Simulium vector flies (so called blackflies)
Simulium damnosum s.l. is the main vector of human onchocerciasis in Cameroon and is also the main local vector of Onchocerca ochengi. There are at least 4 main (sub-)species found in the rain-forest and savanna:
Simulium sirbanum: A small and very pale species, only found in the Sudan savanna.
Simulium damnosum sensu stricto: Savanna mainly, but now also found since 1986 in the forest near Kumba
Simulium squamosum: Forest and Guinee-savanna. There are probably several subspecies of S. squamosum; very dark ones in the forest and pale ones in the savanna.
Simulium mengense: Forest only, but occasionally also observed in the savanna
These species can be distinguished by their morphology (see figure), as they come in the adult stage to bite on man.
More precisely, identification can be done on the larval salivary gland chromosomes (“cytotaxonomy”).
We examined over 100 Simulium breeding sites in varius bioclimatic zones of Camerroon. The results of the cytotaxonomic identification of the larvae found is given here.
Other Simulium flies, like S. bovis, S. dukei, S. griseicolle, S. adersi etc. are occasinally caught on man. Filarial larvae are found in S. bovis (vector of O. ramachandrini, O. ochengi and possibly also O. volvulus) and S. griseicolle (filarial species not yet identified).