Strongyloides hyperinfection — DTM&H MCQ

Correct answer: E — Strongyloides hyperinfection

The correct answer is E, Strongyloides hyperinfection. The vignette's key discriminators are corticosteroid exposure in a patient from a Strongyloides-endemic tropical region (rural Thailand), abdominal pain, Gram-negative sepsis, diffuse pulmonary infiltrates, and filariform larvae recovered from sputum. Corticosteroids blunt the eosinophilic and Th2-mediated immune control of Strongyloides stercoralis autoinfection, permitting massive larval multiplication and migration through the gut wall and into the lungs, a process that carries enteric Gram-negative bacteria into the bloodstream and causes the characteristic polymicrobial sepsis. This is the single most common precipitant of hyperinfection syndrome, and finding larvae in sputum in this clinical context is essentially diagnostic. Why the other options are wrong: A. Toxocariasis: This causes visceral or ocular larva migrans with eosinophilia and hepatic or pulmonary granulomas, but larvae are not found in sputum and Gram-negative sepsis is not a feature. D. Paragonimiasis: Lung fluke infection causes haemoptysis and eosinophilic pleuropulmonary disease with eggs, not larvae, seen in sputum, and it is not linked to corticosteroid-driven autoinfection or bacterial sepsis. B. Ascariasis with Loffler syndrome: This produces transient eosinophilic pneumonitis during larval lung migration in a primary infection, not a steroid-triggered autoinfective hyperinfection with sepsis. C. Hookworm anaemia: Hookworm causes chronic iron deficiency anaemia from intestinal blood loss, not pulmonary larvae, sepsis or a steroid-related hyperinfection state. Key point: Corticosteroids in anyone with past tropical soil exposure can trigger Strongyloides hyperinfection with Gram-negative sepsis and larvae in sputum, so screening or empirical ivermectin before immunosuppression is essential.

Reference: PMC (Journal of Neurosurgery: Case Lessons), Strongyloides hyperinfection syndrome due to corticosteroid therapy after resection of meningioma, 2022, https://thejns.org/caselessons/view/journals/j-neurosurg-case-lessons/4/2/article-CASE21667.xml