Schistosomiasis

Background

• Caused by parasitic trematodes of the species Schistosoma
• Reservoir is freshwater snails
• Endemic in areas of Africa and Southern Asia
• The Cercariae (the stage of trematode released by the snail) can infect by direct penetration through the skin
• Infects >200million people worldwide with 10% suffering severe consequences

Clinical Features

Acute

• Cutaneous rash/pruritus from cercariae penetration (immediate)
• Katayama fever
  • Fever, abdominal pain, fatigue, cough, diarrhea, eosinophilia
  • Lasts 4-8 weeks

Chronic (mostly a chronic condition)

• Second most common cause of esophageal varices worldwide
• Greatly elevated bladder cancer rates in endemic areas
• Can cause renal failure, liver failure, pulmonary hypertension, GI bleeds and rarely CNS symptoms
  • Mostly through fibrosis of affected organs
• Genitourinary schistosomiasis
  • Caused by sores in the genital tract
  • May persist even after treatment
  • Greatly increases risk of HIV infection

Differential Diagnosis

• UTI
• STD
• Intestinal parasites
• Traveler's diarrhea

Evaluation

Calcifications on bladder wall caused by urinary schistosomiasis

CT of hepatosplenic S. mansoni infection illustrating irregular liver surface and periportal fibrosis and enhancement of portal venous structures surrounded by inner ring of hypoattenuation and outer ring of enhancement (arrows). Hypoattenuated ring presumably represents areas of periportal fibrosis with decreased vascularity, whereas enhancing rim may be due to periportal inflammation. These concentric rings correspond to the “bull's eye” appearance of periportal fibrosis previously described with ultrasound.

Work-up

• ELISA
• PCR from stool or urine
• Stool and Urine for ova/parasites
  • biopsy may be needed for those who do not show ova/parasites in stool/urine
• CBC, LFTs, BMP, blood cultures
• Consider ultrasound for hepatosplenic (periportal fibrosis) or urinary disease (hydro)
• Echocardiography and CXR for pulmonary hypertension and/or cor pulmonale
• Consider CT or MRI for CNS disease or further workup of periportal fibrosis

Management

• Praziquantel 20mg/kg PO for two doses in 1 day
  • S.japnonicum requires 3 doses in 1 day

Disposition

• Generally may be discharged
• Admit if concern for CNS infection

See Also

• Parasitic infection