Ocular onchocerciasis and intensity of infection in the community. III. West African rainforest foci of the vector Simulium sanctipauli
Dadzie, K.Y.; Remme, J.; Baker, R.H.; Rolland, A.; Thylefors, B.
Tropical Medicine and Parasitology Official Organ of Deutsche Tropenmedizinische Gesellschaft and of Deutsche Gesellschaft für Technische Zusammenarbeit 41(4): 376-382
1990
ISSN/ISBN: 0177-2392 PMID: 1963702 Document Number: 350862
The community pattern of ocular onchocerciasis is described for 11 villages from the forest area in Cote d'Ivoire where S. sanctipauli is the principal vector. An analytical methods is applied which relates indices of ocular onchocerciasis with the Community Microfilarial Load (CMFL) and compares the results with the ocular onchocerciasis pattern found in the West African savanna. In spite of high transmission levels as estimated by entomological indices, the CMFLs were relatively low which complicated the characterization of the ocular disease pattern. Nevertheless, it could be shown that ocular onchocerciasis is less severe in the Sanctipauli forest than in the savanna, even after correction for differences in CMFL. The prevalence of onchocercal eye lesions and blindness were low and advanced sclerosing keratitis was completely absent. The differences were explained by presuming strain differences of the parasite Onchocerca volvulus. For given CMFLs the mean microfilarial loads in the eye were significantly lower than in the savanna which suggests that the parasite strain in the Sanctipauli forest is less invasive to the eye. Ocular microfilarial loads were too low to determine if the parasite is also less pathogenic to the eye, as has been concluded previously for foci of S. yahense, but this possibility cannot be excluded.