A 38-year-old man was evaluated at the hospital because of postprandial abdominal pain. Six weeks earlier, a diarrheal illness had developed while he was working in Madagascar. Diagnosis?
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Now I have all the information needed. Pulling together the full clinical picture:
The diagnosis is Schistosomiasis (Schistosoma mansoni) - specifically the acute phase (Katayama syndrome) transitioning to intestinal/hepatic schistosomiasis.
This is a textbook case. Here is my full analysis:
Diagnosis: Schistosomiasis (Schistosoma mansoni)
Why this fits the case
| Feature | Clinical Significance |
|---|---|
| 38-year-old man | Non-immune traveler - highest risk for acute/subacute presentation |
| Working in Madagascar | Madagascar is a well-known endemic area for S. mansoni (sub-Saharan Africa) |
| Diarrheal illness 6 weeks ago | Matches the 4-8 week timeline of Katayama syndrome (acute schistosomiasis) - worms mature into adults and begin egg deposition, triggering serum sickness-like illness |
| Postprandial abdominal pain now | Classic feature of intestinal schistosomiasis from egg-induced inflammation of the intestinal/mesenteric venous plexus |
Pathophysiology
Infection occurs via skin penetration by cercariae shed from freshwater snails. S. mansoni cercariae penetrate skin during exposure to contaminated freshwater (lakes, rivers, streams - abundant in Madagascar). The larvae enter the bloodstream, migrate through the lungs, and mature into adult worms residing in the mesenteric venous plexus of the intestines.
- 4-8 weeks after exposure: females begin egg deposition - this triggers the acute immunologic response (Katayama syndrome): fever, malaise, diarrhea, abdominal pain, hepatosplenomegaly, eosinophilia
- Eggs trapped in intestinal submucosa and portal system cause granulomatous inflammation - leading to postprandial abdominal pain as intestinal blood flow is stressed with eating
- With higher worm burdens: hepatosplenomegaly, portal hypertension, ascites, varices
(Red Book 2021, p.1034; Sherris & Ryan's Medical Microbiology, p.1641)
Key Differential Diagnoses to exclude
- Amoebiasis (Entamoeba histolytica) - also endemic in Madagascar; presents with dysentery (bloody diarrhea), abdominal cramps, tenesmus. Diagnosis by stool antigen/PCR or colonoscopy biopsy. Treatment: metronidazole + paromomycin. Postprandial pain is less characteristic.
- Giardiasis (Giardia lamblia) - watery, fatty, foul-smelling diarrhea; cramping and bloating, but not specifically postprandial
- Tropical sprue - chronic diarrhea + malabsorption after residence in tropical areas; presents more insidiously over months; treated with tetracycline + folate. Note: tropical sprue is rare in Africa per Harrison's.
- Intestinal angina (chronic mesenteric ischemia) - postprandial pain is the hallmark, but this occurs in older patients with atherosclerotic disease, not in a 38-year-old traveler returning from Africa
Workup
- Stool microscopy for Schistosoma eggs (lateral spine = S. mansoni)
- Serology (ELISA for anti-schistosomal antibodies) - sensitive in non-immune travelers
- CBC: eosinophilia is characteristic
- Liver function tests, ultrasound of liver/spleen
- Stool PCR (gold standard if available)
Treatment
- Praziquantel 40 mg/kg/day in 2 divided doses for 1 day - drug of choice for S. mansoni
- In acute Katayama syndrome: corticosteroids may be added to control the immune response before/with praziquantel
- Follow-up stool exam at 1-2 months to confirm cure
(Red Book 2021; GOLDMAN-CECIL MEDICINE)
Bottom line: This is a classic presentation of acute/subacute intestinal schistosomiasis (S. mansoni) in a non-immune traveler to Madagascar. The 6-week timeline from diarrheal illness to postprandial abdominal pain perfectly matches the natural history of Katayama syndrome and early intestinal disease from egg deposition. Eosinophilia on CBC would strongly support this diagnosis.
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