysis card 40 40 40 % ticks remain on analysis card after 1 min 100 57,5 85,0 32,5 % ticks remaining on analysis card after 2 min 100 42,5 22,5 % ticks remaining on analysis card after 3 min 100 22,5 37,5 12,5 % ticks remaining on analysis card after 4 min 100 15,0 32,5 % ticks remaining on analysis card after 5 min 100 5,0 22,5 % normal motion ticks 24 hours later 100 25,0 100 45,0 % ticks both with normal motion and willing to climb on a finger 24 hours later 27,5 7,5 80,0 17,5 Show large In the toxicity test test test test result in continuous contact with test textiles for 1 min in significant (P < 0,0001) reductions (≥90 percentage points) for ticks to show normal motion after exposure to permethrin treated textile compared to the untreated controltextile, whether we analysed laboratory-bred or field-collected nymphs and whether ticks were made at 1 or 24 h after . In particular, no field-collected nymphs showed normal movement 1 hour after 1-min exposure to the permethrin-treated textile, and only 5% of the nymphs that had been exposed over such a short period of time had recovered normal movement 24 hours after exposure. For the field-collected nymphs, 1-min exposure to permethrin-treated textiles resulted in only 2.5% both showing normal movement and climbing up on a finger 24 hours after exposure, compared to 52.5% for exposure to untreated control textiles (P < 0.0001). Table 2. Analysis results nymphs from the laboratory Field collected nymphs NTCa PTCb NTCa PTCb Total No. ticks exposed 40 40 40 40 % ticks with normal movement 1 hour later 100 0 100 0 % ticks with normal movement 24 hours later 100 7,5 95,0 5,0 % ticks both with normal movement and willing to climb a finger 24 hours later 37,5 0 52,5 Outcomes from laboratory-bred nymphs Field-collected nymphs NTCa PTCb NTCa PTCb Total No. ticks exposed 40 40 40 40 % ticks with normal movement 1 hour later 100 0 100 0 % ticks with normal movement 24 hours later 100 7,5 95,0 5,0 % ticks both with normal movement and willing to climb a finger 24 hours later 37,5 0 52,5 2,5 Show large table 2. Analysis results nymphs from the laboratory Field collected nymphs NTCa PTCb NTCa PTCb Total No. ticks exposed 40 40 40 40 % ticks with normal movement 1 hour later 100 0 100 0 % ticks with normal movement 24 hours later 100 7,5 95,0 5,0 % ticks both with normal movement and willing to climb a finger 24 hours later 37,5 0 52,5 Outcomes from laboratory-bred nymphs Field-collected nymphs NTCa PTCb NTCa PTCb Total No. ticks exposed 40 40 40 40 % ticks with normal movement 1 hour later 100 0 100 0 % ticks with normal movement 24 hours later 100 7,5 95,0 5,0 % ticks both with normal movement and willing to climb on a finger 24 hours later 37,5 0 52,5 Show large contact irritancy and toxicity of Permethrin-processed clothing made from different types of textiles for Laboratory-Reared I. scapularis Nymfs The main results of the contact-rettan analysis were that exposure to permethrin-treated textiles, compared to non-treated control textiles, resulted in significant reductions (P < 0.0001) in the proportion of ticks left on the analysis card after 5 minutes for 9 of 10 different types of treated clothing, and in percentage of ticks showing normal movement 24 hours after exposure to all 10 different types of treated clothing (Table 3). In particular, the proportion of ticks that showed normal movement 24 hours after exposure was reduced to ≤ 20,0 % for all tested types of treated clothing and to < 5,0 % for 6 of 10 types of treated clothing. We also note that one of the sock textiles examined – a 49% polyester/47% cotton/3% rubber/1% spandex sock – had a unique combined effect with nymphs not being able to disengage from it but being seriously affected and uniform could not move normally 24 hours after exposure. Table 3. Results Non-treated control textile (100% cotton T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Mixtures T-shirt Long-sleeved shirt Polyester long-sleeved shirt Nylon long-sleeved shirt 60% cotton/ 40% polyester long-sleeved shirt 50% cotton/ 50% polyester T-shirt 85% coolwick/ 15% lycrasocka 76% cotton/ 21% nylon/ 3% lycrasocka 49% polyester/ 47% cotton/ 3% rubber/ 1% spandex sock Total No. T-shirt Long-sleeved shirt Long-sleeved shirt Long-sleeved cotton/ cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % ticks left on analysis card after 1 min 98 92 56 56 94 46 66 90 98 100 % ticks left on analysis card after 2 min 98 22 76 18 46 70 86 96 % ticks left on analysis card after 3 min 98 60 18 2 56 4 4 4 14 36 58 96 % ticks left on analysis card after 4 min 94 8 4 4 4 4 0 40 % ticks left on analysis card after 10 min 94 40 % 94 2 2 2 2 30 0 94 % ticks left on analysis card after 5 min 2 2 2 2 2 14 20 0 % fasteners both with normal movement and willing to climb up a finger 24 h later 74 0 4 0 40 % 0 0 Ticks inserted on analysis card 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks left on analysis card after 1 min 98 92 56 44 94 46 54 66 90 98 100 % ticks left on analysis card after 2 min 98 78 22 76 18 22 46 70 86 96 % ticks left on analysis card after 3 min 98 60 18 2 56 4 14 36 40 58 96 % ticks left on analysis card after 4 min 94 44 8 2 40 0 10 28 26 40 94% ticks left on analysis card after 5 min 94 40 2 2 30 0 6 22 26 94% ticks with normal movement 24 hours later 98 0 6 2 14 20 0 14 0 0 0 0 % ticks both with normal movement and willing to climb up on a finger 24 hours later 74 0 2 8 14 0 0 Show Large table 3. Results Non-treated control textile (100% cotton T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Mixtures T-shirt Long-sleeved shirt Polyester long-sleeved shirt Nylon long-sleeved shirt 60% cotton/ 40% polyester long-sleeved shirt 50% cotton/ 50% polyester T-shirt 85% coolwick/ 15% lycrasocka 76% cotton/ 21% nylon/ 3% lycrasocka 49% polyester/ 47% cotton/ 3% rubber/ 1% spandex sock Total No. T-shirt Long-sleeved shirt Long-sleeved shirt Long-sleeved cotton/ cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % cotton/ 5 % ticks left on analysis card after 1 min 98 92 56 56 94 46 66 90 98 100 % ticks left on analysis card after 2 min 98 22 76 18 46 70 86 96 % ticks left on analysis card after 3 min 98 60 18 2 56 4 4 4 14 36 58 96 % ticks left on analysis card after 4 min 94 8 4 4 4 4 0 40 % ticks left on analysis card after 10 min 94 40 % 94 2 2 2 2 30 0 94 % ticks left on analysis card after 5 min 2 2 2 2 2 14 20 0 % fasteners both with normal movement and willing to climb up a finger 24 h later 74 0 4 0 40 % 0 0 Ticks introduced to analysis cards 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks left on analysis cards after 1 min 98 92 56 44 94 46 54 66 90 98 100 % ticks left on analysis cards after 2 min 98 78 22 76 18 46 70 86 96 % ticks left on analysis cards after 3 min 98 60 18 2 56 4 14 36 40 58 96 % ticks left on analysis cards after 4 min 94 8 2 40 0 10 28 26 40 94 % ticks left on analysis cards after 5 min 94 40 2 2 30 0 6 22 26 94 % ticks with normal movement 24 h later 98 0 6 2 14 20 0 14 0 0 0 0 % ticks both with normal movement and willing to climb a finger 24 h later 74 0 2 8 14 0 0 Show large In the toxicity analysis, a 2-min exposure led to lack of normal movement 1 and 24 hours after exposure to all ticks exposed to treated textiles, regardless of type of clothing (Table 4). This corresponded to a significant (P < 0.0001) decrease in normal movement at 1 and 24 hours, respectively, after exposure to all treated textiles compared to non-treated control textiles (100 and 98.0%, respectively, of nymphs with normal movement). When the exposure time was reduced to 1 min, the absence of normal movement of all ticks was still recorded by 1 and 24 hours after exposure to 6 of 10 types of treated textile. Exposure to the other four types of treated textile resulted in a lack of normal movement for all ticks 1 hour after exposure but variable probability (8.0–36.0%) for recovery of normal motion by 24 hours after exposure. These results for 1-min contact time represented a significant (P < 0.0001) decrease in normal movement at 1 and 24 hours after exposure to all treated textiles compared to untreated control textiles. Table 4. Results Non-treated control textile (100% cotton T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Mixtures T-shirt Long-sleeved shirt Polyester long-sleeved shirt Nylon long-sleeved shirt 60% cotton/ 40% polyester long-sleeved shirt 50% cotton/ 50% polyester T-shirt 85% coolwick/ 15% lycrasocka 76% cotton/ 21% nylon/ 3% lycrasocka 49% polyester/ 47% cotton/ 3% rubber/ 1% spandex sock 1-min exposure Total No. 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 0 0 0 0 0 0 0 0 0 % normal motion ticks 24 hours later 96 20 0 8 36 0 0 0 14 0 0 0 % ticks both with normal movement and willing to climb a finger 24 hours later 60 16 0 4 24 0 0 0 0 14 0 0 2 min exposure Total No. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 0 0 0 0 0 0 0 0 0 0 0 0 % ticks with normal movement 24 hours later 98 0 0 0 0 0 0 0 0 0 0 0 0 % ticks both with normal movement and willing to climb into a finger 24 hours later 78 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Results Non-treated control textile (100 % cotton T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Mixing T-shirt Long-sleeved shirt Long-sleeved shirt Polyester-sleeved shirt Nylon-sleeved shirt 60% cotton/ 40% polyester long-sleeved shirt 50% cotton/ 50% polyester T-shirt 85% swallowwick/ 15% lylcra socks 76% cotton/ 21% nylon/ 3% Lycre socks 49% polyester/ 47% cotton/ 3% rubber/ 1% spandex-min exposure Total No. 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 0 0 0 0 0 0 0 0 0 % normal motion ticks 24 hours later 96 20 0 8 36 0 0 0 14 0 0 0 % ticks both with normal movement and willing to climb a finger 24 hours later 60 16 0 4 24 0 0 0 0 14 0 0 2 min exposure Total No. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 0 0 0 0 0 0 0 0 0 0 % ticks with normal movement 24 hours later 98 0 0 0 0 0 0 0 0 0 0 % ticks both with normal movement and willing to climb a finger 24 hours later 78 0 0 0 0 0 0 0 0 0 0 0 0 View Large Table 4. Results Non-treated control textile (100% cotton T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Mixtures T-shirt Long-sleeved shirt Polyester long-sleeved shirt Nylon long-sleeved shirt 60% cotton/ 40% polyester long-sleeved shirt 50% cotton/ 50% polyester T-shirt 85% coolwick/ 15% lycrasocka 76% cotton/ 21% nylon/ 3% lycrasocka 49% polyester/ 47% cotton/ 3% rubber/ 1% spandex sock 1-min exposure Total No. 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 0 0 0 0 0 0 0 0 0 % normal motion ticks 24 hours later 96 20 0 8 36 0 0 0 14 0 0 0 % ticks both with normal movement and willing to climb a finger 24 hours later 60 16 0 4 24 0 0 0 0 14 0 0 2 min exposure Total No. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 0 0 0 0 0 0 0 0 0 0 0 0 % ticks with normal movement 24 hours later 98 0 0 0 0 0 0 0 0 0 0 0 0 % ticks both with normal movement and willing to climb into a finger 24 hours later 78 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Results Non-treated control textile (100 % cotton T-shirt) Permethrin-treated textiles 100% cotton 100% synthetic Mixing T-shirt Long-sleeved shirt Long-sleeved shirt Polyester-sleeved shirt Nylon-sleeved shirt 60% cotton/ 40% polyester long-sleeved shirt 50% cotton/ 50% polyester T-shirt 85% swallowwick/ 15% lylcra socks 76% cotton/ 21% nylon/ 3% Lycre socks 49% polyester/ 47% cotton/ 3% rubber/ 1% spandex-min exposure Total No. 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 0 0 0 0 0 0 0 0 0 % normal motion ticks 24 hours later 96 20 0 8 36 0 0 0 14 0 0 0 % ticks both with normal movement and willing to climb a finger 24 hours later 60 16 0 4 24 0 0 0 0 14 0 0 2 min exposure Total No. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 0 0 0 0 0 0 0 0 % ticks with normal movement 24 hours later 98 0 0 0 0 0 0 0 0 0 0 0 % ticks both with normal movement and willing to climb into a finger 24 hours later 78 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Show large contact Irritans of a single type of Permethrin-worked lining for laboratory-bred Nymphs I. scapularis and A. americanum Ticks The percentage of ticks remaining on the analysis card after 1 min was significant (P < 0.0001) lower for the permethrin-treated textile compared to the untreated control textile, both for I. scapularis nymphs (44,0 and 98,0 %) and A. americanum nymphs (6.0 and 48,0% respectively). The irritant effect of the treated textile was even more pronounced for I. scapularis nymphs after the entire 5-min observation period, and only 2.0 % of the ticks remained on the treated textile but 94.0% remain on the untreated control textile (P < 0.0001). Observation periods above 1 min were counterproductive for the highly mobile A. americanum nymphs as >80% of ticks had become detached from the untreated control textiles already by 2 min. Most likely due to rapid discharge of A. americanum nymphs from the treated textile, the proportion of ticks showing normal movement 24 hours after contact was similar for those exposed to untreated and treated clothing. In contrast, both normal motion of I. scapularis nymphs and normal movement combined with willingness to climb a finger 24 hours after exposure significantly decreased for ticks exposed to permethrin-treated clothing compared to non-treated clothing (P < 0.0001) (Table 5). Table 5. Output A. americanum nymphs I. scapularis nymphs NTCa PTCb NTCa PTCb Total No. For ticks on test card 50 50 50 50 % ticks left on test card after 1 min 48 6 98 44 % ticks left on test card after 2 min 16 0 98 22 % ticks left on test card after 3 min 8 0 98 2 % ticks left on test card after 4 min 6 0 94 2 % ticks left on test card after 5 min 6 0 94 2 % ticks with normal movement 24 hours later 100 94 98 2 % ticks both with normal movement and willing to climb on a finger 24 hours later 96 94 74 0 Results A. americanum nymphs I. scapularis nymphs NTCa PTCb NTCa PTCb Total No. Of ticks inserted on test card 50 50 50 % ticks left on test card after 1 min 48 6 98 44 % ticks left on test card after 2 min 16 0 98 22 % ticks left on test card after 3 min 8 0 98 2 % ticks left on test card after 4 min 6 0 94 2 % ticks left on test card after 5 min 6 0 94 2 % ticks with normal movement 24 hours later 100 94 98 2 % ticks both with normal movement and willing to climb on a finger 24 hours later 96 94 74 0 See Large Table 5. Output A. americanum nymphs I. scapularis nymphs NTCa PTCb NTCa PTCb Total No. For ticks on test card 50 50 50 50 % ticks left on test card after 1 min 48 6 98 44 % ticks left on test card after 2 min 16 0 98 22 % ticks left on test card after 3 min 8 0 98 2 % ticks left on test card after 4 min 6 0 94 2 % ticks left on test card after 5 min 6 0 94 2 % ticks with normal movement 24 hours later 100 94 98 2 % ticks both with normal movement and willing to climb on a finger 24 hours later 96 94 74 0 Results A. americanum nymphs I. scapularis nymphs NTCa PTCb NTCa PTCb Total No. of ticks introduced on analysis card 50 50 % ticks left on analysis card after 1 min 48 6 98 44% ticks left on analysis card after 2 min 16 0 98 22 % ticks left on analysis card after 3 min 8 0 98 2 % ticks left on analysis card after 4 min 6 0 94 2 % ticks left on analysis card after 5 min 6 0 94 2 % ticks with normal movement 24 hours later 100 94 98 2 % ticks both with normal movement and willing to climb on a finger 24 hours later 96 94 74 0 Show Great toxicity of a single type of permethrin-treated lining for different ticks and life stages Continuous exposure to treated textile showed a general trend of decreasing sensitivity (i.e. increased probability of maintaining ability to move normally 1 h after exposure) from I. scapularis nymphs (0% with normal movement after a 1-min exposure) to A. americanum nymphs (14,0%), I. scapularis females (38,0%), D. variabilis (82 %) and A. Loss of normal movement for all ticks 1 hour after contact with the treated textile required exposures of 1 min for I. scapularis nymphs, 2 min for A. americanum nymphs, and 5 min for female I. scapularis, D. variabilis, and A. americanum ticks. Recovery of normal movement from 1 to 24 hours after contact with permethrin-treated clothing was recorded for some (8.0%) I. scapularis nymphs exposed to 1 min but not for any longer (2 or 5 min) exposure. For A. americanum nymphs, 50,0-60,0 % of the ticks were recovered normal movement from 1 to 24 hours after contact lasting 1–2 minutes, compared to only 10.0% after a 5-minus exposure. Female patterns were less evident across the shorter contact times but for all three species we noted recovery of females for 5-min contact from 1 hour after exposure (0% capable of normal movement for all species) to 24 hours after exposure (14.0-24.0% capable of normal movement). Another interesting observation was that, unlike I. scapularis and A. americanum females, shorter (1–2 min) exposure to D. variabili's females appeared to result in a slow poisoning effect resulting in gradual loss of normal motion over time: for example, after a 1-min exposure normal movement in females fell from 82% 1 hour later to 58% by 24 hours (Table 6). Table 6. Output of Nymphs Females I. scapularis A. americanum I. scapularis A. americanum D. variabilis NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb 1-min exposure Total No. of ticks exposed 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 100 14 100 38 98 98 94 82 % ticks with normal movement 24 hours later 96 8 100 74 100 44 98 96 94 58 % ticks both with normal movement and willing to climb a finger 24 hours later 60 4 98 72 94 44 46 20 50 12 2-min exposure Total No. 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 98 0 100 14 100 30 96 42 % ticks with normal movement 24 hours later 98 52 100 22 100 48 96 20 % ticks both with normal movement and willing to climb a finger 24 hours later 78 0 98 52 90 22 40 56 10 5 min exposure Total No. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 96 0 100 0 100 0 96 0 % ticks with normal movement 24 hours later 96 0 100 10 96 20 100 24 96 14 % ticks both with normal movement and willing to climb on a finger 24 hours later 68 0 100 10 92 20 44 22 60 12 Assay outcome Nymphs Honor I. scapularis A. americanum I. scapularis A. americanum D. variabilis NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb 1-min exposure Total No. of ticks exposed 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 100 14 100 38 98 98 94 82 % ticks with normal movement 24 hours later 96 8 100 74 100 44 98 96 94 58 % ticks both with normal movement and willing to climb a finger 24 hours later 60 4 98 72 94 44 46 20 50 12 2-min exposure Total No. 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 98 0 100 14 100 30 96 42 % ticks with normal movement 24 hours later 98 52 100 22 100 48 96 20 % ticks both with normal movement and willing to climb a finger 24 hours later 78 0 98 52 90 22 40 56 10 5 min exposure Total No. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 96 0 100 0 100 0 96 0 % ticks with normal movement 24 hours later 96 0 100 10 96 20 100 24 96 14% ticks both with normal movement and willing to climb a finger 24 hours later 68 0 100 10 92 20 44 22 60 12 Show large table 6. Output of Nymphs Females I. scapularis A. americanum I. scapularis A. americanum D. variabilis NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb 1-min exposure Total No. of ticks exposed 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 100 14 100 38 98 98 94 82 % ticks with normal movement 24 hours later 96 8 100 74 100 44 98 96 94 58 % ticks both with normal movement and willing to climb a finger 24 hours later 60 4 98 72 94 44 46 20 50 12 2-min exposure Total No. 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 98 0 100 14 100 30 96 42 % ticks with normal movement 24 hours later 98 52 100 22 100 48 96 20 % ticks both with normal movement and willing to climb a finger 24 hours later 78 0 98 52 90 22 40 56 10 5 min exposure Total No. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 96 0 100 0 100 0 96 0 % ticks with normal movement 24 hours later 96 0 100 10 96 20 100 24 96 14 % ticks both with normal movement and willing to climb on a finger 24 hours later 68 0 100 10 92 20 44 22 60 12 Assay outcome Nymphs Honor I. scapularis A. americanum I. scapularis A. americanum D. variabilis NTCa PTCb NTCa PTCb NTCa PTCb NTCa PTCb 1-min exposure Total No. of ticks exposed 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 100 14 100 38 98 98 94 82 % ticks with normal movement 24 hours later 96 8 100 74 100 44 98 96 94 58 % ticks both with normal movement and willing to climb a finger 24 hours later 60 4 98 72 94 44 46 20 50 12 2-min exposure Total No. 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 100 0 98 0 100 14 100 30 96 42 % ticks with normal movement 24 hours later 98 52 100 22 100 48 96 20 % ticks both with normal movement and willing to climb a finger 24 hours later 78 0 98 52 90 22 40 56 10 5 min exposure Total No. of ticks exposed 50 50 50 50 50 50 50 50 50 50 50 50 50 ticks with normal movement 1 hour later 96 0 100 0 0 96 0 % ticks with normal movement 24 hours later 96 0 100 10 96 20 100 24 96 14% ticks both with normal movement and willing to climb a finger 24 hours later 68 0 100 10 92 20 44 22 60 12 Show Large discussions Our bioassay findings indicate that permethrin-treated clothing has a promise as a personal protective measure to prevent bites of medically important ticks in the United States. This is consistent with the results of previous studies in which the use of permethrin-treated clothing reduced the risk of bites by I. scapularis, A. americanum, and D. variabilis under field conditions or simulated field conditions (Schreck et al. 1980, 1982, 1986; Mount and Snoddy 1983; Evans et al. 1990; Miller et al. 2011; Vaughn and Meshnick 2011; Vaughn et al. 2014). Of particular importance in our study is the very strong impact of permethrin-treated clothing on nymphales I. scapularis ticks, which are considered to be the primary vectors in the United States of seven human pathogens including the causative agents of Lyme disease, anaplasmosis and babesiosis (Eisen et al. 2017b, Eisen and Eisen 2018). This result is consistent with previous studies showing very high levels of protection against I. scapularis nymphs from the use of permethrin-treated military uniforms (Schreck et al. 1986, Evans et al. 1990) or permethrin-treated summer weight clothing (Miller et al. 2011). Our side by side comparison of laboratory raised and field collected I. scapulari's nymphs was prompted by an earlier study in which field-collected nymphs used in bioassays several weeks after collection appeared to experience contact irritancy to a lesser extent than laboratory-bred nymphs (Eisen et al. 2017a). In this study, field nymphs examined on the day of collection showed similar strong contact irritancy when introduced on permethrin-treated textiles as laboratory-bred nymphs (Table 1). One possible explanation for the contradictory results for field-collected I. scapularis nymphs in the same contact irritant bioassay in the two studies may be that the ability of a tick to engage in behavior to escape contact with the irritant substrate is related to its physiological status. In this study, the field nymphs were used in bioassay on the day they were collected and formed, as evidenced by their high activity even on the untreated control textiles (Table 1), powerful specimens. In the previous study where field-collected nymphs did not show contact irritant behavior when introduced on permethrin-treated textiles (Eisen et al. In 2017a) the nymphs were held in the laboratory for several weeks before use and also showed a very low level of activity on untreated control textiles. We speculate that nympheny ticks in poor physiological condition can be overcome by the toxic effects of permethrin very quickly, making them unable to participate in evasive behavior requiring strong, coordinated movement. Through our bioassay trials, both laboratory-bred and field-collected I. scapularis nymphs lost through capacity for normal movement, thus not more than minimal risk of biting by 1 hour after forced contact with permethrin-treated clothing for 1 min (Tables 2, 4 and 6). As also reported in our previous study (Eisen et al. In 2017a), some ticks recovered capacity for normal movement by 24 hours after exposure because the effect of permethrin poisoning declined. All types of permethrin-treated clothing examined were highly toxic to I. scapularis nymphs, whether the textile was 100% cotton, 100% synthetic material or mixtures (Table 4). An interesting result is that although all three types of socks investigated were highly toxic to the nymphs (0% normal-motion ticks 1 hour after forced 1-minus exposure in all three cases), a much higher proportion of ticks remained after 5 minutes in the vertical contact-relationship analysis on one of the examined socks (94%) compared to the other two socks (22-26%). Instead of lack of contactivity, we speculate that this may have been due to a looser fabric and more ‘fuzzy’ surface on the sock on which ticks were less likely to come loose, which may have led to them more often getting stuck in the fibers and not managing to escape the annoying textile. A previous field study showed that A. americanum nymphs can easily stay attached to vertically oriented socks while the subjects go (Bissinger et al. 2011). Perhaps not surprisingly, our comparison side by side between ticks and life stages showed that as ticks increased in size – from I. scapulari's nymphs to A. americanum nymphs and I. scapularis, A. americanum and D. variabili's females – a longer time contact with permethrin-treated textiles was required to achieve loss of normal movement. However, 5 min contact was sufficient for ticks of all species to lose their ability to move normally 1 hour after exposure. Much remains to be explored in terms of the impact of permethrin-treated textiles on the species and life stages of different ticks, both in terms of their innate sensitivity to permethrin and their posture, which may affect their contact level with the treated textile. For example, it says that the ventral side of the body and capitula of a smaller tick with shorter legs would more often contact the treated textile compared to a larger tick with longer legs. In addition, the specific escape behaviour of contact with a vertically treated textile, such as a sock leg or pant leg, may also be important: the typical response from I. scapulari's nymphs is to actively turn and tumble downwards (Eisen 2017a) leading to both their ventral and dorsal surfaces coming into contact with the treated textile. Our study had significant limitations, most importantly that we only investigated untouched permethrin-treated clothing and therefore have no data on how wearing and washing the garments can affect their contact irritation and toxicity to ticks. With the exception of some of the I. scapularis nymphs, the ticks used in the bioassays were reared in the laboratory and it would therefore be beneficial to confirm the results with field-collected specimens from different parts of the geographical ranges of medically important ticks. In addition, assessment of contact irritancy in permethrin-treated textiles for highly mobile ticks in females will require modification of our existing bioassay as females quickly departed from small analysis cards with untreated control textiles. Other restrictions on the bioassays and tick vigor assessment were discussed earlier (Eisen et al. 2017a). Important remaining issues regarding the possibility of permethrin-treated clothing to protect against bites of vector ticks and ultimately reduce tick-borne disease of ticks are as follows: 1) potential efficiency loss after repeated wear and wash, as observed for mosquito vectors (DeRaedt Banks et al. 2015, Faulde et al. 2016, Orsborne et al. 2016, Kittayapong et al. 2017, Richards et al. 2017); 2) the degree of acceptance for the use of permethrin-treated clothing (Richards et al. 2014); and 3) individuals' willingness to change their behavior by consistently putting on permethrin-treated clothing when entering tick habitats (Vaughn et al. 2014), especially if this includes parts of your own backyard and requires daily action. We also need to better understand which parts of the body must be covered by permethrin-treated clothing in order to achieve strong protection against ticks with different host-seeking strategies. For example, only treated shoes or socks can be reasonably effective against mobile “hunters” ticks that can make contact with people by actively seeking out their lower limbs when standing still. However, more extensive coverage of permethrin-treated garments may be required to protect against ticks that rather use an ambush strategy and essentially wait for hosts to contact them, such as nymphs of I. scapularis and the closely related Ixodes pacificcus Cooley and Kohls (Acari: Ixodidae). People greatly increase the risk of contact with nymphs of these species when they pick things up from the ground (ticks come on hands and arms) or kneel or sit on the ground or natural features like logs (ticks come on their legs) rather than just walking through the environment (Carroll and Kramer 2001, Lane et al. 2004). Consequently, adequate protection against bites from nymfal I. scapulari ticks may require wearing not only permethrin-treated shoes/socks but also permethrin-treated full length trousers and long sleeve shirts. Thank you We thank Adam Thompson (Camp Ripley Training Center) for help with field logistics. The results and conclusions of this study are by the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention. References Cited Bissinger , B. W. C. S. Apperson D. W. Watson C. Arellano D. E. Sonshine R. M. Roe , and 2011 . New field analyses and the comparative repellence of BioUD(®), DEET and permethrin against Amblyomma americanum . With. Know. Entomol. 25 : 217 – 226 . Carroll, J. F. M. Kramer, and 2001 . Various activities and footwear affect the exposure to host-seeking nymphs of Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae) . J. Med. Entomol. 38 : 596 – 600 . DeRaedt Banks, S. J. Orsborne S. A. Gezan H. Kaur A. Wilder-Smith S. W. Lindsey J. G. Logan , and 2015 . Permethrin-treated clothing as protection against dengue vector, Aedes aegypti: scope and duration of protection. Plos Negl. Trop. Dis. 9 : e0004109 . Eisen, R. J. L. Eisen, and 2018 . The black-legged tick, Ixodes scapularis: an increasing public health problem. Trends Parasitol. 34 : 295–309. : 295–309. Eisen , L. D. Rose R. Prose N. E. Breuner M. C. Dolan K. Thompson N. Connally , and 2017a . Bioassays to evaluate non-contact spatial repellence, contact irritancy, and acute toxicity of permethrin-treated clothing to nymphal Ixodes scapulari ticks. Ticks. Borne. Dis. 8 : 837 – 849 . Eisen , R. J. K. J. Kugeler L. Eisen C. B. Beard C. D. Paddock , and 2017b . Tick-borne zoonoses in the United States: persistent and emerging threats to human health. ILAR J. 58 : 319–335. : 319–335. Evans, S. R. G. W. Korch, Jr., Jr. M. A. Lawson, and 1990 . Comparative field evaluation of permethrin and deet treated military uniforms for personal protection against ticks (Acari) . J. Med. Entomol. 27 : 829 – 834 . Faulde, M. W. Uedelhoven, and 2006 . A new clothing impregnation method for personal protection against ticks and biting insects. Int. J. Med. Microbiol. 296 ( Suppl 40 ): 225 – 229 . ): Faulde, M. K. F. Pages W. Uedelhoven, and 2016 . Bioactivity and wash resistance of five commercially available, factory-treated permethrin-impregnated fabrics to prevent mosquito-borne diseases: the need for a standardised test and permit procedure. Parasitol. Travel. 115 : 1573 – 1582 . Jordan, R. A. T. L. Schulze M. C. Dolan , and 2012 . The effect of herbal and synthetic compounds on clothing as repeaters against Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae) . J. Med. Entomol. 49 : 101 – 106 . Kittayapong, P. P. Olanratmanee P. Maskhao P. Byass J. Logan Y. Tozan V. Louis D. J. Gubler A. Wilder-Smith , and 2017 . Mitigation diseases transmitted by Aedes mosquitoes: a cluster-randomized trial of permethrin-impregnated school uniforms. Plos Negl. Trop. Dis. 11 : e0005197 . Lane, R. S. D. B. Steinlein J. Mun , and 2004 Human behaviors raise exposure to Ixodes pacificus (Acari: Ixodidae) nymphs and their associated bacterial zoonotic agents in a deciduous forest. J. Med. Entomol. 41 : 239 – 248 . Miller , N. J. E. E. Rainone M. C. Dyer M. L. González T. N. Mather , and 2011 . Tick bite protection with permethrin-treated summer weight clothing. J. Med. Entomol. 48 : 327 – 333 . Mount, G. A. E. L. Snoddy, and 1983. Pressurised spray of permethrin and the dent on clothing for personal protection against the lone star tick and the American dog tick (Acari: Ixodidae) . J. Econ. Entomol. 76 : 529 – 531 . Orsborne, J. S. DeRaedt Banks A. Hendy S. A. Gezan H. Kaur A. Wilder-Smith S. W. Lindsay J. G. Logan , and 2016 . Personal protection of permethrin-treated clothing against Aedes aegypti, the vector of dengue and zika virus, in the laboratory. Plos One 11 : e0152805. Richards, S. L. J. A. G. Balanay J. W. Harris , and 2014 . Effectiveness of permethrin-treated clothing to prevent tick exposure in forest workers in the central Appalachian region of the United States. Int. The President Say hi to Res. 25 : 453 – 462 . Richards, S. L. J. A. G. Balanay J. W. Harris V. M. Banks S. Meshnick , and 2017 . Residues of effectiveness permethrin-treated clothing to prevent mosquito bites under simulated conditions. The President Say hello. 79 : 8 - 15 . Schreck, C. E. K. Posey D. Smith , and 1978 Durability of permethrin as a potential clothing treatment to protect against blood-eating arthropods. J. Econ. Entomol. 71 : 397 – 400 . Schreck, C. E. E. L. Snoddy G. A. Mount, and 1980. Permethrin and repellents as clothing impregnation agents for protection against the solitary star tick. J. Econ. Entomol. 73 : 436 – 439 . Schreck, C. E. G. A. Mount D. A. Carlson , and 1982 . Pressurised spray of permethrin on clothing for personal protection against the solitary star fortress (Acari: Ixodidae) . J. Econ. Entomol. 75 : 1059 – 1061 . Schreck, C. E. E. L. Snoddy A. Spielman, and 1986 . Pressing spray of permethrin or dent on military clothing for personal protection against Ixodes dammini (Acari: Ixodidae) . J. Med. Entomol. 23 : 396 – 399 . Vaughn, M. F. S. R. Meshnick, and 2011 . Pilot study evaluating the effectiveness of long-term permethrin impregnated clothing to prevent tick bites. Vector Borne Zoonotic Dis . 11 : 869 – 875 . Vaughn, M. F. S. W. Funkhouser F. C. Lin J. Fine J. J. Juliano C. S. Apperson S. R. Meshnick , and 2014 . Prolonged permethrin impregnated uniforms: a randomised controlled study to prevent tick bites. Am. J. Previous With. 46 : 473 – 480 . Published by Oxford University Press on behalf of the Entomological Society of America in 2018. Researchers at the Center for Disease Control and Prevention (CDC) believe that they can combat the scourge of tick-borne diseases by encouraging people to pour their clothes into a chemical substance called permethrin. In a new study, published today (May 24) in the Journal of Medical Entomology, researchers showed that permethrin-treated clothing can seriously destroy a tick's step. Stick some adult ticks on a pair of regular pants tilted at a 45-degree angle, and 100 percent of them will still cling in 5 minutes later. Stick adult ticks on a pair of tilted pants treated with permethrin, but, and 42.5 percent will tumble off completely. Even those left are seriously destroyed. The researchers found that only 25% of ticks normally moved even 24 hours after exposure. "All tested tick species and life stages experienced irritation, the 'warm foot' effect, after coming into contact with permethrin-treated clothing," said Lars Eisen, a CDC entomologist working on the study, in a statement. Permethrin is not a new chemical. You can already buy clothes coated in the items, as a manufacturer markets as retelling "Moscuits, ticks, ants, flies, chiggers and dwarfs" and persists on the clothes through at least 70 rounds in the washing machine. Drugs.com recommends it as a treatment for lice and scabs, stating that it is not known to be toxic to humans – although it can cause some mild irritation in some people. Researchers said in the paper that it is still not known how long permethrin is effective in clothing, because all the clothes they tested were "pristinian" and newly treated. But these results indicate real benefits for permethrin-treated socks, pants and other clothing, they said. Ticks are responsible for a number of serious diseases, which Live Science has previously reported, including Lyme disease. And their range seems to be spreading, probably due to climate change. This means that for researchers at the CDC, stopping them is increasingly important. Originally published on Live Science. Write a summary.
– Under ett särskilt otäckt år för fästingar har de amerikanska Centers for Disease Control and Prevention gjort ett uttalande om en möjlig metod för att förhindra spridning av sjukdomar som deras bett medför, rapporterar Live Science. Genom att bespruta kläder med ett insektsmedel som kallas permetrin tror experter att man kan få insekterna att få så kallade "heta fötter" och ramla av innan man sänder ut bakterier som orsakar borrelia och andra fästingburna sjukdomar som Rocky Mountain spotted fever. Enligt en studie som publicerades i Entomological Society of America's Journal of Medical Entomology, orsakade permetrin fästingar av flera arter att falla av kläder och, efter långvarig exponering, fick deras rörelser att bli okoordinerade. Resultaten är mer gedigna bevis för att täcka över kläder och använda insekticider är två viktiga steg för att förhindra fästingburna sjukdomar. Samtidigt ökar antalet amerikaner som får sjukdomar från små blodsugande varelser i alarmerande takt, varnar federala myndigheter. Enligt den senaste rapporten från CDC, antalet rapporterade sjukdomar orsakade av fästingar, myggor, och loppor mer än tredubblades mellan 2004 och 2016-och eftersom många sjukdomar går orapporterat, är den verkliga summan förmodligen mycket högre än de 642,602 fall som rapporterats under perioden. När det gäller borrelia kan antalet sjukdomar vara upp till 10 gånger så många som de 36.429 fall som CDC registrerade för 2016, Washington Post rapporterar. Analytiker säger att andra sådana sjukdomar – inklusive nyligen upptäckta sådana som Powassanvirus – är på uppgång i nordöstra Kalifornien och övre Mellanvästern och delvis skylla varmare väder, vilket orsakar längre fästingar årstider och utökade insektsintervall.
“In a particularly nasty year for ticks, the American Centers for Disease Control and Prevention have issued a statement on a possible method to prevent the spread of diseases that their bite entails,” reports Live Science. By spraying clothes with an insecticide called permethrin, experts believe that you can get the insects to get so-called "hot feet" and fall off before sending out bacteria that cause Lyme disease and other tick-borne diseases such as Rocky Mountain spitted fever. According to a study published in the Entomological Society of America's Journal of Medical Entomology, permethrin caused ticks of several species to fall off clothing and, after prolonged exposure, caused their movements to become uncoordinated. The results are more solid evidence to cover over clothing and use insecticides are two important steps to prevent tick-borne diseases. At the same time, the number of Americans receiving diseases from small bloodsucking creatures is increasing at an alarming rate, warns federal authorities. According to the latest CDC report, the number of reported diseases caused by ticks, mosquitoes, and fleas more than tripled between 2004 and 2016-and since many diseases go unreported, the real sum is probably much higher than the 642,602 cases reported during the period. In the case of Lyme disease, the number of diseases can be up to 10 times as many as the 36,429 cases reported by the CDC for 2016, the Washington Post. Analysts say other such diseases—including newly discovered ones such as Powassanviruses—are on the rise in northeastern California and upper Midwest and partly blaming warmer weather, causing longer ticks seasons and extended insect ranges.