Microbiology · Year 2 · from Microbiology
Case 3: Schistosomiasis with Portal Hypertension
Presentation
A 45-year-old man from Egypt presents with progressive abdominal distension and fatigue over 6 months. He immigrated 15 years ago and recalls swimming in the Nile River as a child. Examination reveals splenomegaly, ascites, and dilated veins visible on the abdominal wall (caput medusae). There is no jaundice or hepatic encephalopathy. Liver function tests show mildly elevated alkaline phosphatase but normal bilirubin and transaminases. Ultrasound shows periportal fibrosis with a characteristic "clay pipe stem" pattern and moderate ascites. Stool examination reveals eggs with a prominent lateral spine.
Clinical Image
Stool microscopy showing Schistosoma mansoni egg with characteristic lateral spine, diagnostic of intestinal schistosomiasis.
Image Source: Lecture image - Schistosoma egg morphology
Questions
- What is the diagnosis, and which species is responsible?
- How did this patient acquire the infection, and what is the life cycle?
- Explain the pathophysiology of portal hypertension in this disease.
- What is the treatment approach?
Answers
- Diagnosis and species: This is hepatosplenic schistosomiasis with portal hypertension caused by Schistosoma mansoni (identified by the lateral-spined egg). S. mansoni is the species found in Africa, the Middle East, and South America. The clinical picture of portal hypertension with preserved hepatic synthetic function (normal bilirubin, no encephalopathy) is characteristic of "pipestem fibrosis."
- Life cycle and transmission:
- Cercariae (free-swimming larvae) released from freshwater snails penetrate human skin during water contact (swimming, bathing, farming)
- Larvae migrate through lungs to liver, maturing into adult worms
- Adult worms live in mesenteric venules (S. mansoni, S. japonicum) or bladder venous plexus (S. haematobium)
- Female worms release eggs; eggs must penetrate vessel wall and intestinal/bladder mucosa for excretion
- Eggs trapped in tissues cause the inflammatory response and pathology
- Eggs in stool/urine reach freshwater, hatch, infect snails, and the cycle continues
- Pathophysiology of portal hypertension: Unlike cirrhosis, schistosomal liver disease is caused by:
- Egg embolization: Eggs carried by portal blood lodge in portal venules within the liver
- Granulomatous inflammation: Immune response to eggs causes granuloma formation around each egg
- Periportal fibrosis ("Symmers' pipestem fibrosis"): Progressive fibrosis around portal tracts, NOT diffuse parenchymal cirrhosis
- Portal vein obstruction: Fibrosis obstructs portal blood flow
- This is presinusoidal portal hypertension, so hepatocyte function is preserved (normal synthetic function, no encephalopathy)
- Splenomegaly results from portal congestion
- Treatment:
- Antiparasitic therapy: Praziquantel 40 mg/kg in divided doses (single day treatment); kills adult worms; should be given even in chronic disease to prevent ongoing egg production
- Portal hypertension management:
- Beta-blockers for variceal prophylaxis
- Endoscopic band ligation for varices
- Diuretics for ascites
- TIPS or surgical shunts in refractory cases
- Prognosis: Unlike cirrhosis, hepatic function may be preserved for years; treatment can halt progression
- Screening: Travelers and immigrants from endemic areas with eosinophilia or liver disease should be tested