Schistosoma is a trematode, or blood-fluke. This is a parasitic flatworm.
Snails are the host for this parasite, and humans can develop infection from being exposed to snail-infested waters.
The symptoms of schistosomiasis occur after an intense immune response from the body to this parasite. Immune reaction to worms and trapped eggs lead to cellular infiltrant, leading to granulomas, inflammation and fibrosis.
As eggs pass through the digestive system, many pathologic events can take place. Ulceration can occur, eggs can become lodged in the intestines, and worms can become trapped in intestinal mesenteric veins.
Typically, these parasites migrate to the liver sinusoids, where they feed on red blood cells. From this liver migration, hepatorenal blood flow can become interrupted (through obstruction via worm or egg), leading to hepatosplenic dysfunction and granuloma formation. Schistisoma mansoni and japonicum are specifically known for leading to hepatic granuloma formation.
Some types of schistosoma can migrate to ureteral areas or to the bladder and kidneys. These can lead to urinary granulomas and genitourinal issues in patients. Most importantly, Schistosoma hematobium can lead to squamous cell carcinoma of the bladder in those who are chronically infected. Patients display painless hematuria.
The most common diagnostic technique involves detection of parasitic antigens by ELISA, where the patient's blood is sampled.
Praziquantel, a powerful antihelminthic medication is effective against flukes, like schistosomiasis.
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