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Syphilis — SCE Infectious Diseases MCQ

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HardSTIsSyphilisSCE Infectious Diseases

An adult with HIV controlled on efavirenz is diagnosed with Schistosoma mansoni infection. Praziquantel is planned. What interaction requires specialist action?

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Correct answer: C — Plan an ART switch before giving standard-dose praziquantel treatment

Explanation lettering: E = shown as A · A = shown as B · B = shown as D · D = shown as E

C is correct. The efavirenz SmPC reports an approximately 77% reduction in praziquantel exposure, creating a material risk of antiparasitic treatment failure; co-administration is therefore not recommended. Because uncontrolled ART interruption is unsafe, an HIV and tropical-medicine team should plan a compatible ART strategy and definitive schistosomiasis treatment. Dose halving moves in the wrong direction, the mechanism is enzyme induction rather than renal retention, dialysis has no role, and simple dose separation cannot reverse sustained induction.

Reference: Efavirenz 600 mg SmPC: https://www.medicines.org.uk/emc/product/7070/smpc