Strongyloidiasis before steroids — DTM&H MCQ

Correct answer: B — Ivermectin for suspected Strongyloides stercoralis

The correct answer is B, ivermectin for suspected Strongyloides stercoralis. This patient has classic red-flag features for chronic strongyloidiasis: origin from a Southeast Asian rice-farming region, a history of walking barefoot in soil (filariform larvae penetrate skin), intermittent abdominal pain, and eosinophilia, the hallmark of chronic autoinfective helminth carriage. Strongyloides can persist asymptomatically for decades through an autoinfective cycle, and starting high-dose corticosteroids suppresses the Th2 response that normally contains the parasite, precipitating hyperinfection syndrome or disseminated disease with gram-negative sepsis and meningitis, which carries very high mortality. Guidance is explicit that at-risk patients should be screened for, or empirically treated for, strongyloidiasis before immunosuppression is started, and ivermectin is the treatment of choice given its superior larvicidal efficacy over albendazole. Why the other options are wrong: A. Albendazole single dose for hookworm alone: albendazole targets hookworm but has markedly inferior cure rates against Strongyloides compared with ivermectin, so it does not adequately address the organism of concern here. C. Praziquantel for schistosomiasis: schistosomiasis does not explain this exposure pattern (barefoot walking in rice paddies is the classic strongyloides route) and praziquantel has no activity against Strongyloides. D. Metronidazole for amoebiasis: amoebiasis causes bloody diarrhoea or liver abscess, not eosinophilia, and metronidazole has no strongyloides activity; eosinophilia argues against a protozoal cause. E. Doxycycline for rickettsial infection: rickettsial disease presents with fever, rash and eschar, not chronic abdominal pain with eosinophilia, and doxycycline does nothing to prevent hyperinfection. Key point: Any patient with a history of soil or rice-field exposure and eosinophilia must be treated (or screened) for Strongyloides stercoralis with ivermectin before corticosteroids are given, to prevent fatal hyperinfection syndrome.

Reference: World Gastroenterology Organisation Global Guidelines, Management of Strongyloidiasis, 2018/2020 (screening and presumptive ivermectin treatment before immunosuppression); BNF, Ivermectin monograph, treatment of choice for strongyloidiasis, https://bnf.nice.org.uk/drugs/ivermectin/