Effects of insecticide treated stable nets on Glossina (Glossinadae), Trypanosomiasis and other Dipterans

Abstract

A field study was conducted to assess the protection conferred to zero-grazed animals against tsetse and trypanosomiasis by surrounding a zero-grazing unit with a polyethylene net. The units were subjected to various treatments and their effect on Glossina, other biting and non-biting flies and, trypanosomiasis investigated over a period of six months. When set around a zero-graze unit at a height of 1.5m, an untreated net reduced prevalence rate of trypanosomiasis from 38% to 23.9% in the study area. In the high tsetse challenge area, the goats in the free range homestead and that from confined but without net zero-graze unit resulted in tyrpanosomisis infection rates of38% and 37% while both insecticide treated and netted zero-graze units had the infections decrease to 14% and 11% respectively. The 1% deltamethrin treated net caused significant reduction in tsetse density. This treatment yielded results that showed very high statistical significance at p<O.05 (p value = 0.001) for tsetse flies and also Tabanus species atp<O.05 (value=0.021). The 1% deltamethrin insecticide reduced the disease rate further from 23.9% in the study area Similarly, the disease risk dropped on subsequent post treatment to nil from 17% after 30 days within 1% deltamethrin treated homestead, while increasing to 33.3% at 180 post treatment days for the low tsetse challenge level and 50% within the high challenge for both free-range and confined homestead without net. This result suggests that, the net could confer protection to the zero-grazed goats effectively at low and medium tsetse challenge levels. However, treating the net with a lethal concentration of insecticide would enhance the level of protection the net confers to goats in the high tsetse challenge area