Schistosomiasis

Symptoms

• Cercarial dermatitis (swimmer's itch) — pruritic papular rash at penetration site within hours to days
• Katayama fever (acute schistosomiasis) 4-8 weeks after exposure: fever, urticaria, eosinophilia, hepatosplenomegaly, cough — coincides with egg laying
• Intestinal: chronic abdominal pain, intermittent diarrhea, blood in stool
• Hepatosplenic: hepatosplenomegaly with periportal fibrosis ('pipestem' or Symmers fibrosis), variceal bleeding, ascites
• Urogenital (S. haematobium): terminal hematuria, dysuria, hematospermia, infertility, bladder polyps and ulcers; long-term: squamous cell carcinoma of the bladder
• Female genital schistosomiasis: pelvic pain, contact bleeding, infertility, increased HIV acquisition risk
• Neuroschistosomiasis: transverse myelitis (S. mansoni/haematobium spinal cord involvement), seizures (S. japonicum cerebral)

Signs / physical exam

• Hepatosplenomegaly, ascites in advanced hepatic disease
• Stigmata of portal hypertension WITHOUT cirrhosis (preserved synthetic function early)
• Bladder tenderness, perineal mass
• Spinal cord findings (weakness, sensory level, bladder dysfunction) in spinal schistosomiasis
• Eosinophilia

Classic findings

Returned traveler or immigrant from sub-Saharan Africa with hematuria (S. haematobium) or hepatosplenomegaly and esophageal varices despite normal synthetic function (S. mansoni). Eosinophilia and characteristic eggs on urine or stool microscopy with the species-specific spine: lateral spine = S. mansoni, terminal spine = S. haematobium, no spine or tiny lateral knob = S. japonicum.

Diagnostic criteria

Identification of characteristic eggs in stool, urine, or biopsy is definitive. Serology supports diagnosis when eggs not recovered, especially in low-burden travelers and migrants.

Labs

• Stool ovum and parasite (S. mansoni, japonicum)
• Urine microscopy for eggs (S. haematobium) — best at midday, collected after exercise
• Schistosoma serology by ELISA — sensitive for screening in low-burden travelers
• Schistosoma PCR (where available)
• CBC: eosinophilia (acute phase prominent, chronic less so)
• LFTs, BMP
• Rectal or bladder biopsy if eggs not recovered but suspicion high
• CSF examination if neurologic symptoms

Imaging

• Abdominal ultrasound: periportal fibrosis ('pipestem'), portal hypertension, splenomegaly, bladder wall thickening, hydronephrosis
• CT/MRI to characterize hepatic, splenic, urinary findings
• Cystoscopy for bladder polyps, ulcers, malignancy
• Echo for pulmonary hypertension
• MRI spine in suspected neuroschistosomiasis

First-line

• Praziquantel 40 mg/kg PO single dose (S. mansoni, S. haematobium) or 60 mg/kg PO divided over one day (S. japonicum, S. mekongi)
• Repeat dose in 4-6 weeks may improve cure rates
• For acute schistosomiasis (Katayama fever): supportive care with corticosteroids to dampen inflammatory response; delay praziquantel until 6-12 weeks post-exposure to allow eggs to mature (praziquantel kills only adult worms, not migrating schistosomula) — exact timing varies and some centers treat earlier with steroid coverage
• Neuroschistosomiasis: praziquantel PLUS corticosteroids to reduce inflammation
• Mass drug administration in endemic areas under WHO programs

Second-line / adjunct

• Oxamniquine for S. mansoni in regions with availability (largely supplanted by praziquantel)
• Surveillance for bladder cancer in chronic S. haematobium
• Hepatic decompensation: management of portal hypertension including band ligation, beta-blockers; transplant in select cases
• HIV co-management is important; female genital schistosomiasis facilitates HIV transmission