Epidemiology

• Occurrence: mainly rural areas with freshwater sources and poor sanitation

Etiology

Pathophysiology

Clinical features

1. Local reaction (swimmer's itch or cercarial dermatitis): pruritic maculopapular rash at the point of entry of cercaria into human skin
2. Acute schistosomiasis syndrome (Katayama fever)
   • Serum sickness-like disease: immune complex formation of antigens released from eggs and/or adult worms with host antibodies
   • Incubation period: 3–8 weeks
   • Clinical features: fever, fatigue, cough
3. Chronic schistosomiasis: Deposition of eggs leads to chronic inflammation and granuloma formation.

Subtypes

• Genitourinary schistosomiasis
  • S. haematobium
  • Hematuria, dysuria
  • Complications (especially with chronic infection)
    • Squamous cell carcinoma of the bladder (may cause painless hematuria)
      • Rare tumor (approximately only 2% of bladder malignancies are squamous cell carcinomas)
• Hepatosplenic schistosomiasis
  • Children and adolescents: hepatosplenomegaly
  • Adults with chronic infection: periportal fibrosis and portal hypertension
• Pulmonary schistosomiasis
  • All three pathogens
  • Pulmonary hypertension and cor pulmonale

Diagnostics

• Microscopic examination of stool or urine for eggs
  • S. mansoni: Eggs have a prominent lateral spine.
  • S. haematobium: Eggs have a prominent terminal spine.
  • S. japonicum: Eggs have a miniscule lateral spine.

Treatment

• Acute schistosomiasis syndrome
  • Administer glucocorticoids to reduce inflammation.
  • Administer praziquantel once inflammation improves.
• Chronic schistosomiasis: Administer praziquantel.