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For further information, see CMDT Part 35-13: Schistosomiasis (Bilharziasis)

Key Features

Essentials of Diagnosis

  • History of freshwater exposure in an endemic area

  • Acute schistosomiasis: fever, headache, myalgias, cough, urticaria, diarrhea, and eosinophilia

  • Intestinal schistosomiasis: abdominal pain, diarrhea, and hepatomegaly, progressing to anorexia, weight loss, and features of portal hypertension

  • Urinary schistosomiasis: hematuria and dysuria, progressing to hydronephrosis and urinary infections

  • Diagnosis: characteristic eggs in feces or urine; biopsy of rectal or bladder mucosa; positive serology

General Considerations

  • Intestinal schistosomiasis, with infection of mesenteric venules, caused by

    • Schistosoma mansoni, which is present in Africa, the Arabian peninsula, South America, and the Caribbean

    • Schistosoma japonicum, which is endemic in China and Southeast Asia

    • Schistosoma mekongi, which is endemic near the Mekong River in Southeast Asia

    • Schistosoma intercalatum and Schistosoma guineensis, which occur in parts of Africa

  • Urinary schistosomiasis, with infection of venules of the urinary tract

    • Caused by Schistosoma haematobium

    • Endemic in Africa and the Middle East

  • Transmission is focal, with greatest prevalence in poor rural areas

  • Humans are infected with schistosomes after contact with freshwater containing cercariae released by infected snails

  • Chronic infection can result in scarring of mesenteric or vesicular blood vessels, leading to portal hypertension and alterations in the urinary tract

  • Acute schistosomiasis

    • May occur in previously uninfected individuals

    • Febrile illness develops 2–8 weeks after infection


  • Affects more than 200 million persons worldwide, leads to severe consequences in 20 million persons and about 100,000 deaths annually

  • Prevalence of infection and illness typically peaks at about 15–20 years of age

Clinical Findings

  • Cercarial dermatitis

    • Localized erythema develops in some individuals, which can progress to a pruritic maculopapular rash that persists for some days

    • Dermatitis can be caused by human schistosomes and, in nontropical areas, by bird schistosomes that cannot complete their life cycle in humans (swimmer's itch)

  • Acute schistosomiasis (Katayama syndrome)

    • A febrile illness may develop 2–8 weeks after exposure in persons without prior infection, most commonly after heavy infection with S mansoni or S japonicum

    • Presenting symptoms and signs include

      • Acute onset of fever

      • Headache

      • Myalgias

      • Cough

      • Malaise

      • Urticaria

      • Diarrhea, which may be bloody

      • Hepatosplenomegaly

      • Lymphadenopathy

      • Pulmonary infiltrates

    • Localized lesions may occasionally cause severe manifestations, including CNS abnormalities and death

  • Chronic schistosomiasis

    • Many infected persons have light infections and are asymptomatic

    • However, an estimated 50–60% of patients have symptoms and 5–10% have advanced organ damage

    • Asymptomatic infected children may suffer from anemia and growth retardation

    • Intestinal schistosomiasis

      • Symptomatic patients typically experience abdominal pain, fatigue, diarrhea, and hepatomegaly

      • Over years, anorexia, weight loss, weakness, colonic polyps, and features of portal hypertension develop

      • Late manifestations include hematemesis from esophageal varices, hepatic failure, and pulmonary hypertension

    • Urinary schistosomiasis

      • May present within months of infection with hematuria and dysuria, most commonly in children and young adults

      • Fibrotic changes ...

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