Bathing in tropical inland waters
Updated on All content is checked by medical journalists.After a day of trekking or a tour, many a tropical lake or river beckon for a swim. Sometimes a special kind of danger lurks here, namely pair leeches, worm-like parasites that dig into the skin of bathers and lead to schistosomiasis. After malaria, schistosomiasis is the most common parasitic disease in humans in the tropics.
It only occurs in areas that are home to a certain species of water snail, which the parasites need to develop. The snail can be found on the embankments of standing or slowly flowing fresh water. Distribution areas are mainly Africa, the east of Central and South America and a few areas in Asia.
The pathogens penetrate through the skin on contact with contaminated fresh water, i.e. when bathing, washing, wading through a stream or fishing. The larvae are also ingested by drinking contaminated water. Six to 48 hours after the parasites enter, a rash with severe itching occurs. Chills, fever, cough and headache follow after two weeks. If left untreated, the leeches infect the intestines and bladder and cause permanent discomfort. Schistosomiasis heals without any problems, as long as it is treated in good time with the anti-worm agent praziquantel.
In summary, the most important tips:
- Inquire before departure and again on site whether schistosomiasis is common in your holiday area.
- There is a particular risk of infection when bathing in stagnant waters with embankments, not at stony waterfalls in the mountains.
- The pair of leeches only reproduce in fresh water.
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