Fall in incidence of guinea-worm infection in western Nigeria after periodic treatment of infected persons.

Between 1971 and 1974 a series of drug trials was conducted in 17 rural communities in western Nigeria where guinea-worm is endemic. During these trials and in subsequent years treatment, in the form of chemotherapy and/or dressing of ulcers, was given to all infected persons. A longitudinal study of infection in these villages showed a marked fall in the annual incidence over an 8-year period. The aggregate reduction in incidence in the three sectors surveyed was from 15.5% to 0.5% in sector 1, 29.8% to 0.4% in sector 2, and 20.3% to 0.0% in sector 3. The change appeared to be partly due to the treatment, which reduced the reservoir of infection and the rate of pollution of the water supply. Most of the sources of water continued to harbour Cyclops, none of which was found to be infected with Dracunculus, but which were shown experimentally to be capable of sustaining infection. The study demonstrates the potential role of therapeutic measures in controlling guinea-worm infection. It is suggested that the satisfactory measure of control that has been achieved could be increased by elimination of the Cyclops, with a view to total eradication of the disease from affected communities. Attention is drawn to the relevance of the findings for the International Drinking Water Supply and Sanitation Decade.