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Vivax Relapse Prevention — RACP Adult Medicine MCQ

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ModerateInfectious DiseasesVivax Relapse PreventionRACP Adult Medicine

A 25-year-old woman returned from India 6 months ago presents with relapsing fevers. Initial blood film showed P. vivax which was treated with chloroquine. Symptoms recurred despite adequate treatment. She is G6PD normal. What is the most important additional treatment to prevent relapse?

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Correct answer: D — Primaquine 14-day course

P. vivax and P. ovale form hypnozoites (dormant liver stages) that cause relapse months-years after initial infection. Anti-hypnozoite therapy is required to prevent relapse: primaquine (0.5 mg/kg/day for 14 days or 0.75 mg/kg/week for 8 weeks) OR tafenoquine (single-dose — recently approved). Both cause haemolytic anaemia in G6PD deficiency — G6PD testing is MANDATORY before prescribing. This patient is G6PD normal so primaquine is safe.

Reference: eTG Antibiotic – 2025 – Vivax Malaria; WHO 2024