Epidemiology and clinical manifestations of imported schistosomiasis

Background: Several outbreaks of schistosomiasis among travellers, expatriates and military serviceman have been reported in recent years. Patients and Methods: Travel and medical histories as well as clinical features of 62 German and 21 native patients with schistosomiasis who were presented to a German outpatient clinic for infectious and tropical diseases were investigated in order to identify the risk factors leading to infection in travellers and expatriates. Results: All patients were able to remember the incidents which led to a likely exposure to cercariae of schistosoma spp. Fifty-nine German patients (95%) acquired infection in Africa, 2 (3%) in South America and one each (2% each) in the Euphrat and the Mekong River, respectively. All but 1 native patients acquired infection in Africa. The highest proportion of infection (45% in Germans and 37% in native patients) was imported from West Africa. Patients returning from this area had had either contact with tributaries of the Niger or with waters of the Volta River, notably the Lake Volta and/or its delta. The most sensitive method for detection of schistosomiasis appeared to be a combination of thorough travel history and serological testing (IHA, IFAT and ELISA) of all patients with possible infection. Conclusions: In the investigated group, most infections were acquired by travellers on a lengthy and adventurous journey or by expatriates venturing outside their normal areas of activity. Mosi patients knew that they travelled in an area endemic for schistosomiasis but were uninformed about the risks they took with their behaviour in a specific setting. Others simply could not avoid skin exposure to freshwater like backpacking tourists travelling in boats on the Niger or Congo River and native patients. Travellers to the tropics should therefore be informed thoroughly about the dangers of water-related diseases such as schistosomiasis.