Schistosomiasis

Alternative names:

blood fluke; Katayama fever

Definition:

An infection caused by one of five species of the parasites Schistosoma.

Causes, incidence, and risk factors:

Schistosoma infections are contracted when humans are in contact with contaminated water. The parasite in its infective stages is called a cercariae and 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 specie is involved. Likely areas include the bladder, rectum, intestines, liver, portal venous system, spleen, or lungs.

Clinical presentation of schistosomiasis varies with the species of worm. 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).

Schistosomiasis caused by the five major species is not found in the United States. However it is prevalent in many tropical or subtropical areas around the world. Worldwide this is a common illness thought to affect more than 200 million people.