Katayama syndrome — DTM&H MCQ

Correct answer: B — Acute schistosomiasis syndrome

The correct answer is B, acute schistosomiasis syndrome (Katayama syndrome). This presentation, fever, dry cough, urticarial rash and marked eosinophilia occurring several weeks after freshwater exposure in sub-Saharan Africa, is the classic immune-complex hypersensitivity reaction to migrating schistosomulae and early egg deposition, which typically occurs 3 to 12 weeks after primary infection, well before eggs are reliably detectable in stool or urine. Negative stool and urine microscopy at this stage does not exclude schistosomiasis because egg output only begins once adult worms mature and start laying eggs, so serology (still pending here) is the more sensitive early test. The freshwater rafting history in an endemic area, combined with the tetrad of fever, urticaria, cough and eosinophilia, is highly specific for this diagnosis and should prompt treatment consideration even before serology returns. Why the other options are wrong: E. Dengue with warning signs: Dengue causes fever and rash but produces lymphopenia or leukopenia and thrombocytopenia rather than eosinophilia, and warning signs (bleeding, plasma leakage) are absent here. A. Acute HIV seroconversion: this can cause fever and rash but does not typically cause eosinophilia, and there is no exposure history (unprotected sex, needles) to suggest it over a clear freshwater exposure. C. Pulmonary tuberculosis: TB has a much longer, indolent onset (weeks to months) with weight loss and night sweats, and does not cause eosinophilia or urticaria; a 5 week acute hypersensitivity picture is inconsistent. D. Visceral larva migrans from Toxocara: this follows exposure to soil or puppies contaminated with Toxocara eggs, not freshwater contact, and there is no matching exposure history. Key point: fever, urticarial rash, dry cough and eosinophilia weeks after freshwater exposure in Africa is Katayama syndrome, and negative stool/urine microscopy at this early stage does not exclude schistosomiasis since egg shedding lags behind symptom onset.

Reference: NaTHNaC (travelhealthpro.org.uk), Schistosomiasis factsheet, National Travel Health Network and Centre, UK, https://travelhealthpro.org.uk/factsheet/28/schistosomiasis