Schistosomiasis is an infection caused by a parasite. The parasite lives on certain snails which live in fresh water, most commonly in tropical areas, especially in Africa. Water sports, swimming or showering in these waters should be avoided.


An itchy rash can appear on the skin, known as “swimmers itch”. Sometimes a fever can develop 2-6 weeks later, with diarrhoea, cough or other symptoms (“Katayama fever”). Long-term infection may have no symptoms for years.

How do you catch schistosomiasis?

The tiny parasitic worms in the water burrow through the skin. They then travel to the veins of the bladder or bowels and release eggs.

Incubation period

Usually 2-12 weeks for the initial infection.


Blood tests no earlier than 8 weeks after contact with the fresh water can confirm the diagnosis. St


Avoid water sports, swimming or wading in fresh water lakes and rivers in the tropics. If crossing a river cannot be avoided, wear waterproof footwear and try to find an area where the water is fast flowing.


A drug called praziquantel is used to treat schistosomiasis, but is not effective in the early stage of infection - so taking it after a swim is not likely to help. Any traveller who has been in fresh water in tropical areas should see their doctor 8-12 weeks later for tests.