Lambdacyhalothrin treated bed nets as an alternative method of malaria control in tribal villages of Koraput District, Orissa State, India.

ABSTRACT

A village scale trial was carried out to evaluate the efficacy of bed-nets impregnated with lambdacyhalothrin, at the dose of 0.025 g/m2, in reducing malaria transmission in villages of Koraput District of Orissa, India, inhabited by tribals. The nets were distributed before peak transmission season. There was an overall decline in the parasite rate in all the age groups, six months after the supply of impregnated nets while the same increased in control village and in a village where untreated nets were supplied. The vector densities (resting and man landing) were lower in the treated village as compared to untreated and control villages throughout the study period. The reduction in the parasite rate was consistent when the reimpregnation was done at six monthly interval and the same tend to increase when the gap between the two impregnations was increased to one year. Though malaria incidence was reduced, transmission was not completely interrupted during the study period, due to outdoor transmission. The insecticidal effect of bednets was retained upto six months. Washing of bednets by the community did not affect the efficacy. The acceptance and usage was better with impregnated nets as compared to ordinary nets.