Schistosomiasis

Swimmer's itch

Antibodies

Schistosomiasis

Definition:

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

Alternative Names:

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

Causes, incidence, and risk factors:

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:

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:

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:

Praziquantel
With acute infection, corticosteroids may be given

Expectations (prognosis):

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

Complications:

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:

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:

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

Review Date: 8/14/2002
Reviewed By: Donna R. Cooper, MD, MPH. Department of Medicine, Massachusetts General Hospital, Boston, MA. Review provided by VeriMed Healthcare Network.

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