Localized onchocerciasis vector control in the Bahr el Ghazal Region of South-Western Sudan. II. Control.

Onchocerciasis vector breeding along 41 km of the Bussere River in the Wau Area of South-Western Sudan was controlled with temephos (Abate) insecticide for one annual transmission period. Vector biting and transmission was compared to the two years of precontrol data. Up to 70% reductions in vector biting and 80% reductions in transmission were recorded at sites with the highest precontrol levels. The flies invading in the control year (principally those invading from the south-west in the main part of the rainy season) were found to be much less infective - 2390 fly bites would be needed to transmit 100 larvae in the control year, compared to 1490 in the precontrol years. It was concluded that localized vector control could have a major impact on onchocerciasis transmission and that in this, and many other foci in Sudan, permanent reductions could be achieved by causeway removal and selective vegetation clearance.