Schistosomiasis

An infestation of flukes that can damage the liver and bladder

  • More common in children
  • Swimming in fresh water containing infested snails is a risk factor
  • Gender and genetics are not significant factors

People who bathe in lakes, canals, or unchlorinated freshwater pools in the tropics are at risk of schistosomiasis, also known as bilharzia. The disease is caused by any of five species of fluke (types of flatworm) of the schistosoma group. Freshwater snails release larvae (immature forms) of the parasite, which can penetrate the skin of bathers. Once inside the body, the parasites mature into adults, and the females lay eggs, which may cause inflammation. Schistosomiasis affects about 200 million people worldwide, mainly in developing countries. People in the UK become infested only when visiting tropical regions.

What are the symptoms?

The symptoms of schistosomiasis vary depending on the species of fluke. Most people experience itching (known as “swimmer’s itch”) at the site where the parasite has entered the skin. The itching usually occurs within a day of exposure to the parasite. Some people may have no further symptoms, whereas others may develop them within 4–6 weeks. Symptoms may include:

  • Fever.

  • Muscle pains.

  • Diarrhoea.

  • Coughing and vomiting.

  • Passing urine more frequently, with a burning sensation.

  • Blood in the urine, especially at the end of the stream.

Without treatment, schistosomiasis may damage the liver or the urinary system. In many cases, this damage is life-threatening. A long-standing, untreated infestation may cause liver cirrhosis, bladder tumours, and kidney failure.

Schistosomiasis flukes

The adults of the flukes that cause schistosomiasis live in pairs. The female fluke lives in a groove in the male’s body.

What might be done?

Schistosomiasis is usually diagnosed by finding fluke eggs in a sample of either urine or faeces. Sometimes, the condition is diagnosed by a rectal biopsy, in which a sample of tissue is taken from the rectum and examined under a microscope for eggs. The biopsy is usually accompanied by a blood test to look for antibodies that the body produces against the parasite. In nearly all cases, the infestation is treated with an anthelmintic drug, which usually is effective in killing the worms. Schistosomiasis can be prevented by not swimming or wading in fresh water in the regions of the world where the infestation is known to occur.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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