Schistosomiasis, or bilharzia, is a parasitic infection transmitted by freshwater snails releasing schistosoma larvae in freshwater streams, rivers or lakes. The larvae can penetrate intact skin and cause infecton. There is no risk in sea water or chlorinated swimming pools. Most cases of schistosomiasis originate from Africa, although it is prevalent in many tropical areas.
There is no vaccine to prevent schistosomiasis. Travellers should avoid wading, swimming or bathing in fresh waters in areas at risk.
Initial symptoms are an itchy papular rash, with other symptoms developing within two-to-three weeks. These include fever, urticaria, malaise, diarrhoea, cough, headaches, myalgia and weight loss, although some individuals remain symptomless. Suspected cases should be referred to a specialist in tropical medicines for treatment.