The evolution of ocular onchocerciasis in the Volta River Basin Area over a period of five years of vector control.
The results of an ophthalmological evaluation conducted in seven West African savannah villages before and after 5 years of vector control, were analysed to determine the effect of an interrupted or greatly reduced transmission of Onchocerca volvulus on the evolution of ocular onchocerciasis. Cross-sectional data showed a significant reduction of the prevalence of ocular onchocerciasis in five of the villages, and the rates of irreversible ocular lesions and blindness were generally lower after 5 years of vector control. A longitudinal study of a defined population showed that the ocular status of most patients with ocular onchocerciasis remained stable or improved over the 5 year period, particularly in lightly infected cases. The evolution of ocular onchocerciasis showed a deterioration in a minor proportion, restricted to cases of already existing severe lesions, resulting in blindness. A comparison of ophthalmic data from adjacent areas without vector control, indicates that a five year period of vector control may reduce the risk of developing eye lesions or blindness due to onchocerciasis by 50%.
D000293:Adolescent; D000328:Adult; D000354:Africa, Western; D001766:Blindness / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005128:Eye Diseases / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D006801:Humans; D007300:Insect Control; D007303:Insect Vectors; D007634:Keratitis / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009855:Onchocerciasis / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission; D013997:Time Factors