The short answer
Schistosoma haematobium is a parasite caught from contaminated fresh water. Long-term infection is linked to bladder cancer, mainly in parts of Africa and the Middle East. Avoiding infected water and treatment prevent it.
Schistosoma haematobium is classified as a known human carcinogen (IARC Group 1).
People are mainly exposed by skin contact with parasite-contaminated fresh water.
It is most strongly linked to bladder cancer.
A carcinogen classification describes hazard — whether something can cause cancer — not your personal risk at a given exposure.
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The simple version
This page is for travelers, people from affected regions, and their families. It explains how one parasite infection is linked to bladder cancer.
Schistosoma haematobium is a parasitic worm. It lives in some fresh waters in Africa and the Middle East. People get infected when the parasite enters the skin during swimming or wading. Over years, it can inflame the bladder and lead to bladder cancer.
What Schistosoma haematobium is
Schistosoma haematobium causes urinary schistosomiasis, also called bilharzia. The larvae live in freshwater snails. From there they pass through human skin in contaminated water. Long-term infection keeps the bladder inflamed. That chronic inflammation is classed as carcinogenic to humans.
How people are exposed
Common ways people come into contact with it:
- Contact with contaminated fresh water, such as swimming, wading, farming, or washing.
- Living in or traveling to endemic regions (places where the parasite is common) in Africa and the Middle East.
Repeated or long-term infection raises risk.
The cancer connection
Long-term Schistosoma haematobium infection is linked to bladder cancer, often a squamous-cell type.
The International Agency for Research on Cancer (IARC) grades cancer evidence on behalf of the World Health Organization. It places Schistosoma haematobium in Group 1, carcinogenic to humans. That is the strongest evidence category. It means the evidence is sufficient that this parasite can cause cancer in people.
Hazard is not the same as risk
Hazard and risk are easy to confuse, and they answer different questions. Calling this parasite a carcinogen is a statement about hazard. It says the parasite can cause cancer under some conditions. It does not describe your personal risk. That depends on whether you are exposed at all, how often, for how long, and other factors. One person never enters fresh water in an endemic area. Another farms in it daily. Their risks are not remotely the same, even though the parasite carries one label.
How to lower your exposure
- Staying out of fresh water for swimming or wading in endemic areas.
- Treating infection with medication (praziquantel). Ask a doctor about testing if you may have been exposed.
- Support clean-water and snail-control public health programs.
Bladder cancer risk also responds to other choices you make. To see where schistosomiasis sits among all the things that affect cancer risk, read our overview of cancer prevention and what raises cancer risk.
The bottom line
Schistosoma haematobium is a known human carcinogen (IARC Group 1). The useful step is knowing which waters carry the parasite and staying out of them where you can. If you have spent time in fresh water in those regions, mention it to your doctor.
Common questions
Does schistosoma haematobium cause cancer?
Yes. Schistosoma haematobium is classified as a known human carcinogen, which means there is strong evidence it can cause cancer in people. How much any one person's risk rises depends on how much they are exposed to and for how long.
How are people exposed to schistosoma haematobium?
Most exposure happens by skin contact with parasite-contaminated fresh water.
Which cancers are linked to schistosoma haematobium?
It is most strongly linked to bladder cancer.
How can I reduce my exposure to schistosoma haematobium?
The main steps are avoiding contaminated fresh water and treating infection.
Does a carcinogen label mean I will get cancer?
No. A classification is about hazard — whether schistosoma haematobium can cause cancer under some conditions — not a prediction that any one exposed person will develop cancer. Your actual risk depends on the amount and length of exposure and other factors.
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Last updated: 2026-08-10Next planned review: 2028-07-05
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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