Variations under genetical control of onchocercian infection according to clinical characteristics in endemic foyers of Cameroon.

Onchocerciasis, also known as "river blindness" presents a plenum of clinic al manisfestations which vary from one individual to another, and from one area to another This large spectrum of clinical manifestations of the disea se is an indication of the complexity of the pathogenesis of onchocerciasis and suggests that many interacting factors might influence the clinical fe atures of the disease. The present study has focused on the heterogenicity of the host immune response as a plausible explanation for differences in c linical manifestations of the infection. Host genetic factors, namely HLA g enes, might play an important role in determining the nature of the immune response mounted against the parasite Onchocerca volvulus, and thus the dev elopment of different manifestations of the infection. Generic diversity of onchocerciasis was assessed in different endemic foci in Cameroon. in order to investigate the possibility that the Major Histoco mpatibility Complex (MHC) genes might be associated with the different clin ical types of onchocerciasis, 146 subjects living in three endemic areas of Cameroon were studied. They were classified in four groups. A (asymptomati c subjects), P (putatively immune subjects) L (patients with localised dise ase) and G (patients with generalised disease). The four groups differed in the distribution of HLA class II alleles as determined by Direct Heterodup lex Analysis. On the one hand allele HLA-DQA1*0501 appeared to be associate d with protection against severe onchocerciasis; on The other, allele HLA-D QB1*0201 might play an important role in the severe form of the disease.