MedlinePlus Medical Encyclopedia: Schistosomiasis

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Schistosomiasis

Contents of this page:
Illustrations Alternative names Definition Causes, incidence, and risk factors Symptoms Signs and tests	Treatment Expectations (prognosis) Complications Calling your health care provider Prevention

Illustrations

Swimmer's itch

Antibodies

Alternative names Return to top

Bilharzia; Katayama fever; Swimmer's itch; Blood fluke

Definition Return to top

Schistosomiasis is an infection caused by one of the five species of the parasite, Schistosoma.

Causes, incidence, and risk factors Return to top

Schistosoma infections are contracted through contact with contaminated water. The parasite in its infective stages is called a cercaria. It swims freely in open bodies of water.

On contact with humans, the parasite burrows into the skin, matures into another larval stage (schistosomula), then migrates to the lungs and liver (where it matures into the adult form).

The adult worm then migrates to the anatomic area of its preference, depending on which species is involved. Likely areas include the bladder, rectum, intestines, liver, portal venous system, spleen, and lungs.

Schistosomiasis is not usually found in the United States. However, it is prevalent in many tropical or subtropical areas, and it is a common illness thought to affect more than 200 million people.

Symptoms Return to top

Symptoms vary with the species of worm and the phase of infection.
Initial invasion of the skin may cause itching and a rash (swimmer's itch).
Heavy infestation may cause fever, chills, lymph node enlargement, and liver and spleen enlargement.
Urinary symptoms may include frequency, painful urination (dysuria), and blood in urine (hematuria).
Intestinal symptoms include abdominal pain and diarrhea (which may be bloody).

Signs and tests Return to top

Test for schistosome eggs in urine
Test for schistosome eggs in stool
Biopsy of tissue suspected of having infection
Anemia
High eosinophil count in blood
Low platelets
Urinalysis
Antibody test

Treatment Return to top

Praziquantel
With acute infection, corticosteroids may be given

Expectations (prognosis) Return to top

Treatment before significant damage or severe complications usually produces good results.

Complications Return to top

Kidney and bladder obstruction
Chronic renal failure
Bladder cancer
Chronic liver damage with an enlarged spleen
Colon inflammation with bloody diarrhea
Pulmonary hypertension
Right-sided heart failure
Seizures
Recurrent blood infections can occur because bacteria can enter the bloodstream via the colon if it has become irritated

Calling your health care provider Return to top

Call your health care provider if you have traveled to an area where the disease is known to exist, have had exposure to contaminated or suspect bodies of water, or have developed symptoms suggestive of schistosomiasis.

Prevention Return to top

Avoid swimming or bathing in water known to be contaminated or potentially contaminated
Avoid bodies of water of unknown safety
Eradication of snails (an intermediate host for the parasite) in areas used by humans

Update Date: 7/16/2004

Updated by: Daniel Levy, M.D., Ph.D., Infectious Diseases, Greater Baltimore Medical Center, Baltimore, MD. Review provided by VeriMed Healthcare Network.

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