In malaria-endemic areas, residents of modern houses have less malaria than those living in traditional houses. We aimed to assess whether children in The Gambia received an incremental benefit from improved housing, where current best practice of insecticide-treated nets, indoor residual spraying, seasonal malaria chemoprevention in children younger than 5 years, and prompt treatment against clinical malaria was in place.In this randomised controlled study, 800 households with traditional thatched-roofed houses were randomly selected from 91 villages in the Upper River Region of The Gambia. Within each village, equal numbers of houses were randomly allocated to the control and intervention groups using a sampling frame. Houses in the intervention group were modified with metal roofs and screened doors and windows, whereas houses in the control group received no modifications. In each group, clinical malaria in children aged 6 months to 13 years was monitored by active case detection over 2 years (2016–17). We did monthly collections from indoor light traps to estimate vector densities. Primary endpoints were the incidence of clinical malaria in study children with more than 50% of observations each year and household vector density. The trial is registered at ISRCTN02622179.Anopheles gambiae per house per night in the unmodified houses compared with 3·60 in modified houses .In June, 2016, 785 houses had one child each recruited into the study (398 in unmodified houses and 402 in modified houses). 26 children in unmodified houses and 28 children in modified houses did not have at least 50% of visits in a year and so were excluded from analysis. 38 children in unmodified houses were recruited after study commencement, as were 21 children in modified houses, meaning 410 children in unmodified houses and 395 in modified houses were included in the parasitological analyses. At the end of the study, 659 (94%) of 702 children were reported to have slept under an insecticide-treated net; 662 (88%) of 755 children lived in houses that received indoor residual spraying; and 151 (90%) of 168 children younger than 5 years had seasonal malaria chemoprevention. Incidence of clinical malaria was 0·12 episodes per child-year in children in the unmodified houses and 0·20 episodes per child-year in the modified houses . Household vector density was 3·30 Improved housing did not provide protection against clinical malaria in this area of low seasonal transmission with high coverage of insecticide-treated nets, indoor residual spraying, and seasonal malaria chemoprevention.Global Health Trials funded by Medical Research Council, UK Department for International Development, and Wellcome Trust. There have been considerable gains in malaria control in sub-Saharan Africa, with prevalence halving and incidence of clinical disease falling by 40% between 2000 and 2015.Anopheles gambiae,A systematic review of the literature from 1900 to 2013 and a meta-analysis of 53 studies provided epidemiological evidence that good housing protects against malaria.Evidence before this studyWe searched MEDLINE and the Cochrane Library using the term “malaria” and one or more of the terms “housing”, “screening”, “malaria control”, and “vector control” for randomised controlled trials and controlled before-and-after intervention studies of housing interventions published between Jan 1, 1900, and Nov 15, 2020. A systematic review of the literature between Jan 1, 1900, and Dec 13, 2013, analysed 53 observational studies in a meta-analysis, which found 47% lower odds of malaria infection and 45–65% lower odds of clinical malaria in residents of modern houses  compared with traditional houses. An analysis of 29 malaria surveys in sub-Saharan Africa from 2008 to 2015, consisting of 284 532 children, found a 9–14% reduction in the odds of malaria infection in modern housing  compared with traditional housing. The meta-analyses are very-low quality to low-quality evidence, because even when socioeconomic status is adjusted for, there remains the possibility of residual confounding. A systematic review of house screening published in 2020, based on only two trials, reported evidence of protection of low to moderate certainty. To date, there have been three household-randomised controlled studies: the Gambian study showed that screened ceilings reduced the odds of anaemia by 49% and full screening on the doors and windows, and closing eaves  reduced the odds of anaemia by 47%(moderate-certainty evidence); the Ethiopian study reported screened doors and windows reduced clinical episodes of malaria by 62% (low-certainty evidence); and the Kenyan study found that screening the eaves reduced the odds of malaria infection by 54% (low-certainty evidence).In our study, the addition of a metal saddle-shaped roof replicated the transition in roof typology, from a thatched to a metal roof, seen in The Gambia and across sub-Saharan Africa. We closed the eaves, and the overhanging roof, because this is normal practice in The Gambia. Open eaves are the major route by which malaria mosquitoes enter houses; thus closing the eaves could reduce mosquito house entry, providing the screened doors are closed. To cool the metal-roofed houses we added two large screened windows under the eaves. Cooling the house at night could reduce the time people stay outdoors in the evening, thereby reducing exposure to outdoor-biting malaria mosquitoes, and increase the usage of bednets, because being too hot at night is a major reason given by people for not using a net. In hotter parts of sub-Saharan Africa, increasing metal roofing on a large scale, could result in mass killing of indoor-resting malaria mosquitoes during the day because the maximum temperatures of ventilated metal-roofed houses are several degrees hotter than thatched houses.Added value of this studyThis clinical trial is the first to assess the effectiveness of a ventilated screened metal-roofed house against clinical malaria compared with traditional housing, in an area of low seasonal transmission and high coverage of standard malaria control interventions—ie, insecticide-treated bednets, indoor residual spraying, seasonal chemoprevention, and prompt and effective treatment with antimalarials. In relation to malaria control, there was no additional benefit of adding a metal roof, filling the eaves, and house screening in this study, and our analysis shows that malaria incidence was higher in the intervention group.Implications of all the available evidenceAlthough there is a growing body of work that shows that good housing is associated with less malaria than traditional houses, these studies provide weak evidence because they are potentially subject to bias. Although socioeconomic status was adjusted for in the analyses, the potential for residual confounding remains. There have been few randomised controlled studies to measure the direct effect of mosquito screening on malaria transmission. The three previous studies, one of which was in The Gambia, showed clinical protection and reductions in the number of malaria mosquitoes entering screened houses compared with traditional unscreened houses. Our study was done among the poorest residents of the poorest region in The Gambia. We found higher malaria incidence in children living in modified houses than traditional houses, due to damage to the screening, and possibly due to residents staying outside the house for longer in the evening and not closing their doors until late. In these communities, alternative methods of protection are needed to prevent malaria mosquitoes entering the house and to keep the house cool. For poorly constructed houses, using eaves ribbons impregnated with spatial repellent or insecticide-treated screened windows and eaves baffles could increase protection. For better-quality houses, adding industry-quality screened doors and windows to existing houses or building new types of screened houses, with or without eaves tubes, should be explored.The hypothesis supporting housing as being protective against malaria in sub-Saharan Africa is based on the observation that 79% or more of malaria transmission occurs indoors at night;A gambiae sensu stricto, had moderate resistance to deltamethrin, a pyrethroid insecticide, but resistance was low in Anopheles coluzzii and Anopheles arabiensis.A generalised randomised complete block study, with control and intervention households randomly assigned within villages, was done in 2016–17 in the Upper River Region of The Gambia . This isPfs Sept 12, 2014). The full study protocol has been reported previously.The study was done in accordance with the International Conference on Harmonisation Tripartite Guideline for Good Clinical Practice and the Declaration of Helsinki (2000), whichever afforded the greater protection to the participants. The study was approved by The Gambia Government/Medical Research Council Joint Ethics Committee on Oct 29, 2014, (reference: SCC 1390v3) and the School of Biological and Biomedical Sciences Ethics Committee, Durham University, Durham, UK on Dec 1, 2014  for each group. All randomisation was done using code written by DJ in MATLAB, from a database of census data. Within a village, half of the selected houses were allocated to each study group, with an additional house randomly allocated to a group if there was an odd number of houses. At least four houses (two per study group), were enrolled in each village. Stratified randomisation by village reduced the likelihood of chance imbalances between study groups. Additionally, data on potential confoundersIt was impossible to conduct this study in a fully masked manner. Observer bias was reduced where feasible. Blood films were read by microscopists masked to the intervention status of the participants. Bias arising from using mosquito collectors was reduced by using standard traps that do not rely on a fieldworker to collect specimens. Mosquitoes were examined and analysed by technicians who did not know the trap location. Datasets were unmasked once data critical for the listed endpoints had been locked.At baseline, enrolled houses had a single room, thatched roofs, open eaves, and mud walls in good condition and occupants provided with sufficient insecticide-treated nets  to cover all sleeping places in all enrolled houses in July, 2016, and by the National Malaria Control Programme (NMCP) in August, 2017, as part of the national mass campaign. In the intervention group, houses with thatched roofs were replaced with metal roofs, eaves were closed, metal fixed-louvered screened doors were installed at the front of the house, and a metal-screened door at the back and screening on the window was installed, if present .21 The hPlasmodium falciparum detection only when the axillary temperature was 37·5°C or more. Presence of cough, a raised age-specific respiratory rate  or chest indrawing was also assessed, because there was concern that closing the eaves would reduce ventilation in modified houses and increase respiratory infections. During the cross-sectional surveys , a clinical examination was done on all study children, axillary temperature collected, and spleen size assessed. Children were fingerpricked for measurement of anaemia with a spectrophotometer  and an RDT was done. Thick blood films were examined by trained, experienced microscopists. Parasite counts were recorded per high-power field and 100 fields were counted before a slide was declared negative. Two slides were prepared from each individual and assessed separately by two experienced microscopists, with discrepancies resolved by a third.Incidence of clinical disease was assessed by active case detection. The children in the study were visited at home twice per week and axillary temperature taken by trained nurse field assistants, for two malaria transmission seasons (June to December) in 2016 and 2017. A rapid diagnostic test  was done immediately if the axillary temperature was 37·5°C or more, if the child had had fever since the previous visit, or was feeling unwell. A blood sample was collected for thick films for A gambiae sensu lato were identified by ELISA24To estimate potential exposure to malaria mosquitoes, mosquito collections were made using light traps from the Centers for Disease Control and Prevention, placed 1 m from the ground at the foot end of a study child's insecticide-treated net. The density of malaria vectors was assessed once a month from June to December in 2016 and 2017. Mosquitoes were identified by microscopy and counted. The presence of sporozoites in Indoor temperature was measured in 13 control houses and 15 intervention houses during the rainy season . Recordings were made in houses in the same villages every 30 min with data loggers  positioned 1 m from the floor in the centre of the room, in one unmodified house and one modified intervention house in the same village on the same dates. Data handling complied with the relevant Medical Research Council Unit The Gambia Standard Operating Procedures. Electronic Case Report Form data were collected using OpenClinica and stored on a secure server. Paper Case Report Forms were double entered into a Microsoft Access database, which after entry were password protected and accessible by DJ, JB, and MP. After database lock, the trial data manager extracted an anonymised final analysis dataset into a passworded Microsoft Access database.A gambiae sensu lato collected per light trap per night. Secondary endpoints included a broader definition of clinical malaria—ie, a positive blood slide or a positive RDT and either documented fever (axillary temperature ≥37·5°C), reported fever since previous visit, or feeling unwell; prevalence of malaria parasites; prevalence of mild anaemia (>80–110 g/L), moderate anaemia (>50–80 g/L), severe anaemia (≤50 g/L), haemoglobin concentration, and prevalence of enlarged spleens. At each home visit for active case detection, children were asked if they had slept in the house the previous night.The primary parasitological endpoint was the incidence rate of clinical malaria, with a clinical episode of malaria defined as axillary temperature of 37·5°C or more and a parasitaemia of any density. The primary entomological endpoint was the number of Serious adverse events (SAEs) in children in the study were documented. The trial followed standard definitions for SAEs agreed by consensus of the Collaborating Centres of the WHO's International Drug Monitoring Centre .We used computer-generated simulations to estimate power and found that with a 1:1 allocation ratio, one child per house followed up for 2 years would require 400 houses in each study group to detect a 35% reduction  in the rate of malaria cases with over 80% power at the 5% significance level. For the entomological endpoint, the study was 80% powered to detect a 50% reduction at the 5% level of significance. Methods for sample size calculation have been described previously.A gambiae sensu lato per light trap per night groups was calculated using negative binomial regression with a random effect for house, adjusting for ethnicity, riverbank, and burning incense (churai).Analysis was done with Stata version 15.0. Data analysis followed an analysis plan written before study completion. All analyses were done on a modified intention-to-treat basis in which all children with fewer than 50% visits in a year were not included. Data were censored for 4 weeks after a child had a documented malaria infection, and if the child had moved from the study house. If a child was absent more than half the scheduled visits in transmission season, their data were censored for that year. We compared between study groups the incidence rate of clinical malaria over the course of the transmission seasons (June to December) in 2016 and 2017, both separately and combined. Poisson regression with robust standard errors to account for repeat episodes for a child was used to compare the rates between groups, together with Kaplan-Meier plots showing time to first event by study group. An analysis adjusted for age, riverbank, month of year, and ethnicity was also carried out. The rate ratio comparing the mean number of female Parasite rates and density, anaemia prevalence and haemoglobin concentrations from the cross-sectional data were analysed by either logistic or linear regression according to whether the variable was binary or continuous. The rate of respiratory infection over the course of the two annual transmission seasons was analysed in the same way as clinical malaria.n .Entomological inoculation rate (EIR) was estimated in each study group and is defined as the number of infective bites received per person during the transmission season, and was estimated as follows: EIR=HDM × SPR × Houses classified in good condition were those with all window and door screening intact and with the doors having no gaps around the edges when shut. We hypothesised that houses where the doors were kept closed during the day were more likely to have their doors shut at night, compared with houses where the doors were left ajar. Similarly, we considered that houses with more people would have their doors opened more frequently during the night than those with fewer people.A Data Safety Monitoring Board reviewed the study procedures and results. The trial is registered at ISRCTN02622179.The funder of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report.In 2014, 91 villages agreed to participate in the study and were enrolled. The NMCP provided insecticide-treated nets to all study villages in June, 2015, and August, 2017. In July, 2017, we distributed 1513 insecticide-treated nets to all study households. Insecticide-treated net coverage increased from 397 (52%) of 762 children in June, 2016, at the start of the rainy season, to 715 (94%) of 762 children by the end of July, 2016, and coverage remained high in 2017 with 659 (94%) of 702 children in December, 2017 . Indoor Among the 859 children recruited into the study, including replacements for the original cohort, 54 were absent for at least 50% of home visits in both years and were excluded from the analysis. Therefore, the final data set included 805 children, 410 in unmodified houses and 395 in modified houses . The basThe 805 children included in the primary analysis were followed up for 654·6 child-years (330·1 in the control group and 324·5 in the intervention group) over two transmission seasons. There were 104 episodes of clinical malaria, 39 in children in the unmodified houses and 65 in the modified houses. The incidence rate of clinical malaria was 0·20 episodes per child-year in children in the modified houses and 0·12 per child-year in the unmodified houses, giving an unadjusted rate ratio (RR) of 1·68 ; the result remained significant after adjusting for age, riverbank, month of year, and ethnicity . IncidenA gambiae sensu lato were caught in study houses on 1440 trapping nights, with most being A arabiensis . Between 2000 h and 2400 h, it was 0·7°C hotter in modified houses than unmodified houses . By midnight both house typologies had similar temperatures .In modified houses, there was extensive damage to the screening on the front doors (273 [75%] of 363), but less so on back doors (85 [24%] of 360), windows on the sides of the houses (20 [17%] of 115), and screening in the gable ends  only when there were more than 20 mosquitoes entering a house at night.It would be erroneous to think that the traditional thatched-roof house represents the best typology for reducing malaria transmission. Traditional thatched-roofed houses have open eaves, the main entry point for Concern was raised that screening a house would reduce airflow and might exacerbate respiratory diseases in children. This is not the case in our study, because the incidence of respiratory illness was similar in both study groups. We also have evidence that ventilation in both groups of houses is similar.In the study villages, the levels of insecticide-treated net ownership and indoor residual spraying coverage were higher than those reached by many African countries, including The Gambia.This study has five main limitations. Firstly, the study was carried out in a subset of the population, the poorest households who were unable to afford metal-roofed houses, which might make generalisation difficult. Secondly, children in Gambian villages might occasionally sleep in other houses in the same village, and the house owner or dweller might not divulge this to not forfeit the benefits of the study. Thirdly, this study was unmasked and might be subject to differential behaviours of the field staff and participants. Fourthly, a study  suggests that the catching efficiency of light traps is greater in screened houses than control houses, because in houses with screened doors the light from the trap is seen by mosquitoes outside the house, unlike the solid doors of the control houses. If true, this scenario is likely to inflate mosquito collections in intervention houses relative to control ones. Fifthly, a cluster randomised study could have shown whether mass killing of malaria mosquitoes in intervention houses reduced malaria transmission compared with clusters of traditional houses.A perfectly screened house, where the doors are infrequently opened, will reduce the entrance of malaria vectors. Our study, however, showed that in this region of The Gambia, modifying a traditional house to provide a metal roof and screening to the poorest of the poor did not provide protection against clinical malaria compared with those living in traditional thatched-roofed houses. In addition to standard best practice, novel solutions are needed to improve protection in the home. For the poorest households, using indoor residual spraying, eaves ribbons impregnated with spatial repellent,https://www.mrc.gm/scientific-coordinating-committee/Access to clinical and entomological study data requires a formal application to the Scientific Coordinating Committee of the Medical Research Council Unit The Gambia (MRCG) and the Joint Gambian Government's and MRCG Ethics Committee in The Gambia at We declare no competing interests.


Plasmodium ovale malaria is often neglected due to its less severe course compared to Plasmodium falciparum. In 2011–2012, Belgian Armed Forces identified a cluster of P. ovale cases among military personnel after deployment in the Democratic Republic of Congo (DRC). In this retrospective, monocentric, observational study, clinical and biological features of soldiers diagnosed with P. ovale after deployment in DRC were reviewed. Species diagnosis was based on polymerase chain reaction (PCR) and/or thick blood smear. Medical records of 149 soldiers screened at the Queen Astrid Military Hospital after deployment were reviewed. Eight cases  were identified. All had positive thick smears, and seven were confirmed by PCR. Chemoprophylaxis was mefloquine in all subjects. Median time of disease onset was 101 days after return from the endemic region. Median delay between return and diagnosis was 103 days. All P. ovale bouts were uncomplicated. None had relapses after primaquine treatment. This military cohort highlights a hotspot of P. ovale in Eastern DRC. Non-specific symptoms, the less severe presentation, the lack of sensitive parasitological tools in the field and long delays between infection and symptoms probably lead to underestimation of P. ovale cases. Plasmodium ovale  is endemic to areas in Central and West Africa and in Southeast Asia [P. ovale malaria usually has a less severe clinical course when compared to Plasmodium falciparum and deadly cases are rare; therefore, it is often neglected. A systematic review of P. ovale malaria published in 2017, which included 33 research studies, describes only 18 cases of relapse of P. ovale, 22 serious cases and five related deaths [P. ovale disease among civilian travelers or deployed troops remains little known. Recently, several countries reported cases of P. ovale infections among returning military personnel [P. ovale is 82 days, in contrast to 17.5 days for P. falciparum [P. ovale diagnosis challenging.Malaria is the most common cause of fever in returning travelers and migrants from endemic regions ,2. Militast Asia . In popuast Asia . P. ovald deaths . There aersonnel ,7,8,9. Alciparum . The lonP. falciparum to be the most prevalent species, either as monoinfection  or as coinfection with P. malariae , P. ovale , or all three species  [P. ovale parasitemia was found to be rare overall, as were monoinfections with P. ovale  [P. falciparum. The diagnoses were made locally in symptomatic individuals using microscopy and/or rapid diagnostic tests (RDTs) and cases were treated with either artemether/lumefantrine (AL) or atovaquone/proguanil (AV + PG). Following this alert, military personnel belonging to the concerned detachment and any other military personnel having been deployed in DRC in the same period and having had symptoms during deployment were targeted for active malaria screening after returning to Belgium: symptomatic patients underwent RDT, thick smear and/or polymerase chain reaction (PCR) and serological tests, and asymptomatic patients were only screened with serological tests. The goal of this study was to identify in this cohort all P. ovale infections, to describe their course and to analyze the demographic, epidemiological, clinical and laboratory data of the infected personnel.From August 2011 to April 2012, a detachment of the Belgian Armed Forces was deployed in Kindu, Eastern Democratic Republic of Congo (DRC), in a region with a high estimated malaria burden, with many perennial water areas and a high density of well-adapted vectors [This was a retrospective, monocentric, observational study, in which the medical files of all subjects from the targeted cohort with at least one post-mission appointment in the Queen Astrid Military Hospital in Brussels (QAMH) were reviewed. The following data were registered: demographic information , duration of the mission, self-declared compliance to the use of mosquito avoidance measures as well as self-declared compliance to anti-malaria chemoprophylaxis and type of chemoprophylaxis used, previous stays in malaria endemic regions, results of previous malaria serological tests when available, clinical presentation during and after the mission, type of malaria infection, interval between the date of return to Belgium and onset of symptoms, interval between the date of return to Belgium and the diagnosis, diagnostic tests used and the treatment regimen received. All the patients had a complete treatment course, including antirelapse therapy with primaquine (PQ) 30 mg (base) daily for 14 days. Glucose-6-phospatedehydrogenase (G6PD) level, occurrence of adverse events and outcome were recorded.P. ovale parasites and/or;a positive thick and thin smear showing P. ovale.a positive polymerase chain reaction (PCR) for We included all patients having either:Plasmodium on thick blood smears and/or positivity of an RDT  and/or positive PCR. Species identification was based on microscopic examination (thick and thin smear) and/or PCR. For the PCR tests, DNA was extracted from 200 µL of EDTA whole blood samples with the Qiagen DNA mini kit . PCR was performed by real-time PCR with four Plasmodium species-specific probes. Two duplex reactions were run in parallel, one detecting P. falciparum/P. vivax and one detecting P. ovale/P. malariae. PCRs were performed on a SmartCycler II  [P. falciparum, P. ovale and P. malariae [The case definition of a confirmed malaria case was onset of symptoms associated with the presence of Belgium) . Detectimalariae .p value of <0.05 was considered significant.Discrete variables are represented as percentage. Continuous normally distributed variables are represented as mean ± standard deviation. In case of abnormal distribution, data are presented as median and interquartile range. Statistical analyses were conducted in SPSS 21 . A The follow-up ran from October 2011 to December 2015. Active surveillance  was performed to obtain information on the outcome. P. ovale, we analyzed the entire cohort screened at the QAMH (149 subjects). The mean duration of deployment was 85 ± 32 days (range: 7–191). Data concerning the type of chemoprophylaxis were available for all subjects. Prophylaxis consisted of mefloquine (MQ) , doxycycline (DOXY)  or AV + PG . The remaining 35 subjects (23.48%) had to switch from their initial treatment to another molecule due to side effects. Of these, 28 (18.79%) had to switch to MQ. Compliance with chemoprophylaxis was reported by 114/149 subjects (76.51%). Because of the ratio between the number of events on one side and the number of subjects receiving other medication than MQ, medication could not be entered into a regression analysis.In order to assess the malaria chemoprophylaxis against P. ovale infection and one P. ovale—falciparum mixed infection were diagnosed during the active screening period). All subjects had positive thick and thin smears. Seven cases (87.5%) were confirmed by PCR (in one case PCR was not performed). All infected subjects were men. Median age was 36 years . All patients were born in Belgium. All had been deployed in the same area. The median duration of deployment was 88 days . Five (62.5%) had previous deployments in one or several malaria endemic regions. No data regarding previous personal voyages in malaria endemic regions were available. For two subjects (25%), malaria serology had previously been performed: tests were negative for P. ovale, P. falciparum and P. malariae. No testing for P. vivax was available. None of the subjects had previously been treated for malaria. Data concerning the use of mandatory mosquito avoidance measures , impregnated clothes and mosquito nets) were available for seven (87.5%) subjects: six (75%) reported compliance. All subjects used MQ as chemoprophylaxis. Correct use of chemoprophylaxis was reported by 6/8 subjects (75%). Four subjects (50%) presented some symptoms and only two (25%) had fever during deployment; none received specific malaria treatment. All eight subjects presented symptoms after their return to Belgium. The most common symptoms were fever and chills, encountered in seven patients (87.5%), followed by headache—six patients (75%), cough, dyspnea and diarrhea—three patients (37.5%) each and abdominal pain—one patient (12.5%). Symptom onset median time was 101 (IQR = 47–334) days after return (range: 29–775) and the median delay between the return and the diagnostic was 103 (IQR = 62–339) days (range: 30–789). The timelines between the periods spent in the malaria endemic region, the apparition of symptoms, the malaria diagnosis and treatment are presented in 3 and 458 parasites/µL, respectively. The results of RDTs performed on the same day as the microscopic examination were known in six patients (75%); all were negative. All attacks of P. ovale malaria were considered uncomplicated. Admission to a hospital was necessary in three (37.5%) patients, one of which was coinfected with P. falciparum. The initial treatment of P. ovale infections was chloroquine (CQ) in five patients (%), AV + PG in two patients  and AL in one case. None had G6PD deficiency. All the patients received eradication treatment with PQ. None had relapses after PQ treatment.Eight patients met the inclusion criteria for our study  with PQ to avoid subsequent relapses related to hypnozoites. Despite a relatively high percentage of self-reported use of preventive measures, long periods in a highly endemic region with many permanent water areas and high exposure to vectors resulted nevertheless in malaria infections. The majority of the subjects in the cohort screened at QAMH had used MQ and 76.5% reported correct use of chemoprophylaxis. Therefore, it was impossible to statistically evaluate the role of MQ as protection against P. ovale infection. MQ, a methanol-quinoline drug that works as a blood schizonticide, was developed by the US military in the 1970s, in response to the increase in CQ resistance in P. falciparum in Southeast Asia [P. ovale infections [P. ovale. French military personnel experienced an increase in P. ovale infections in troops deployed to the Ivory Coast between 2002 and 2007, coinciding with the change of chemoprophylaxis from CQ with PG to DOXY. This phenomenon was interpreted as potential proof of the lower effectiveness of DOXY on P. ovale than on P. falciparum [P. malariae, P. vivax and P. ovale attacks [P. falciparum and Plasmodium non-falciparum. Further studies are needed to assess the efficacy of the current prophylactic regimens against the non-falciparum malaria parasites. Tafenoquine (TQ), a new antimalarial drug with a long half-life, was recently approved by the US Food and Drug administration for malaria prophylaxis [This study presents a cluster of eight ast Asia . It has ast Asia . While tfections . This clphylaxis . Howeverphylaxis .P. ovale, some authors reported very late P. ovale infections in travelers or returning military personnel: up to 45 months in a French patient, between 2 and 53 months after return from West Africa in 16 Spanish travelers, 47 and 69 months in two French military men returning from the Ivory Coast and up to 11 months after return from the Central African Republic in Peruvian peacekeepers [P. ovale. He received CQ followed by PQ, without subsequent attacks. This case re-emphasizes the possibility of long delays between the return from an endemic area and the occurrence of a P. ovale attack and highlights the importance of a complete travel history in patients presenting with unexplained fever, even years after a stay in the tropics.One of the interests of this series derives from the long-term medical monitoring by the Belgian military health department. While the average time between the return from a malaria endemic region and clinical presentation is 82 days for ekeepers ,18,19,20P. ovale, especially in cases with low parasitemia, further hinders the diagnosis [P. ovale infection is difficult to diagnose microscopically in the field. Because of the generally low parasitemia in patients and because the morphology of P. ovale resembles that of Plasmodium vivax, this technique requires highly trained and experienced personnel, which are not always available in the field. Moreover, microscopy itself is not always readily available. Therefore, diagnosis during deployment sometimes relies only on RDTs. Currently available RDTs have low performance in detecting P. ovale infections, especially in cases with low parasitemia [P. ovale-specific RDT available on the market, and RDTs can therefore only identify Plasmodium up to the non-falciparum level. While molecular detection methods such as PCR represent a real step forward in confirming the diagnosis, they are not routinely available and, to our knowledge, they have yet to be used as a diagnostic tool in the field.The poor sensitivity of the parasitological diagnostic tools to detect iagnosis ,22,23,24P. ovale is believed to be responsible for asymptomatic cases. Doderer-Lang et al. reported high rates of antibodies against P. ovale and P. malariae in asymptomatic blood donors from Benin [P. ovale cases.Furthermore, om Benin . AsymptoP. ovale infections need ensuring the eradication of liver hypnozoites to prevent relapses  in addition to treating the erythrocytic asexual forms that cause symptoms [symptoms ,27. The symptoms ; howeverThe relatively small number of patients and the fact that the cohort consists only of young adult males means that this group may not be representative for travelers or for populations living in malaria endemic settings. Another limitation is the lack of previous serological testing in the group. Results of previous malaria serology were only available for two subjects; both were negative. All included soldiers were born in non-endemic areas, but 62.5% had previous deployments in endemic regions and no data regarding previous personal voyages were available. Therefore, we cannot affirm with certainty that our cohort represents a non-immune population. Another important limitation is the self-reporting nature of compliance with the use of the mosquito avoidance measures and with anti-malaria chemoprophylaxis. In this study, the compliance was measured based on a self-administered questionnaire filled during the first medical visit after the mission. This may have overestimated the rate of compliance, as previously shown for anti-viral therapy  and malaP. ovale remains broadly prevalent in the DRC  [However, despite the limitations, we believe that this short report adds another piece to the puzzle of imported non-falciparum malaria. A recent study shows that 9–0.98%) . We therP. ovale in Eastern DRC. Late onset of symptoms can lead to delayed patient presentation and delayed diagnosis or misdiagnosis. The non-specific symptoms and the poor sensitivity of parasitological diagnostic tools further hinder P. ovale diagnosis. This probably leads to an underestimation of P. ovale cases in clinical practice.This military cohort reveals a hotspot of


FcγR  genes polymorphism and the clinical outcome for anti‐malarial antibody response of Plasmodium falciparum infection among Saudi children.The FcγRs genotypes have been reported to play a key role in the defence against malaria parasites through both cellular and humoral immunity. This study aimed to investigate the possible correlation between FcγR genotypes were analysed using PCR amplification methods, and measurements of immunoglobulin were determined using enzyme-linked immunosorbent assay (ELISA) technique.A total of 600 volunteers were enrolled in this study, including 200 malaria-free control (MFC) subjects, 218 patients with uncomplicated malaria (UM) and 182 patients with severe malaria (SM). The FcγRIIa-R/R131 showed a statistically significant association with SM patients when compared to UM patients. Furthermore, higher levels of IgG1, IgG2, and IgG4 were associated with the FcγRIIa-H/H131 genotype among UM patients. Although the FcγRIIa-F/V176 genotype was not associated with UM, it showed a significant association with severe malaria. Interestingly, the FcγRIIIa-V/V176 genotype offered protection against SM. Moreover, SM patients carrying the FcγRIIIa-F/F genotype showed higher levels of AMA-1-specific IgG2 and IgG4 antibodies. The FcγRIIIb-NA1/NA1 and FcγRIIIb-NA2/NA2 genotypes did not show significant differences between the UM and the MFC groups. However, the genotype FcγRIIIb-NA2/NA2 was statistically significantly associated with SM patients.The data revealed that the FcγRIIa-R/R131, FcγRIIIa-F/F176 and FcγRIIIb-NA2/NA2 genotypes are statistically significantly associated with SM patients. However, the FcγRIIa-H/H13 and FcγRIIIa-V/V176 genotypes have demonstrated a protective effect against SM when compared to UM patients. The impact of the FcyR  gene variants and anti-malaria IgG subclasses play an important role in susceptibility to malaria infection and disease outcome in Saudi children.The data presented in this study suggest that the influence of the  Plasmodium that are transmitted to humans via mosquito bites. Of these species, Plasmodium falciparum, which is most prevalent in Africa, and Plasmodium vivax pose the greatest threat to health. In Saudi Arabia, P. falciparum represents about 99% of the total cases of malaria, while only 1% of patients are infected by P. vivax. In 2019, malaria affected about 229 million worldwide and contributed to 409,000 deaths. Children below the age of five were amongst the most vulnerable groups affected by the disease ; included subjects without symptoms of the disease and showed negative results for blood film examination and PCR of the malaria parasites. Group II: Uncomplicated malaria . Group III: severe malaria . Group III included patients with severe malaria [n = 182 (30.3%)],  and P value = 0.15]  and P value = 0.026] using the heterozygotes as the reference group  and P value = 0.003]. In contrast, the FcγRIIa-H/H131 genotype was negatively associated with SM compared to UM    and P value = 0.79]. Similarly, FcγRIIIa-V/V genotype showed no statistically significant association with UM compared to MFC  using the heterozygotes as a reference group  and P value < 0.001]  and P value < 0.001]   and P value = 0.354]  and P value = 0.263] using the heterozygotes as a reference group  and P value = 0.545]  and P value = 0.009]   and P value < 0.001]  and P value < 0.001)]  and P value < 0.001, for IgG2: OR = 0.5; 95% CI (0.3 to 0.8) and P value = 0.006 and for IgG4: OR = 0.5; 95% CI (0.3 to 0.8) and P value = 0.006]  and P value < 0.001]  and P value < 0.001]  and P value < 0.001 and for IgG4: OR = 3.2; 95% CI (2.1 to 5.3) and P value < 0.001]  and P value < 0.001]  and P value < 0.001]  and P value = 0.011]  of antibodies, and maybe due to the absence of interaction in the logistic regression model.Furthermore, the analyses of the results show that the 1] Table . The curFcγRIIa (CD32a), FcγRIIIa (CD16a), FcγRIIIb (CD16b) gene polymorphism and P. falciparum AMA-1-specific IgG subclass and its importance in the susceptibility to complicated malaria infections among children in Saudi Arabia. This study is the country's first report investigating this association among children.This study aimed to evaluate the possible relationship between the variants of FcγRIIa-R/H131 genotypes polymorphism on the susceptibility to UM infection compared to MFC. This finding is in parallel with the previously published report from Eastern Sudan by Giha and co-workers, which suggested the lack of statistically significant association between FcγRIIa-R/H131 genotypes polymorphism on immunity and susceptibility to UM infection [. demonstrated a protective effect against UM for FcγRIIa-R/R131 compared with the heterozygote FcγRIIa-R/H131 genotype carriers in infants below one year of age [FcγRIIa-R/H131 in UM infection. In the present study, the logistic regression model suggests that the genotypes FcγRIIa-R/R131 are statistically significantly associated with increased susceptibility to SM infection (2.1-fold) when compared to UM patients. In contrast, the current data indicates that the FcγRIIa-H/H131 is negatively associated with SM (0.349-fold decrease) compared to UM patients. Similarly, in a former study, the authors have reported that the FcγRIIa-R/R131 genotypes are associated with SM, while the FcγRIIa-H/H131 genotypes show a significant association with mild malaria among Sudanese patients residing in East Sudan [FcγRIIa-R/R131 genotypes are associated with protection against high parasite density [FcγRIIa-H/H131 are correlated with high risk of either severe malaria or placental malaria [FcγRIIa-H/H131 in the UM patients. Nasr et al. have suggested similar results among the Fulani ethnic group that are less susceptible to severe malaria infection [FcγRIIa-H/H131 [The data of this investigation suggested that there was no significant impact of the nfection . This manfection . In contr of age . Therefo density , and the malaria –29. Intenfection . In contFcγRIIa-R/H131 polymorphism is a causative factor in the variable predisposition to malaria that is demonstrated among the different groups.The results of this study suggest that the relative reduction in malaria infection in the UM group cannot be explained solely by the magnitude and quality of the humoral response to malaria. Additional studies are needed to clarify whether the FcγRIIIa-F/V176 genotypes are not associated with UM patients compared to MFC. On the other hand, the FcγRIIIa-F/F176 genotype is statistically associated with SM compared to UM patients. However, patients carrying the FcγRIIIa-V/V176 genotypes are statistically associated with protection against SM compared to UM. The latter finding is in line with a recent Kenyan study, which shows that the polymorphisms in the FcγRIIIa-V/V are associated with protection against severe malaria and modulations in circulating IFNγ levels [FcγRIIIa-F/V176 genotypes and the severity of the disease [This study also revealed that the γ levels . In cont disease . Again, FcγRIIIa-F/F genotype are significantly expressing higher levels of AMA-1-specific IgG2 and IgG4 antibodies in the SM group compared to patients with UM. In agreement with this finding, Koene et al. have shown that the FcγRIIIa-F/F is significantly less bound to IgG1, IgG3, and IgG4 compared to the FcγRIIIa-V/V genotypes [The current study suggests that individuals carrying the enotypes .FcγRIIIb-NA1/NA1 and FcγRIIIb-NA2/NA2 genotypes. In contrast, the patients carrying the FcγRIIIb-NA2/NA2 genotype are significantly associated with SM compared to patients with UM. Recent work on children living in Western Kenya suggests that the FcγRIIIb-NA1/NA2 gene polymorphisms are not significantly associated with susceptibility to severe malaria [. have demonstrates that the FcγRIIIb-NA2/NA2 in Ghanaian children is associated with clinical malaria [FcγRIIIb-NA2/NA2 and susceptibility to severe and uncomplicated malaria among Ghanaian children [FcγR gene polymorphism and susceptibility/protection to severe malaria [The study’s results suggest that there are no statistically significant differences between UM and MFC for the  malaria . In addi malaria . In 2010children . These c malaria .FcγR genotypes polymorphism, IgG subclass and malaria infection among Saudi children. This will hopefully lead to further research in the area. Some of the studies limitations include the small sample size and the fact that the study was performed in one region of Saudi Arabia instead of it being multi-centred. As such findings need to be confirmed in a large sample size from various regions representing the whole endemic area.To the best of the authors knowledge, this is the first study in the Kingdom of Saudi Arabia which highlighted the relation between FcγRIIa-R/R131, FcγRIIIa-F/F176 and the FcγRIIIb-NA2/NA2 genotypes in increasing the susceptibility to severe malaria. Binding between the FcγR genotypes and IgG subclass results in changes in the ability of the immune cells to respond to infection through secretion of inflammatory mediators during P. falciparum infection. Further studies are underway in our laboratory to elucidate if the FcγRIIa, FcγRIIIa and FcγRIIIb genotypes polymorphism contribute to the differential susceptibility to malaria among the different study groups.This study reveals significant influence of the


Brucellosis is an important neglected bacterial zoonotic disease that has been affecting animals and humans for decades. Malaria has been considered major cause of illness in tropical areas, including Ethiopia. This study aimed to identify prevalence and risk factors of human brucellosis and malaria among patients with fever in malaria-endemic areas attending health institutes in Awra and Gulina district, Afar Region, Ethiopia.Brucella using Rose Bengal Plate Test, and the seropositives were subjected to ELISA. Data were entered using EpiData3.1 and analyses were performed using Stata SE 14.A purposive cross-sectional study was conducted among febrile patients who attended health institutes in Awra and Gulina district of Afar region from February to May 2019. 3–5 ml blood samples were collected, thick and thin blood films were prepared and examined for malaria; serum was separated and tested for anti-P. falciparum) was 4.3%  among febrile patients. Malaria was more common in males  than in female  and in non-married than in married . Being male , drinking raw milk  and boiled milk  and touching aborted fetus/discharges without protective  were independently associated with brucellosis among febrile patients.A total of 444 febrile individuals  of age ranging from 2 to 83 years  were participated in this study. The overall seroprevalence of brucellosis was 31.5%  by RBPT and 15.8%  by ELISA, as well as the prevalence of malaria (Brucella infection. So, brucellosis disease must be sought in the differential diagnosis, like ELISA test that can be used to differentiate from other febrile diseases like malaria.The prevalence of brucellosis in fever patients in this study area is higher than malaria. Consumption of raw milk and contact with animal discharge can cause significant risk of  Brucellosis is a neglected bacterial zoonotic disease that has been affecting animals and humans for years . The annBrucellosis is an occupational hazard for veterinarians, laboratory workers, slaughterhouse workers, and farmers which can be acquired through either contact with infected animals, their tissues, or animal products. The bacteria enter humans through wounds or abrasion of skins/mucous membranes during contact with infected animals and during consumption of raw or unpasteurized milk and dairy products of such milk . BrucellSince human brucellosis has wide clinical feature presentations, it mimics many communicable and non-communicable diseases like malaria, typhoid fever, typhus, rheumatic fever, joint diseases, and others. These features pose a diagnostic difficulty for brucellosis, especially in developing countries like Ethiopia, because they adhere mostly to apparent clinical signs and symptoms, as diagnostic indicators to rule out diseases. In Ethiopia, the determination of risk factors and health intervention of human brucellosis is not routinely undertaken due to the lack of effective and appropriate diagnostic facilities , 10.On the other hand, 75% of Ethiopia’s landmass is favorable for malaria transmission, leaving about 68% of the total population at risk of malaria . HoweverThe study was conducted in Kelwani primary hospital and Derayitu health center of Awra and Gulina district of Afar Region, Northeast of Ethiopia. The majority of the communities are pastoralists whose livelihoods depend on livestock, specifically camels, cattle, and small ruminants while few are practicing agro-pastoralism and growing crops by irrigation of Awash River.A health-institution-based cross-sectional study design was used to identify prevalence and risk factors of human brucellosis and malaria among patients with fever in malaria-endemic areas, attending health institutes in Awra and Gulina district of Afar region, Ethiopia, from February to May 2019. The finding of previous community-based seroprevalence of brucellosis (4.4%) in other pastoral areas of the region’s community was used to estimate the sample size . Based oAll patients older than two years who had any duration of fever and measured axial body temperature ≥ 37.5 °C during data collection period, and were willing to provide written consent/assent for participation was recruited to the study. A total of 444 respondents were interviewed in their local language (Afar language) using a structured questionnaire to collect sociodemographic characteristics, including gender, age, educational status, marital status, occupational status, residence , and potential risk factors like the type of animal owned and milk sources , ways of milk consumption either raw or boiled, the experience of milk consumption from aborted animals, exposure to aborted fetus/ materials of the animal without protective equipment, and the clinical symptoms they felt and the duration of the symptoms. A 3–5 ml of venous blood was collected from each febrile patient using a plain vacutainer tube. Thin and thick blood smears were prepared immediately from each blood sample for the diagnosis of malaria. The remaining sample was kept at room temperature for 30 min to facilitate clotting and centrifuged at 3000 rpm for 5 min to get the clear serum. All sera were separated in a labeled 1.8 ml Cryotubes, transported to Addis Ababa Federal police laboratory in a cold box, and stored at 4 °C until testing.Plasmodium species at the health institute [Malaria was detected from Giemsa stained blood films following the guideline of the Ethiopian Ministry of Health for the diagnosis of malaria and identification of nstitute .Two types of serological tests were used to determine the seroprevalence of brucellosis.Brucella antibodies in the Addis Ababa Federal police laboratory. As previously described [Brucella antigen suspension was mixed with positive and negative controls and serum on a circular test card. If a specific antibody to Brucella antigen is present in the serum, it reacts with the antigen suspension to produce visible agglutination after shaking on a low-speed shaker for four minutes. No agglutination indicates an absence of specific antibodies to Brucella antigens. All sera positive for Brucella antibody using RBPT were transported to Armeaur Hansen Research Institute (AHRI) to confirm the anti-Brucella antibodies by IgG ELISA. According to the manufacturer’s guideline , qualitative anti-Brucella IgG ELISA was determined based on the principle of the spectrophotometric enzyme immunoassay at the wavelength of 450 nm. The calculated absorption for the patients’ sera was compared with the value of the cut-off standard, 10 IU/ml [The sera were screened using Rose Bengal Plate Test (RBPT) and positive reactors were further subjected to ELISA. All sera and RBPT reagent and controls were taken out from the refrigerator and kept at room temperature for 30 min to screen for anti-escribed , the smo10 IU/ml . If the Descriptive analysis was used to summarize the data in the form of frequencies and percentages. Pearson Chi2 test was used for testing relationships between brucellosis and malaria infection with each demographic characteristic of study participants. Univariate logistic regression analyses were conducted to establish the association of the putative risk factors with brucellosis and odds ratio at 95% confidence intervals (CI) was considered. All risk factors significant at univariate analysis were considered for multivariate logistic regression analysis to determine the independent association between risk factors and brucellosis at 95% CI. A P-value below 0.05 was considered statistical significance.This study received ethical clearance from the Ethical Review Board of the Department of Medical Laboratory Science, College of Health Sciences, Addis Ababa University (DRERC/410/19/MLS). Permission was obtained from Derayitu Health center and Kelwani Primary Hospital. Participants’ information sheet, which contains the objective of the study, inclusion/exclusion criteria, the required data and methods of data collection as well as informed consent/assent document, was prepared in the Amharic language, the national language of the country. Then, the elements of the participants’ information sheet initially were orally translated to the local language (Afar Language) and described to each of the study participants or parents in the case of children under 18 years by trained local health personnel. Informed consent/assent was obtained from each participant and/or parent for children aged between 12 and 18 years. A blood sample was collected under aseptic conditions by experienced laboratory technicians. Study participants who were found positive for malaria were treated according to malaria treatment guidelines and the rest were treated with different antibiotics accordingly as per clinician presumptive diagnosis.A total of 444 febrile individuals , with the age range of 2 to 83  years participated in the study, with the majority, 241 (54.3%) of the participants between 15–29 years old. Among 444 febrile study participants, 249 (56.1%) were agro- and/or pastoralists 201 (45.3%) were illiterate, 313 (70.5%) married, and 347 (78.1%) were rural residents  by RBPT. From all seropositive, 70 (50%) were found positive by ELISA. The combined seroprevalence was found 70/444 . Brucellosis was frequently detected in males than in females , in illiterate than in primary school and above educational status  and in rural residents than in urban residents . The brucellosis disease was more frequently detected among pastoralists than among a group that holds agro-pastoralist, daily laborers, governmental workers, and students . Similarly, large ruminant owners had the highest rate of brucellosis, followed by small ruminant owners, more than one animal type owners, and camel owners when compared to those who do not have any animals . On the other hand, brucellosis was more frequently detected among malaria positive  than among malaria negative  but the difference was not statistically significant (p = 0.197)  by microscopic detection of Giemsa stained thick and thin blood films. Malaria cases were more common among males than females  and non-married than married . The frequency of malaria was found high in the age group between 2 and 14 years   tested for malaria, 19  were found positive for malaria  respectively, drinking milk from aborted animal  and touching aborted fetus/discharges without protective equipment , were significantly associated with the occurrence of human brucellosis among these febrile patients  –4.26, p < 0.002), drinking raw milk , boiled milk  and touching aborted fetus/discharges without protective  were associated with higher odds of having brucellosis infection among febrile patients  positive by screening test (RBPT) for brucellosis, of which 70/140 (50%) of them were confirmed positive by ELISA. Among the fever patients in this study, the overall combined seroprevalence rate of brucellosis was 15.8% , and the prevalence of malaria was 4.3% . This study shows that in this malaria-endemic area, the prevalence of brucellosis among people with fever is higher than that of malaria. The possible reason for this difference is that malaria control has produced effective reductions in malaria incidence. On the other hand, human brucellosis has not yet been considered an important public health disease; consequently, the area was affected by febrile brucellosis.P. falciparum was 4.3% and P. vivax was not detected. The result is lower than the previous health-institution-based studies carried out before the full implementation of the intervention programs in Ethiopia such as in 2013 (51.5%) [P. falciparum which is the most severe of malaria may impact the health of the community in this study area.The prevalence of  (51.5%) , in 2015 (51.5%) , and in  (51.5%) . This si (51.5%) . Malaria (51.5%) , sustainBrucella species, and the type of diagnostic tests used.The prevalence of human brucellosis in this study area is in agreement with the findings from febrile individuals of different Sub-Saharan African countries like Tanzania (15.4%), Northern Uganda (18.7%), and Northeastern Kenya (13.7%) –27. ThisThe study identified residential area and gender as important risk factors for human brucellosis. Rural residents and being male who lived in this area were about three and a half and five and half times more likely to be seropositive for brucellosis compared to urban residents and females, respectively. This finding is in agreement with other studies in Uganda and Egypt , 31, whibrucella and other zoonotic infections.This study also identified consumption of raw milk and contacts with aborted fetus/discharges without protective equipment to be associated with brucellosis, which is in line with another couple of study findings in Uganda , 32. ThiThis study has a few limitations. First, since it was a purposive cross-sectional study, we recruited only febrile individuals that visited health facilities that left behind apparently healthy chronic patients, and during self-reporting, there would be recall bias by the participants for possible factors associated to the occurrence of brucellosis in humans that weaken the inference of the finding. The other limitation is the test being based on serological tests; the reported seroprevalence of brucellosis could be difficult to differentiate from the previous infection.Brucella infection. So, the brucellosis disease must be sought in the differential diagnosis, like ELISA test that can be used to differentiate from other febrile diseases like malaria. Study is recommended to address asymptomatic brucellosis and to determine the circulating Brucella species and drugs profile, as well as the similarities and differences of species between humans and animals.The prevalence of human brucellosis in fever patients in this study area is higher than the prevalence of malaria. The consumption of raw milk and contact with animal discharge can cause a significant risk of


Plasmodium malariae/Plasmodium brasilianum, Plasmodium vivax, Plasmodium simium, and Plasmodium falciparum has been reported in New World primates (NWP). Specifically in Costa Rica, the presence of monkeys positive to P. malariae/P brasilianum has been identified in both captivity and in the wild. The aim of the present study was to determine the presence of P. brasilianum, P. falciparum, and P. vivax, and the potential distribution of these parasites-infecting NWP from Costa Rica.In South and Central America, The locations with PCR (Polymerase Chain Reaction) positive results and bioclimatic predictors were used to construct ecological niche models based on a modelling environment that uses the Maxent algorithm, named kuenm, capable to manage diverse settings to better estimate the potential distributions and uncertainty indices of the potential distribution.Plasmodium presence was conducted in 384 samples of four primates , from across Costa Rica. Three Plasmodium species were detected in all primate species . Overall, the infection prevalence was 8.9%, but each Plasmodium species ranged 2.1–3.4%. The niche model approach showed that the Pacific and the Atlantic coastal regions of Costa Rica presented suitable climatic conditions for parasite infections. However, the central pacific coast has a more trustable prediction for malaria in primates.PCR analysis for the Plasmodium transmission in NWP coincide with regions where most human cases have been reported. These regions were also previously identified as areas with high suitability for vector species, suggesting that enzootic and epizootic cycles occur.The results indicate that the regions with higher suitability for The online version contains supplementary material available at 10.1186/s12936-021-04036-y. Plasmodium, mostly transmitted by bites of Anopheles mosquitoes. The genus Plasmodium includes more than 250 different species that infect mammals, reptiles, birds, and amphibians [Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium ovale. More recently, Plasmodium knowlesi and Plasmodium cynomolgi has been implicated as a cause of human malaria [Anopheles mosquitoes. There are more than 400 different species of Anopheles mosquitoes, and approximately around 30 of these determined as malaria vectors of major importance [Anopheles were detected, being Anopheles albimanus the main vector recognized [Malaria is a vector-borne disease caused by protozoa of the genus phibians . Four sp malaria . Non-hum malaria , 5. Thisportance , 7. In Ccognized .Plasmodium brasilianum and P. simium have been reported in New World primates (NWP) of the Cebidae family and are difficult to distinguish from the human P. malariae and P. vivax, respectively [Plasmodium brasilianum was identified in at least 35 species of NWP in Central and South America [Plasmodium brasilianum resembles P. malariae morphologically, and are nearly genetically identical, differing in mutations expected within a species. Naturally acquired infection with P. brasilianum has been found in humans [P. malariae/P. brasilianum in human samples, the sequences showed a 99% identity with sequences of Plasmodium species isolated from NWP in French Guiana. In Costa Rica, the analysis of genetic diversity of the monkey samples positive to malaria revealed that the P. malariae/P. brasilianum parasite found in one howler monkey was identical to that recently found in humans residing Costa Rica [Plasmodium simium has been determined principally in the Atlantic Forest in southern Brazil, considered specific of NWP, and related, but distinct from P. vivax, as established recently [P. vivax outbreaks reported in the Atlantic Forest of Brazil  were infections caused by P. simium transmitted from monkeys to humans by mosquito bites. Plasmodium falciparum has been detected in NWP (Aotidae) from Brazil [Plasmodium has been determined both in captivity and in wild NWP. In 2006, the first report of six howler monkeys  positive to P. brasilianum [P. malariae/P. brasilianum [ectively . Plasmod America –11. Plasn humans . In Costn humans  reportedrecently . Brasil recently  suggest  2015, 20 were infm Brazil , and it m Brazil . In Costsilianum  was publPlasmodium elsewhere in Costa Rica could represent a spillover risk. New World Primates represent interesting populations for study, because of its distribution in areas of ideal weather and altitude in the country for the presence of vector-borne diseases, as is the case for malaria. The constant use of human altered environments by these monkeys as well as its interaction with people [Plasmodium between populations of monkeys or humans by way of mosquito bites. This investigation proposes to determine the presence and potential distribution of climatic suitability for the transmission of Plasmodium  in the four species of natural inhabitants of NWP of Costa Rica: howler , white-faced (Cebus imitator), squirrel (Saimiri oerstedii) and spider (Ateles geoffroyi) monkeys. It has been highlighted that infection prevalence and transmission of blood parasites such as avian malaria are affected by environmental conditions and that this information is crucial to develop better risk maps [Worldwide maps of malaria distribution show that Costa Rica is one of the countries with suitable conditions for stable malaria transmission . Howeverh people , may favisk maps . It is iThe NWP were all collected from 2000 to 2012 in forest areas, and samples from captive animals were gathered from zoos and rescue centres of Costa Rica. The geographic coordinates of each location were obtained using a GPS unit. The animals were captured in situ by chemical immobilization with darts , and compressed gas rifle  for individuals over long distances, or blowgun for individuals located at close range. Anesthetics used were Zoletil 50 (3.3–11 mg/kg) or ketamine (5–20 mg/kg), in combination with Xylazine (0.5–2 mg/kg) , 24. As Plasmodium spp. was amplified. The PCR products were visualized in 2% agarose gel electrophoresis, stained with Gel Red . As positive control P. malariae-DNA, P. vivax-DNA, and P. falciparum-DNA were used, which were donated by the Primatology Institute of the University of Washington, Seattle, USA, and Malaria Reference Center, INCIENSA, Tres Ríos, Costa Rica. Free nuclease water was used as a negative control. Samples with bands of 269 bp , 499 bp (P. vivax), and 395 bp , were considered positive. Some positive samples were subsequently re-amplified, and the amplicons with adequate concentrations were sequenced with the same diagnostic primers to confirm the PCR results. Sequences derived from this study were aligned together with Plasmodium sequences from Genbank then trimmed to a common length of 269 bp, 499 bp, or 395 bp.Total DNA was extracted from all blood samples using the DNeasy Blood & Tissue Kit , according to the manufacturer’s instructions and using 100 ul of blood. Polymerase Chain Reaction (PCR) was carried out as previously described , where aPlasmodium lineages were lumped together to generate a single supraspecific Plasmodium niche model as a valid taxonomic unit to model the ecological niche [Plasmodium lineages showed no specificity with the four NWP species Plasmodium niche model of NWP of Costa Rica, the Maxent's machine learning algorithm [To construct the lgorithm  was usedlgorithm , 33. Duelgorithm . The stalgorithm  was usedlgorithm . By doinPlasmodium sp., were included in a primary dataset. Duplicated occurrences were eliminated . Afterwards, the aim was to reduce the effects of spatial autocorrelation by thinning the occurrence of records using a distance filter of 5 km between records with the spThin R package [A total of 21 occurrences of primate individuals that tested positive for  package . The fin package . The lat package .M” is an essential component in the biotic, abiotic, and movement (BAM) model [The accessible area “M) model , that deM) model . To shapM) model , as descM) model .Plasmodium spp in Costa Rica. For this, WorldClim 2 was used because WorldClim data performed substantially better than other available climatic data in various modelling purposes  [Fifteen variables were included in the modelling framework to construct the ENM of lim.org; ). From tlim.org; . In orden < 0.8) , 45, andn < 0.8) . All biokuenm R package [ENM was constructed using the maximum entropy algorithm implemented in MaxEnt version 3.4.1 via the  package . In the  package . The bes package . Partial package .E = 5%) [Plasmodium spp were created using ten replicates by bootstrap, with logistic outputs, and these models were transferred from the accessible area “M” to the projection area “G.”The omission rate is a threshold that considers an estimate of the likely amount of error among occurrence data and thus removes 5% of occurrences with the lowest suitability values (E = 5%) . The AICE = 5%) . Models E = 5%) . The criE = 5%)  to selecM” (10% reference points sampled) with that in the projection area using the MOP function [kuenm R package. The risk of extrapolation analysis defines the areas with strict extrapolation  to avoid the risk of over-prediction in non-analogous environments.To identify extrapolation risk in the model transfers, a mobility-oriented parity (MOP) analysis was performed comparing the environmental breadth of predictors within “function  availablAlouatta palliata), 132 white-faced monkeys (Cebus imitator), 50 squirrel monkeys (Saimiri oerstedii), and 72 red spider monkeys (Ateles geoffroyi) . The four species of NWP were found positive. Plasmodium positivity by monkey species was the following: howler (7.7%), white-faced (7.6%), squirrel (10%), and red spider (11.1%)  in the Central Pacific region of Costa Rica in 2010, and six  living in the Northern regions in 2005 , and cattle pasture in unprotected areas, as well as tourism and real estate development disrupting the connectivity between forest patches. Land use and climate change favour the presence of potential vectors and affect the composition of wildlife communities, which influence human and animal exposure to the parasite as well as its prevalence both at a spatial and temporal level [Plasmodium species throughout the years was not observed, P. falciparum was the species most often found, followed by P. malariae/P.brasilianum, and P. vivax. When compared to the cases reported in humans of Costa Rica, most human cases reported are P. vivax, followed by P. falciparum, and specifically P. malariae/P. brasilianum cases are very rare [Plasmodium infections in NWP and humans, although a greater presence of positive individuals in areas of historically high incidence of human cases [ changes . The stual level . A definery rare , and werery rare . It is nan cases  was deteP. falciparum and P. vivax have not been reported in NWP of Costa Rica. The presence of P. falciparum in NWP has already been reported in Brazil [Plasmodium vivax was the most often detected species in human cases of Costa Rica. In 2007, 99% of reported malaria cases were P. vivax, and the remaining 1% was P. falciparum [Plasmodium simium, a sister species of P. vivax, has been reported to date only in NWP of Brazil, and was recently determined as a monkey specific species, distinct from P. vivax, by a differential diagnosis developed for both species [P. simium which has adapted to sylvatic reservoirs, but can infect humans due to the presence of vectors such as Anopheles cruzii with the ability to feed on both monkeys and humans. Outbreaks of malaria diagnosed in 2015 and 2016 in Costa Rica were reported as P. vivax, it is important to investigate in future studies if native cases reported in the Atlantic region, were infections caused by P. vivax or by P. simium, transmitted from monkeys to humans by mosquito bites [P. malariae parasite found in one howler monkey was identical to that recently found in humans residing Costa Rica [Plasmodium in NWP (Aotidae and Cebidae) [Anopheles present in Costa Rica [In agreement with the proposed possibility that non-human primates may be natural reservoirs for human malarias , 53, P. n Brazil , 17, andlciparum . Plasmod species  (de Alva species  propose sta Rica . For thiCebidae) –57 it issta Rica , which mAn. albimanus is the main vector associated with the transmission of malaria in humans in Costa Rica [Anopheles species has been reported [An. neivai (Kerteszia subgenus) associated with the transmission of malaria in NWP and humans in Brazil, since its ability to be found both in the forest canopy and at ground level [It is expected that the vectors between monkeys and humans differ in their distribution by the habitats used . Althougsta Rica , the prereported . Includind level . All posnd level , 61.Plasmodium occur in order to a better to enhance the understanding of the relationship between the geographical and environmental correlates with malaria transmission, that can help plan more effective control strategies, using the natural environment cycles as disease sentinels.Here in, a first geographical approach was developed to understand the spatial patterns of malaria transmission in NWP and how this can be related with human malaria in Costa Rica. The modelling framework used allowed for the identification of areas where spillover is possible providing the coincidence between areas with climatic suitability for the primate parasite transmission with the presence of human populations. Modelling parasite-infected or diseased individuals is a challenging task since the natural infection prevalence is often low. In the presented case, several records were available of monkeys, but only 8% of infection prevalence, so there was a reduced dataset for model calibration. Although a straightforward framework was used to reduce the effect of sampling size on model quality, it was considered that for some regions the predictions must be taken with caution  based on a limited representation. Since maps were produced for model uncertainty and the extrapolation risk, areas were identified where the model used was more or less robust. The authors encourage more research to document the spatial locations where primate infections with Anopheles in Latin America [Anopheles in places where NWPs are distributed. As well integrate the taxonomic determination of mosquitoes and infectivity for Plasmodium into research to establish which of these species are acting as malaria vectors for NWP, and to confirm the presence of P. simium in the country. Finally, it is recommended that an exhaustive comparison be made between free-living individuals and individuals kept in captivity to determine if captivity favours the presence of positive individuals.Due to the great diversity of  America , it is aAdditional file 1: Fig. S1. Omission rates and AICc values for all, non-significant, and selected “best” candidate models for the Plasmodium sp.Additional file 2: Fig. S2. Maps of the best models according to the performance evaluation. Maps order are the same as Table