Assessment of an Insecticidal Paint for Malaria Control

Background: Plasmodium is efficiently transmitted majorly by female Anopheline mosquitoes: Anopheles funestus and Anopheles gambiae sensus lato. A gap exists with respect to primary vector control strategies; indoor residual spray requires expertise while long-lasting insecticidal nets (LLINs) cover early night sleepers. Objectives: To cover the time between dinner and bedtime, there are commercial insecticidal paints for control of the malaria vector. It is important to monitor the efficacy of such paints. Therefore, this study was geared toward assessing the efficacy of insecticidal paint and monitoring the potency of insecticide in the paint over time. Methods: Four rooms were painted with an insecticidal paint, and another four rooms were painted with a non-insecticidal paint. Pyrethroid Spray Catch (PSC) was performed before the rooms were painted. Anopheles mosquito larvae collected from a breeding site were reared to adults in an insectary. Twenty-five-day-old non-blood fed female mosquitoes were exposed to the painted walls using a polyvinyl chloride cone. The knock-down of mosquitoes was monitored for 30 minutes. Mortality was decided by the inability of mosquitoes to move their legs or wings after 24 hours in the holding cup. A total of 11,520 mosquitoes were used for the study. Results: Five mosquitoes were collected from PSC prior to painting, and none were caught post painting. A 100% knock-down rate was observed for wild mosquitoes in the first two months of exposure. The efficacy of the paint decreased in the third month, with a knock-down rate of 92.5% in 10 minutes. Moreover, the knock-down rate was not significantly different (P > 0.05) between the Kisumu and wild strains. Although the knock-down duration increased over time, none of the exposed mosquitoes survived. Hence, the paint is considered effective in malaria control.