CHANGES IN HUMAN SCHISTOSOMIASIS LEVELS AFTER THE CONSTRUCTION OF 2 LARGE HYDROELECTRIC DAMS IN CENTRAL COTE-DIVOIRE

The construction of large dams has been shown to increase the prevalen ce and intensity of human schistosomiasis. However, until now no study had been carried out to assess the impact of such a project in Cote d 'Ivoire, For Kossou and Taabo, two large dams which became operational in the 1970s, baseline data are available on schistosomiasis prevalen ce in the surrounding area before dam construction, so that the change s in schistosomiasis levels can be assessed. We re-evaluated the preva lence of Schistosoma haematobium and S. mansoni in November 1992, by a nalysing 548 urine and 255 stool samples, respectively, from schoolchi ldren from five villages around each lake, A marked increase in the ov erall prevalence of S. haematobium was observed, from 14% to 53% aroun d Lake Kossou and from 0 to 73% around Lake Taabo. Baseline data for S . mansoni are only available for Lake Taabo, where a prevalence of 3% was found in 1979 and where the prevalence in 1992 was still low at 2% . The construction of these two large dams therefore led to little cha nge in S. mansoni prevalence but to a significant increase in that of S. haematobium.