A 32-year-old woman from Odisha presents with fever, chills, and headache for 3 days. Blood smear examination reveals Plasmodium vivax parasitemia. She is not pregnant and has no G6PD deficiency. What is the drug of choice for radical cure of P. vivax malaria?

Explanation

## Radical Cure of P. vivax Malaria **Key Point:** Primaquine is the ONLY antimalarial that eliminates hypnozoites (dormant liver forms) of P. vivax and P. ovale, preventing relapses. Chloroquine alone treats only the erythrocytic stage. ### Why Primaquine is Correct **High-Yield:** Primaquine is an 8-aminoquinoline that: - Kills hypnozoites in hepatocytes (the only drug class that does this) - Prevents relapses that occur 2–8 weeks after initial infection - Must be given after acute parasitemia is cleared with chloroquine (or artemisinin derivatives) **Clinical Pearl:** In P. vivax and P. ovale endemic areas, primaquine is mandatory for radical cure. Without it, ~50% of patients relapse. ### Standard Regimen for P. vivax | Phase | Drug | Dose | Duration | Purpose | | --- | --- | --- | --- | --- | | Acute | Chloroquine | 600 mg base day 1–2, then 300 mg days 3–5 | 3 days | Erythrocytic parasites | | Radical | Primaquine | 0.5 mg/kg/day (or 15 mg/day) | 14 days | Hypnozoites | **Mnemonic:** **CHAP** — Chloroquine for Hypnozoites? No. Primaquine for hypnozoites = **P**rimaquine. ### Contraindications to Primaquine - G6PD deficiency (hemolysis risk) — must screen first - Pregnancy (teratogenic) - Severe renal/hepatic disease **Warning:** Chloroquine monotherapy leaves hypnozoites untouched; relapse is inevitable without primaquine in vivax/ovale.