A very interesting article in Malaria Journal by Ashton et al, Efficacy of attractive targeted sugar bait stations (ATBS) against malaria in Western Province Zambia: epidemiological findings from a two-arm cluster randomized phase III trial, describes a large real world trial of the efficacy of sugar baits affixed to the walls of buildings laced with clothianidin-deltamethrin (Fludora® Fusion,Bayer) at preventing malaria. Mosquitos live on nectar and other natural sugar sources. Female mosquitos only require a blood meal as extra nutrition prior to laying eggs.
This study actually looks for the incidence of malaria. Previous studies showed that such baits could reduce the prevalence of Anopheles mosquitos by up to 90%. And in this detailed study with over 120,000 target population evenly split between test and control groups, the use of ATSBs did not statistically reduce the number of cases of malaria identified clinically or by RTD tests of plasmodia. And compared to the control arm, the ATSB arm had higher reports of eye irritation, although the DSMB (Data Safety Monitoring Board) determined that these adverse events were not related to the intervention.
The authors report that results of similar studies in Mali and Kenya are in preparation. The question that probably did not cross their minds, is whether mosquitos actually spread malaria, so how would killing them affect the incidence? Could this be the reason the study did not demonstrate a statistical reduction of malaria incidence?