Sibling Species Distribution of The Vectors of Human Onchocerciasis In South East Nigeria, Epidemiological Implications and The Control Of Onchocerciasis In Nigeria

Abstract

Cytogenetic studies were carried out on the members of the Simulium damnosum complex in South East Nigeria. The studies were undertaken for a period of 12 months. Sample collections were carried out in the different bioecological zones (typical rainforest, mosaic forest, mosaic/guinea savanna and forest interphase/transitional zone) to ascertain the geographical distribution and variation in the species composition of the different vectors of Onchocerciasis in the area. Simulium larvae were fixed in Carnoy’s solution and cytogenetic analysis were carried out. The geographical distribution of the different cytospecies of Simulium damnosum complex was mapped. A total of 334 cytological identifications were made. Three out of the 9 West African sibling species, belonging to two of the Simulium damnosum complex: the S. squamosum sub-complex (228) and the S. damnosum sub-complex (56) were observed. The ICb variant of Simulium squamosum, which had been described from the River Sanaga (Cameroon), was observed for the first time in Nigeria. This suggests a probable change, in the nearest future, of the epidemiological pattern of Onchocerciasis i in the study area.