[Epidemiological, clinical and biological characters of savanna and forest onchocerciasis in west Africa.--Critical review and new data (author's tranls)].

Recent findings in Ivory Coast provide an opportunity to review possible factors influencing epidemiological differencies between forest and savanna patterns of onchocerciasis. Environmental factors, host factors, entomological and parasitological factors are taken into consideration. This provides evidence of two strains of parasite, associated with differences in pathogenicity, in biochemical structure, and with different species of the vector complex S. damnosum. The distribution of the severe pattern of the disease covers the area where the savanna vectors S. damnosum s.s. and S. sirbanum prevail, and extends as far as the southern limit of their range. In this respect, the terminology now in use appears to be justified by the geographical extent of the different patterns of the disease.