Outbreak of schistosomiasis among travelers returning from Mali, West Africa.

Schistosomiasis in travelers often remains unrecognized because doctors are unfamiliar with the clinical presentation and diagnosis of this imported disease. We describe the epidemiological, clinical, and laboratory characteristics associated with an outbreak of schistosomiasis among nonimmune travelers. Of 30 travelers in two consecutive groups, 29 who had swum in freshwater pools in the Dogon area of Mali, West Africa, were followed for 12 months. Twenty-eight (97%) of those 29 became infected; 10 (36%) of the 28 had cercarial dermatitis, and in 15 (54%), Katayama fever developed. Eggs were found in 22 (79%) of the infected travelers: eggs of Schistosoma mansoni or terminally spined eggs (probably of Schistosoma intercalatum) were in the stools of 19 and 10 patients, respectively, and eggs of Schistosoma haematobium were in the urine of 7 patients. The eggs of 2 of these Schistosoma species were present in 6 cases, and in 4 cases eggs of all 3 species were found. The limited exposure of this group of travelers resulted in a high rate of infection with all three of the Schistosoma species that are prevalent in Africa. A diagnosis of schistosomiasis should be considered for any traveler with a history of exposure to fresh water in an area of endemicity. The only effective method of prevention is avoiding all contact with fresh water in these areas.