FIELD TRIAL OF PERMETHRIN-IMPREGNATED SISAL CURTAINS IN MALARIA CONTROL IN WESTERN KENYA

A trial to determine the effectiveness of sisal eaves-curtains impregn ated with permethrin for malaria control was conducted in the malaria holoendemic western Kenya between 1991 and 1993. Indoor resting densit ies of Anopheles gambiae s.l. and Anopheles funestus were reduced. by 90.9% and 93.8% respectively in protected houses, The entomological in oculation rate (EIR) was reduced by 72% in the intervention village. T here was no significant reduction in vector longevity or survival as s hown by the sustained high sporozoite rates. Monthly bioassays for ret ained insecticidal potency of permethrin on the fibre indicated vector mortality rates above 95% over the period. Of 283 and 240 children fo llowed up from the intervention and control villages, a mean malaria p revalence of 43.2% and 52.2% respectively was observed over the trial period (p < 0.01). The prevalence rose to 73.5% and 75.7% (p = 0.541) respectively ater the removal of the curtains, No significant differen ces were observed in the mean parasite density between the groups or b etween the proportions with parasite density exceeding 2,500 per mu l and with or without fever. The prevalence of splenomegaly was signific antly lower in the intervention group compared to the control, both du ring (p = 0.005) and after the intervention (p < 0.001). There was no significant difference in the mean change in haematocrit at the end of the intervention, We observe that permethrin impregnated sisal curtai ns effectively retain permethrin, alter favourably the indoor vector d ensity and EIR, and could provide a reduction in malaria prevalence.