Impact of mosquito coil on malaria incidence

The study is a randomized, double-blind, placebo-controlled trial to demonstrate the impact of spatial repellents against the malaria attack rates in human population in Southwest Sumba and to prove the impact associated with the entomological correlates. 45 adult men subjects in each of the four study clusters will be recruited and enrolled as the cohort. Subjects will be asked to complete a supervised malaria radical cure (regardless of blood film status at enrolment) consisting of 40mg dihydroartemisinin- 320mg piperaquine and 15mg primaquine prior to the intervention. DHA-PP is administered based on body weight (BW) targeting a total dose of 6.4 and 51.2 mg/kg BW of dihydroartemisinin and piperaquine, respectively, given in three equally divided daily doses. Doses are rounded up to the nearest half-tablet and administered orally. Primaquine is administered 30mg daily per oral for 28 days. Intervention: Four adjacent clusters in two villages in Southwest Sumba have been selected on the basis of demonstrated relatively high malaria prevalence and relative abundance of a dominant species of anopheline vector. Each of the study areas (cluster) where all these adult men subjects live will be randomly assigned to receive either active repellent (i.e. 0.0097% Metofluthrin) or a placebo in a standard mosquito coil (both manufactured to burn for 12 hours) for six months. Four coils will be placed in each house, and burned for 12 hours (commencing at 6PM each evening). Within each cluster, one of 10 randomly placed homes will be assigned to receive the opposite treatment as the community assignment to active repellent or placebo. Effects among these homes would provide some assurance of relatively uniform risk of infection and mosquito behaviours among the four sites. These embedded controls will also provide analytical leverage for discerning household- versus community-level protective effects. In other words, if placebo homes within active repellent communities enjoy substantial protection from risk, one may reasonably conclude that community coverage may be an important determinant of protective effects. Likewise, we would anticipate modest protective effects among households with active repellent in placebo communities. On the other hand, poor protection among placebo households in active repellent communities (and good protection among active coil homes in placebo communities) would point to house-specific effects and little importance of coverage in any given community. Arm 1. 90 subjects in two cluster will be given active coils. Arm 2. 90 subjects in two clusters will be given placebo coils. We reason that the difference in the sporozoite attack rate between cohorts living in areas (cluster) receiving active mosquito coils should reflect the impact of that active ingredient upon real risk of infection by biting anophelines in their natural habitats.