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a genus of trematodes, including several species parasitic in the blood of humans and domestic animals. The organisms are called schistosomes or blood flukes. Larvae (cercariae) enter the body of the host by way of the digestive tract, or through the skin from contact with contaminated water, and migrate in the blood to small blood vessels of organs of the intestinal or urinary tract; they attach themselves to the blood vessel walls and mature and reproduce. The intermediate hosts are snails of various species.
Schistosoma haemato´bium a species endemic in North, Central, and West Africa and the Middle East; the organisms are found in the venules of the urinary bladder wall, and eggs may be isolated from the urine.
Schistosoma japo´nicum a species geographically confined to China, Japan, and nearby countries; found chiefly in the venules of the intestine.
Schistosoma manso´ni a species widely distributed in Africa and parts of South America; the organisms are found in the host's mesenteric veins, and eggs may be found in the feces.
the Oriental or Japanese blood fluke, a species having eggs with small lateral spines, usually only a small knob; causes schistosomiasis japonica, with extensive pathology from encapsulation of the eggs, particularly in the liver, and is the most pathogenic of the three common schistosome species afflicting humans, possibly owing to greater egg production per female worm; it is also the most intractable to treatment and the most difficult to control, as the intermediate hosts are amphibious snails (species of Oncomelania, family Hydrobiidae) that can leave the water to avoid molluscicides, and also because many other animals, such as pigs, oxen, cattle, and dogs, serve as reservoir hosts.
Schis·to·so·ma ja·po·ni·cum(skis'tō-sō'mă ja-pon'ik-ŭm)
The Asian or Japanese blood fluke, a species that causes schistosomiasis japonica, with extensive pathology from encapsulation of the eggs, particularly in the liver. The intermediate hosts are amphibious snails; other animals, such as pigs, oxen, cattle, and dogs, serve as reservoir hosts.
A species common in many parts of Asia. Adults live principally in branches of the superior mesenteric vein. Eggs work their way through the intestinal wall of the host into the lumen and are discharged with feces. Oriental schistosomiasis is caused by this species.
See also: Schistosoma