Classification: ICD-9 120; ICD-10 B65
Synonyms: Bilharziasis, snail fever, Katayama fever or syndrome, intestinal schistosomiasis.
Agent: Trematode worms Schistosoma japonicum, S. malayensis, and S. mekongi.
Reservoir: Humans, dogs, cats, pigs, cattle, water buffalo and wild rodents for S. japonicum, rodents for S. malayensis, pigs and dogs for S. mekongi.
Vector: Freshwater snails: Oncomelania spp. for S. japonicum, Robertsiella spp. for S. malayensis, Neotricula spp. for S. mekongi.
Transmission: Contact with freshwater bodies containing cercariae that penetrate skin or mucous membranes; drinking contaminated water (less common).
Cycle: Snail–human–snail. Infected humans shed eggs into the water, which hatch into larvae (miracidia) that enter snails and develop into motile larvae (cercariae). The cercariae are shed into the water and penetrate the skin of humans with water contact. Cercariae enter the bloodstream and settle in the liver, where they grow into adult male and female worms that migrate to the abdominal veins, mate, and produce eggs. Snails are infectious for up to 3 months, humans for 10 years or more.
Incubation period
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