A school-based intervention trial using insecticide-treated school uniforms to reduce dengue infections in school-aged children

• Background: There is an urgent need to enhance our armamentarium to prevent dengue infections in children. Since dengue vectors (Aedes mosquitoes) are active mainly during the day, a potential target for control should be schools where children spend a considerable amount of their day. School uniforms are the cultural norm in most developing countries, worn throughout the day. We hypothesized that insecticide-treated school uniforms will  reduce the incidence of dengue infection in school-aged children. Our objective was to determine the impact of impregnated school uniforms on dengue incidence.Methods: A randomised controlled trial was conducted in 10 schools in eastern Thailand in 2012. Pre-fabricated school uniforms were commercially treated to ensure consistent high quality of insecticide impregnation with permethrin. The 1-h-knock-down effect and 24 h mortality of Aedes mosquitoes by the impregnated cloth was tested at baseline and then once per month using WHOPES cone test. Blood samples were taken at baseline and at the end of the school-term for the hemagglutination-inhibition assay to identify serologically confirmed dengue infections during the study period. Students were randomized into intervention schools (all students wearing impregnated uniforms) versus control schools (uniforms had the same appearance and odor, but were not impregnated).Results: A total of 1808 students in 10 schools were enrolled, mean age 10.07 years. Of these, 1651 had paired blood samples taken, which showed an incidence of new dengue infection of 3.3 % over the school term (5  months). There was no difference in the incidence of dengue infections in intervention versus control schools. Both the knock-down and mortality at baseline were close to 100%, but rapidly waned after only 8 washes to 20% e.g. after only 1 month of wearing the uniform.Conclusion: Although the results of mosquitoes’ knock-down and mortality of impregnated schools looked very promising, we did not see a protective effect of impregnated uniforms on reducing dengue infections in this school-based trial. The most likely reason for the apparent failure was the rapid waning efficacy of impregnation after washing. New technologies need to be developed to overcome rapid waning efficacy of impregnated clothing.Disclosure: This research was funded by the European Commission 7th Framework and was conducted by ‘DengueTools’ partners.

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MEDICIN OCH HÄLSOVETENSKAP  -- Hälsovetenskap -- Folkhälsovetenskap, global hälsa, socialmedicin och epidemiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Health Sciences -- Public Health, Global Health, Social Medicine and Epidemiology (hsv//eng)

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