PREVALENCE OF ONCHOCERCA-VOLVULUS NODULES IN THE SANKURU RIVER VALLEY, DEMOCRATIC-REPUBLIC OF THE CONGO, AND RELIABILITY OF VERBAL ASSESSMENT AS A METHOD FOR DETERMINING PREVALENCE

The epidemiology of onchocerciasis in much of the Democratic Republic of the Congo (formerly Zaire) is not well established. We report the r esults of an onchocerciasis rapid assessment survey carried out in 18 villages of the Sankuru River Valley in the central part of this count ry in preparation for mass distribution of ivermectin. Thirty men from each village were randomly selected and examined for subcutaneous nod ules. The prevalence of nodules among these men in each village ranged from 82.5% to 100% with a mean prevalence of 95.0%. This study also a ssessed the validity of using verbal assessment instead of physical ex amination to determine prevalence of nodules. This verbal method had a sensitivity of 93.5% and a specificity of 83.3%. High sensitivity and specificity for this method suggest that it might be a cost-effective approach to determine the prevalence of onchocerciasis over large are as without using physical examinations requiring medical personal. Thi s approach could be particularly useful when the coverage of health se rvices is poor. The use of the Global Positioning System made it possi ble to send coordinates and survey data electronically to World Health Organization personnel in Geneva for computer generation of prevalenc e maps. The use of river boats to conduct surveys and support ivermect in distribution in the Congo is discussed.