Schistosoma

What is the relevance of Schistosoma for disease? Helminthes of the genus Schistosoma are the cause of schistosomiasis, originally termed bilharzia in honor of Theodor Bilharz, who first described these worm parasites in 1851. Aside from malaria, schistosomiasis is the most prevalent parasitic infection in the world, affecting over 200 million people in 76 countries of the tropics and subtropics. The blood flukes live in the abdominal veins of their vertebrate definitive hosts and produce eggs. About 50% pass through the intestinal wall to enter the gut lumen. Eggs retained in the gut wall induce inflammation, hyperplasia, ulceration, microabscess formation and polyposis. The remaining 50% are mainly deposited in spleen and liver resulting in presinusoidal inflammation and periportal fibrosis.