Factors affecting the transmission of human onchocerciasis by Simulium damnosum s l. in a fringe savanna village in Cross River State, Nigeria

Abstract

Factors affecting the transmission of human onchocerciasis by Simulium damnosum sensu lato were the focus of a study carried out in River Lewa, Etikpe, a fringe savanna village in Ikom LGA in Cross River State, Nigeria. The duration of the study was six months (August 1999 to January 2000). The thrust of the study was on ecological parameters that affected the transmission of this human scourge. Some entomological indices/parameters that are useful criteria in planning and evaluating the progress of onchocerciasis control programme were also considered. Trained flycatches working alternate hours (0700hr.-1800hr.) caught black flies used for the study. The black flies caught were either dissected fresh in the field to determine parity (physiological age) or processed in the laboratory to determine the infection/infective rates due to Onchocerca volvulus. Out of 844 black flies collected in the 30 days catching, 425 (50.4%) flies were parous. The monthly ecological parameters (that is, water pH and temperatures, dissolved oxygen, iron content, atmospheric temperatures, rainfall, relative humidity and conductivity) measured and recorded in the study area/site had no significant differences in their values (P>0.05). These observed parameters however, had fluctuations, changes and variations in values. The findings in this study, if corroborated with those of related studies based on parasitologic, ophthalmologic and socioeconomic monitoring will be useful for planning of effective treatments with ivermectin.

Keywords: transmission, human onchocerciasis, savannah, Cross River State

Mary Slessor Journal of Medicine Vol. 5(2) 2005: 59-64