Globally there are an estimated 390 million dengue infections per year, of which 96 million are clinically apparent. In Cambodia, estimates suggest as many as 185,850 cases annually. The World Health Organization global strategy for dengue prevention aims to reduce mortality rates by 50% and morbidity by 25% by 2020. The adoption of integrated vector management approach using community-based methods tailored to the local context is one of the recommended strategies to achieve these objectives. Understanding local knowledge, attitudes and practices is therefore essential to designing suitable strategies to fit each local context. A Knowledge, Attitudes and Practices survey in 600 randomly chosen households was administered in 30 villages in Kampong Cham which is one of the most populated provinces of Cambodia. KAP surveys were administered to a sub-sample of households where an entomology survey was conducted (1200 households), during which Aedes larval/pupae and adult female Aedes mosquito densities were recorded. Participants had high levels of knowledge regarding the transmission of dengue, Aedes breeding, and biting prevention methods; the majority of participants believed they were at risk and that dengue transmission is preventable. However, self-reported vector control practices did not match observed practices recorded in our surveys. No correlation was found between knowledge and observed practices either. An education campaign regarding dengue prevention in this setting with high knowledge levels is unlikely to have any significant effect on practices unless it is incorporated in a more comprehensive strategy for behavioural change, such a COMBI method, which includes behavioural models as well as communication and marketing theory and practice. ISRCTN85307778.
With up to 3. 9 billion people in 128 countries at risk of the disease, dengue affects most of the world’s tropical and sub-tropical regions and has become the most rapidly spreading mosquito-borne viral disease[1,2]. There are an estimated 390 million infections per year, of which 96 million are clinically apparent [3]. There is currently no cure available for dengue. In 2015, the first ever dengue vaccine, Dengvaxia (Sanofi-Pasteur), came on the market despite having 60% efficacy and inducing very low protection against DENV-2[4,5]. It will also likely be several years before the vaccine is made available in low-income countries such as Cambodia. Due to the lack of a readily available vaccine or therapeutics, vector control is the only means of dengue prevention. There are an estimated 185,850 dengue cases in Cambodia annually [6,7]. Since the early 1990s, the primary means of vector control by the Cambodian National Dengue Control Program (NDCP) has been the use of the organophosphorous larvicide temephos, under the trade name Abate, applied in water storage containers [8]. However, evidence of Ae. aegypti resistance to temephos has been found in Cambodia and in other parts of Southeast Asia since 2001 [9–13]. Thus, it is clear that alternative vector control strategies are needed. Previous studies have demonstrated the most effective vector control approaches used community-based methods tailored to the local context [14–17]. In order to develop a successful strategy, it is therefore crucial to gain an understanding of current knowledge and practices regarding vector control and dengue fever in the communities. This study aimed to evaluate people’s knowledge of the dengue vector and control methods, their perceived risk of dengue fever, and to compare reported versus observed household practices. Knowledge, Attitudes and Practices (KAP), and entomology surveys were conducted to ascertain these measures and respective relations.
The study took place in Kampong Cham, a large and populous province located in central Cambodia, chosen for its high dengue incidence [18]. Being a largely rural province, the main occupation is agriculture, and it has literacy rates of 74. 8% for women and 81. 3% for men[19]. The data were collected as part of a larger cluster randomized trial set up to evaluate the effect of placing guppy fish and WHO-approved insect growth regulators in household water containers on adult female Aedes aegypti mosquito densities. The detailed protocol can be found in a previously published manuscript[20]. Briefly, 30 clusters containing one or more villages were randomly assigned to three different arms. Arm 1 received guppy fish in large water containers, the insect growth regulator in smaller containers and communication activities to promote community engagement and uptake, based on the Communication and Behaviour Impact (COMBI) approach (20). Arm 2 received only guppy fish and COMBI activities. The third arm, the control, received only standard vector control activities from the Ministry of Health which includes outbreak response in villages with three or more cases. Prior to the trial, a baseline KAP survey was administered to one participant from each of 600 randomly selected household (20 HHs per cluster in 30 clusters). Additionally, baseline entomology surveys were conducted in 1200 households (40 per cluster in 30 clusters). The KAP survey was administered to participants in September 2015, prior to the start of the interventions. The survey questionnaire (S1 Survey) was formulated using data previously collected as part of focus group discussions and in-depth interviews in a neighbouring community. The survey was piloted in a village in Kampong Cham not involved with the study (20km from study site) to assess comprehensibility and refine the formulation of questions. Following written informed consent, the questionnaire was administered face-to-face in Cambodian language to all participants, and included both structured and open-ended questions about participants’ knowledge of the dengue vector, the vector’s breeding sites and breeding prevention methods as well as dengue symptoms and treatment. The KAP survey also measured household wealth using a set of questions on asset ownership based on those included in the national Demographic and Health Survey (DHS) and adapted to the local context [21]. This information was used to generate a measure of socio-economic status (SES) which is further described below. A detailed description of the methods for both the entomology and KAP survey is provided in a previously published paper [20]. The baseline entomology surveys were done at the same time as the KAP surveys. The methodology used was based on the WHO guidelines for entomological collections [2]. All containers in surveyed households were inspected. Larvae and pupae collection in containers larger that 50L was conducted using the five sweep method [22]. The contents of smaller containers were emptied out into the sweep net. Resting adults were caught with a portable aspirator (Camtech, Phnom Penh, Cambodia): the walls in bedrooms and living spaces were aspirated in a clockwise manner up and down the wall for 10 minutes per house. Data were double entered into EpiData (EpidData Association Denmark) by an experienced external data entry team. Textual data collected in open-ended questions was translated into English and coded. All analysis was done using the statistical analysis software Stata 14. 1. Principal component analysis (PCA) using durable asset ownership was performed in order to classify participants into socio-economic quintiles [23,24]. A descriptive analysis of the different asset variables was carried out to determine their frequency and standard deviation. Variables with very low counts (<0. 01%) were excluded from further analysis. A co-variance matrix was generated for the PCA analysis as all the variables were standardized to the same unit (binary yes = 1/no = 0). From this matrix a PCA analysis was performed using the Stata PCA command. The results of this analysis were used to generate a wealth score, which was then used to classify the participants into socio-economic quintiles. In order to determine the factors influencing knowledge, Chi squared tests as well as univariate followed by multivariate logistic regressions were performed. The multivariate regression models were built using a backward elimination approach. Variables found to be have a p-value<0. 1 were kept in the model. Linear regression was used to analyse the relation between knowledge of mosquito breeding levels and reported behaviours and their observed behaviours. Knowledge of mosquito breeding was defined as the mean number of miscellaneous mosquito breeding containers identified per cluster. A negative binomial regression was used to analyse relationship between adult mosquito densities and reported behaviours. Where appropriate, robust standard errors were used to account for intra-cluster correlation. This study received approval from the Cambodian National Ethics Committee for Health Research on 9 October 2014 (reference number 0285). Additionally ethics approval was also received from the London School of Hygiene and Tropical Medicine ethics review board (reference number 10704). The trial was registered with the International Standard Randomized Controlled Trial Number Register: ISRCTN85307778.
Of the 600 participants who were administered the KAP survey, the majority were female (77. 8%), most likely because the survey was conducted during the day when the men are out working (Table 1). The ages of the participants ranged from 17 to 88 years with the mean age being 44. One per cent of participants were less than 20 years of age. In Cambodia it is common for people to marry early. Indeed, the most recent Demographic and Health Survey (2014) showed that 4. 4% of women were married by the age of 15 and 45% by the age of 20 [19]. The highest level of education attained for most of the respondents was primary school (59. 2%). Near 20% of participants had no formal education or had received the alternative education and training during the Khmer Rouge rule. The primary occupation of people surveyed was farming (70. 2%), followed by manual labour (12%). Amongst the survey participants, knowledge regarding dengue transmission, prevention methods and symptoms was high. The vast majority of people (96. 7%) were able to identify mosquitoes as being the dengue vector (Table 2). The majority of people surveyed were also correctly able to identify the dengue mosquito biting times, although, 17. 8% of participants believed that the dengue vector bites at night. The majority of respondents (95. 5%) were able to correctly identify at least one breeding site. Water storage jars, coconut shells/cans were the most commonly cited breeding sites (85. 1% and 78. 6% respectively). When asked about mosquito breeding prevention methods, 93. 9% of participants knew of at least one mosquito breeding prevention method (Table 2). Indeed, in response to an open-ended question about the types of breeding prevention methods, the most commonly cited method was the use of Abate (73% of respondents); 12. 6% of respondents only cited Abate, while 53. 7% also mentioned changing water frequently in storage jars. Almost all participants (94. 1%) knew at least one mosquito-bite prevention method. The use of nets during the day was the most commonly cited method (59%). Certain methods were strongly associated with participant’s SES level. For example, 45% (95% CI 33. 24–56. 59) of respondents from the highest SES quintile mentioned the use of fans compared with only 6% (95% CI 2. 56–15. 03) from the lowest quintile. Knowledge of dengue symptoms was much less common (Table 2). In order to distinguish dengue from other febrile illnesses, WHO recommends looking for the presence of high fever and at least two other symptoms such as rash, aches and pains, mucosal bleeding and nausea/vomiting [2]. Although 92. 1% of people mentioned fever as one of the symptoms of dengue, only 42. 7% could name three or more symptoms. Education was the main predictor of knowledge amongst participants (Table 3). After adjusting for age, respondents with at least 6 years of education had almost seven times the odds of knowing mosquitoes are the vector of dengue and four times the odds of being able to name at least one mosquito breeding site. Gender was found to be a strong predictor of knowledge regarding dengue symptoms: after adjusting for education and socio-economic status, female participants had a 63% higher odds of being able to name three or more dengue symptoms. If the participants or a member of their family developed a fever, just over 32. 2% of them would seek care from a health facility or private provider (Table 4). The majority of people would self medicate either by getting drugs from the pharmacy (i. e. paracetalmol) (18. 6%) or using cold compresses (26. 4%). Four percent of respondents mentioned they would practice “scratching”, a traditional practice that involves scratching the body with a coin to cure illness. Men were found to be more likely to seek medical attention from a health facility or private provider. Amongst the men surveyed, 43. 7% said they would seek care, compared to only 29% of women (χ2 test, P<0. 01). Linear regression analysis revealed strong evidence of a negative correlation between a person’s SES and the amount of time waited before seeking care if they or a member of their family gets a fever (Coeff: -0. 08,95%CI: -0. 12–-0. 05, P<0. 001). People in the lowest SES quintile stated that they would wait on average 2. 35 (95% CI: 2. 13–2. 56) days whereas respondents in the highest SES quintile would wait 1. 80 days (95% CI: 1. 61–1. 99) (Table 4). Almost all participants surveyed believed they are at risk of getting dengue (97. 5%) and the majority also believed that the disease can be prevented (78%) (Table 5). No significant correlation was found between risk awareness and socio-cultural variables such as education, SES, gender, occupation and age. The effect of knowledge that miscellaneous containers such as soda cans, coconut shells and tyres are breeding sites on observed practices was assessed (Table 6). It was found that the mean levels of knowledge per cluster had no effect on the proportion of households found to have such containers. Furthermore, no correlation was found between village knowledge levels of miscellaneous containers serving as breeding sites and proportion of households found to have pupae/larvae in miscellaneous containers (Table 6). Analysis was also performed on the proportion of households per village reporting disposing of miscellaneous containers and proportion of households found to have these containers. No correlation was found between these factors either. Nor was there any correlation between the levels of self-reported disposal of containers and the proportion of households with pupae/larvae in miscellaneous containers (Table 6). There was however a strong positive correlation between the proportion of households per village who reported clearing these containers and the mean number of resting female Aedes aegypti mosquitoes per household per village (coeff. 5. 28, standard error 2. 1, p-value 0. 02) (Table 6). Interestingly, the higher the number of households reporting the practice per cluster, the higher the mean number of resting mosquitoes per household was found.
Knowledge regarding dengue transmission and prevention methods was very high amongst participants, of which education was the main predictor. Villagers with at least 6 years of education had higher odds of being able to identify the Aedes biting times, biting prevention methods as well as Aedes breeding prevention methods. Although the results suggest knowledge regarding vector control measures was high, this did not translate into practice. In this setting with such high knowledge levels, an educational campaign is unlikely to have any real impact on practices. Instead a sustained behaviour change approach such as COMBI would be more appropriate. This method uses behavioural models, as well as communication and marketing theory and practice to instil change in practices. As Sokrin and Manderson stated, for any intervention to be successful, community involvement is crucial [50]. Awareness of dengue symptoms was found to be lower. To improve this, any dengue prevention program should also include education regarding dengue symptoms. Indeed, early testing and diagnosis is crucial to improving dengue outcomes, and mortality rates can be reduced when people are able to correctly identify dengue symptoms [51]. If improvements with regards to dengue prevention practices as well as symptom knowledge can be achieved, it could significantly improve dengue health outcomes in Cambodia. The views expressed are those of the authors and do not necessarily represent the official policy or position of the Department of the Navy, Department of Defense, or the U. S. Government.
The global incidence of dengue has grown dramatically over the last few decades and has become the most rapidly spreading mosquito-borne disease. To date, there is no specific treatment. A vaccine came on the market in 2015, but it will be several years before it becomes widely available and its efficacy is limited. Therefore vector control is the most important means of dengue prevention at the current time. The World Health Organization recommends the adoption of an integrated vector management approach using community-based methods tailored to the local context. In order to design appropriate strategies, it is essential to understand local knowledge, attitudes and practices regarding dengue vector control. We conducted a survey in the Cambodian province of Kampong Cham, to investigate the local knowledge levels as well as self-reported vector control practices and observed practices. We found a high knowledge of dengue transmission, and Aedes breeding and biting prevention methods. However, no correlation was found between self-reported vector control practices and observed practices. Additionally, knowledge levels did not correlate with actual vector control practices.
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Dengue knowledge, attitudes and practices and their impact on community-based vector control in rural Cambodia