Schistosomiasis (also known as Bilharzia) is a parasitic infection, caused by Schistosoma worms. Infection occurs through direct contact with contaminated fresh water where certain snails may harbour the infection. Larval forms of the worm are released from these snails into fresh water and may penetrate human skin and migrate to internal organs.
Although schistosomiasis is found throughout tropical regions, in travellers it is most often acquired in Africa. Common travel destinations where schistosomiasis occurs include Malawi (particularly from Lake Malawi), Egypt, Kenya, Tanzania, South Africa and some areas of Brazil. Country-specific information on the risk of schistosomiasis can be found in our Country Information pages.
Travellers are at risk if they wade, swim or have other contact with fresh water from lakes or rivers in areas where schistosomiasis is common. Chlorination kills the parasite; therefore there should be no risk in well maintained swimming pools. Schistosomiasis cannot be contracted through sea water contact. Infection may cause no symptoms, but early symptoms can include a rash and itchy skin (‘swimmer’s itch’), fever, chills, cough, or muscle aches. If not treated, it can cause serious long term health problems such as intestinal or bladder disease.
There is currently no vaccine against schistosomiasis and no drug available to prevent infection. Where possible travellers should avoid contact with fresh water rivers and lakes in risk areas. This includes popular destinations such as Lake Malawi. Topical application of insect repellent before exposure to water or towel drying after accidental exposure to schistosomiasis are not reliable in preventing infection.
Schistosomiasis in travellers commonly occurs without symptoms. Those who have been swimming or bathing in fresh water in areas where the disease is common should be advised to undergo screening, ideally by an infectious diseases specialist.