A community trial of ivermectin in the onchocerciasis focus of Asubende, Ghana. I. Effect on the microfilarial reservoir and the transmission of Onchocerca volvulus
Remme, J.; Baker, R.H.; De Sole, G.; Dadzie, K.Y.; Walsh, J.F.; Adams, M.A.; Alley, E.S.; Avissey, H.S.
Tropical Medicine and Parasitology Official Organ of Deutsche Tropenmedizinische Gesellschaft and of Deutsche Gesellschaft für Technische Zusammenarbeit 40(3): 367-374
1989
ISSN/ISBN: 0177-2392 PMID: 2617046 Document Number: 338637
A community trial of ivermectin was undertaken in an isolated focus of hyperendemic savanna onchocerciasis in Ghana. Since 1978 the focus has been under entomological surveillance. This was intensified from 1 September 1987 till 11 February 1988 with daily vector collection and dissection of over 30 000 flies (Simulium damnosum s.str. and/or S. sirbanum). A total of 14 991 people were treated with ivermectin on 7-10 October 1987. Skin snip surveys were done pre-treatment, and at 2 and 4 months after treatment. The mean skin microfilarial load in treated persons had fallen by more than 96% two months after treatment. During the next 2 months there was an increase in microfilaria loads which appeared to be faster than that reported in the clinical trials. The total reservoir of skin microfilariae available for transmission had been reduced by an estimated 68%-78% two months after treatment. This was consistent with the entomological results which indicated a reduction in transmission of 65%-85% during the first 3 post-treatment months. It is concluded that this study has shown for the first time that mass chemotherapy can significantly reduce onchocerciasis transmission. However, the remaining level of transmission was still unacceptably high and further studies are required to predict the long-term impact of repeated mass treatment.