Schistosomiasis Acquired in Lake Malawi.

Background: Schistosomiasis is second only to Malaria in its prevalence in the tropics. The mode of transmission of this disease is unknown to many travelers, whereas other travelers consciously choose to ignore recommendations offered by travel clinics. Methods: We present a descriptive analysis of 22 patients who presented with S. haematobium (SH) infection to two travel clinics in Israel during 1993 and 1994. Results: All 22 patients (mean age 24.2 yrs) apparently acquired SH in lake Malawi. The group contained seven couples, which indicates a very high attack rate. Three of the cases were asymptomatic, thereby causing a diagnostic delay of up to 52 weeks. Diagnosis was established in 18 cases by finding eggs in the urine, and in eight cases, by serology. Conclusion: All cases of SH diagnosed at two medical centers in Israel in 1993 and 1994 were acquired in Lake Malawi. A few of the cases were totally asymptomatic, which raises the question of routine screening. Travel clinics should warn travelers to the Lake Malawi region of this specific hazard.