Schistosomiasis
Schistosomiasis is a trematode infection acquired by cercarial penetration of skin during freshwater contact, causing intestinal and hepatosplenic disease with Schistosoma mansoni or S. japonicum, or urinary tract disease with S. haematobium. Diagnosis rests on demonstrating eggs in stool or urine or a positive serology, and praziquantel is the treatment for every species.
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What this article covers
- Overview
A freshwater-acquired trematode infection with two clinically distinct patterns: Schistosoma mansoni and Schistosoma japonicum cause intestinal and hepatosplenic disease with portal hypertension…
- Epidemiology
Endemic to unindustrialized tropical regions with freshwater exposure: infection is far more common overall in these settings than in industrialized countries, tracking direct contact with…
- Risk factors
Direct skin contact with contaminated freshwater: swimming, wading, bathing, or working in lakes, rivers, or irrigation canals in an endemic area is the dominant risk factor, because cercariae penetrate intact skin on contact.
- Pathophysiology
Cercarial skin penetration: free-swimming cercariae released from infected freshwater snails penetrate intact human skin on contact with contaminated water, entering the bloodstream.
- Clinical features
Painless hematuria, the hallmark of S. haematobium disease: chronic urinary tract infection classically presents with painless hematuria, reflecting bladder wall egg deposition and later squamous cell carcinoma risk.
- Differential diagnosis
Urothelial (transitional cell) bladder carcinoma: shares painless hematuria with S.
- Diagnosis
The diagnosis is confirmed by identifying Schistosoma eggs in stool or urine, or by serology when eggs are not found: stool microscopy identifies S.
- Management
First, treat every confirmed infection with praziquantel, dosed by the infecting species and given as a single day's course.
- Complications
Squamous cell carcinoma of the bladder: the most serious long-term complication of chronic S.
- Prognosis
Curable with a single course of praziquantel in most patients, particularly when treated before advanced fibrosis or malignant transformation develops.
- Prevention
Avoid contact with freshwater known or suspected to be contaminated in endemic regions (lakes, rivers, and irrigation canals in Africa, the Middle East, South America, and East Asia), since cercariae…
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