Cercarial dermatitis (swimmer's itch, schistosome larvae)
Overview
- Causative agent: Schistosoma haematobium (Urogenital Schistosomiasis), S. mansoni / S. japonicum (Intestinal Schistosomiasis).
- Transmission: Freshwater contact in endemic areas (Sub-Saharan Africa, Brazil, Middle East, Asia) — penetration of cercariae through the skin.
- Clinical presentation:
- Early phase: Cercarial dermatitis (itchy papules at the entry site) — "Swimmer's itch"
- Subacute: Katayama fever (fever, eosinophilia, hepatosplenomegaly, urticaria) 4–8 weeks after exposure
- Chronic: granulomatous reaction + fibrosis in liver/intestine/bladder; S. haematobium → hematuria + bladder cancer risk
- Diagnosis: Gold standard is egg detection in urine/stool plus serology and skin biopsy.
Differential diagnoses
- Cutaneous larva migrans
- Urticaria
- Filariasis
- Scabies
- Allergic contact dermatitis
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Note: This page is intended for medical education and does not replace diagnosis or treatment decisions in individual cases. Treatment and follow-up content is available in the app.