Synopsis
Recognise acute and chronic schistosomiasis after freshwater exposure, choose time- and species-appropriate tests, treat mature infection safely, and identify neurological, portal and urogenital complications.
- Schistosome cercariae penetrate intact skin during contact with contaminated freshwater containing infected snails; properly chlorinated pools and seawater do not transmit infection.
- An itchy cercarial rash can occur within days, while Katayama fever with urticaria, cough, diarrhoea and eosinophilia usually appears weeks later during early egg production.
- S. haematobium causes urogenital disease with terminal haematuria, bladder and ureteric fibrosis and squamous-cell bladder-cancer risk; S. mansoni and S. japonicum cause intestinal and hepatosplenic disease.
- First-line assessment combines a precise freshwater history, FBC with eosinophils, schistosome serology and targeted urine or stool microscopy after sufficient time for maturation.
- Definitive parasitological evidence is characteristic eggs in urine, stool or tissue, but low-burden traveller infection often requires serology and repeated concentrated specimens.
- Collect S. haematobium urine near midday, ideally terminal urine after activity; collect multiple stool samples for intestinal species because egg excretion varies.
- Praziquantel is the treatment of choice for mature worms: commonly 40 mg/kg orally in two divided doses during one day for S. haematobium or S. mansoni.
- For S. japonicum or S. mekongi, specialists may use a 60 mg/kg total oral dose in two or three divided doses over one day; species and local protocol must be confirmed.
- Praziquantel has limited activity against immature worms, so very early treatment can fail and repeat therapy after maturation may be required.
- Prevention is avoidance of untreated freshwater in endemic areas; there is no licensed vaccine or dependable pre-exposure tablet for travellers.
Key red flags
Acute weakness, saddle sensory change, urinary retention or incontinence after endemic freshwater contact requires emergency spinal imaging and specialist treatment.
Seizure, focal neurological deficit, severe headache or altered consciousness may represent cerebral schistosomiasis and needs urgent neuroimaging.
Fever, urticaria, cough, diarrhoea and marked eosinophilia several weeks after a heavy first exposure suggests acute Katayama syndrome, which can worsen around treatment.
Haematemesis, melaena, splenomegaly or thrombocytopenia can indicate portal hypertension from chronic hepatosplenic disease despite preserved hepatocyte function.
Visible haematuria, obstructive uropathy, hydronephrosis or a bladder lesion requires urological evaluation because chronic urinary schistosomiasis causes fibrosis and cancer risk.
A negative early serology or single urine or stool microscopy does not exclude infection; testing sensitivity depends on timing, burden, species and specimen collection.
Fever, chills, urticaria, cough, myalgia, abdominal pain or diarrhoea with eosinophilia several weeks after first heavy exposure reflects systemic immune-complex disease.
Investigation priorities
Establish whether schistosomiasis is plausible and identify systemic or organ injury.
Management branches
A traveller or migrant reports skin contact with untreated freshwater in a schistosomiasis-risk region.
- Record the country, water body, exposure date and duration, then ask about rash, fever, cough, bowel, urinary, genital and neurological symptoms.
- Request FBC with eosinophils and plan serology after the appropriate post-exposure interval; symptomatic or eosinophilic patients need earlier specialist assessment.
- Add repeated targeted urine or stool microscopy when maturation time, species geography and symptoms make egg excretion plausible.
- Investigate organ symptoms directly rather than assuming that a future serology result will explain haematuria, bleeding, neurological deficit or portal signs.