Parasitology of onchocercosis in America with special reference to Venezuela
Godoy, G.A.; Volcan, G.; Medrano, C.; Guevara, R.
Boletin de la Oficina Sanitaria Panamericana. Pan American Sanitary Bureau 101(1): 1-18
1986
ISSN/ISBN: 0030-0632 PMID: 2942149 Document Number: 282000
From the time it was originally described in 1917, up until now it has not been possible to demonstrate that American onchocerciasis is produced by a species other than Onchocerca volvulus. Although some clinical epidemiological and parasitological differences have been reported between American and African onchocerciasis, the general characteristics described for adult parasites isolated from Latin American patients agree with those accepted for the genus Onchocerca and the species O. volvulus. Studies of microfilariae from skin and nodules have brought out differences in size, evolution in vectors and localization of acid phosphatase in both Latin America and Africa. This could indicate that O. volvulus is evolving into two separate species in endemic areas of onchocerciasis in Africa and Latin American. Available information on the epidemiology of onchocerciasis, parasite density in the infection, the presence of nodules, and the evolution of the disease in different endemic pockets indicate that in Latin America the infection is a relatively recent arrival and is in process of expansion. Thus, the epidemiological conditions, the limited spread of the disease, and the short history of some pockets suggest that onchocerciasis was introduced in the American continent after its discovery. Since there has not yet been any comparison amony adults of O. volvulus isolated from the endemic pockets in Latin America, nor has a uniform methodology been applied to analyze the accumulated parasitologic information, the authors stress the need to encourage systematic studies of the disease in the region.