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Disease information

Schistosomiasis

Schistosomiasis, also called bilharzia, is an infection caused by parasitic worms. Larvae in contaminated freshwater enter through the skin. Some people have no symptoms, but untreated infection can persist for years. Parasite eggs can cause inflammation and damage to the intestines, liver, or urinary tract, depending on the species.

Prevention: Behavior

Symptoms

  • An itchy rash after water exposure
  • Later fever, headache, muscle aches, cough, or diarrhea
  • Blood in the urine or stool in some infections
  • Sometimes no noticeable symptoms

Transmission

  • Skin contact with contaminated freshwater while swimming, bathing, or wading; swallowing water is not necessary

Prevention

Avoid contact with freshwater in areas where schistosomiasis occurs. Clear or fast-flowing water can still carry the parasite. Saltwater does not transmit human schistosomiasis, and adequately chlorinated pools are safer alternatives. Towel drying or insect repellent cannot reliably prevent infection.

Where it occurs

Most cases occur in Africa, with additional areas of transmission in parts of Asia and South America.

Diagnosis and care

Tell a healthcare professional about freshwater exposure, even if you feel well. Tests can look for infection, and antiparasitic treatment is available.

Source

  • Schistosomiasis

    Based on CDC information

    Source language: English

    Source reviewed: April 23, 2025

    Source accessed: May 17, 2026

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