ABSTRACT
The histochemical characterization of rain-forest strain of Onchocerca volvulus isolated in Akamkpa of Cross River State; Nigeria was studied. In a preliminary survey of 350 persons from eight villages; 75(21.4) were found to be positive for the parasite. Males (23.6) were more infected than the females but there was no statistically significant difference in the presence of infection by gender (p=0.506). Staining pattern of the parasite using Lead nitrate method for the demonstration of acid phosphatase activity revealed that of the six patterns; four corresponded to the enzyme types already described by some authors in West African rain-forest; and Sudan. One corresponded to the type found in Guinea savannas while the remaining did not correspond to any of the strains described elsewhere. The multiple enzyme staining patterns of Onchocerca volvulus microfilariae in the study area is indicative of polymorphic strain than that of West African strains. This variation in strain might contribute to the degree of pathogenicity and clinical manifestation of onchocerciasis in this endemic zone