Schistosomiasis is caused by infection with Schistosoma haematobium, S. mansoni, S. japonicum, S. mekongi, or S. intercalatum. The various species are associated with different clinical complications. The clinical features also differ in acute and chronic infections.
The diagnosis of schistosomiasis will be reviewed here. The epidemiology, pathogenesis, clinical features, treatment, and prevention of these infections are discussed separately. (See "Epidemiology, pathogenesis, and clinical features of schistosomiasis" and "Treatment and prevention of schistosomiasis".)
Many people who are infected with schistosomiasis are asymptomatic and only investigated because infection is suspected on the basis of epidemiologic history (eg, travelers). (See "Epidemiology, pathogenesis, and clinical features of schistosomiasis".)
Routine blood or urine tests may show nonspecific abnormalities. The diagnosis of schistosomiasis can be confirmed by microscopy with egg identification, by serology, or by consistent radiologic findings in the appropriate clinical scenario. A diagnosis of schistosomiasis should prompt initiation of treatment, even if the patient is asymptomatic, since adult worms can live for years . (See "Treatment and prevention of schistosomiasis".)
Nonspecific laboratory abnormalities — A routine full blood count may show eosinophilia in infected patients . The degree of eosinophilia relates to the stage, intensity, and duration of infection, as well as to genetic determinants of the host . Most studies suggest between one- and two-thirds of infected patients have a peripheral eosinophilia, which is frequently most marked early in the course of infection. Eosinophilia is also a frequent finding in patients with Katayama fever, a hypersensitivity reaction seen with acute infection . (See "Epidemiology, pathogenesis, and clinical features of schistosomiasis", section on 'Acute infection'.)