A 28-year-old woman, 6 weeks pregnant, from endemic Jharkhand presents with a 3-day history of fever (38.8°C), myalgia, and vomiting. Thick blood smear shows *Plasmodium vivax* with 0.5% parasitemia. She is haemodynamically stable, alert, with no jaundice or neurological signs. What is the most appropriate antimalarial regimen?

Explanation

## Clinical Context **Key Point:** This is *Plasmodium vivax* malaria in a pregnant woman. Pregnancy fundamentally alters antimalarial drug selection due to teratogenicity concerns and altered pharmacokinetics. ## Pregnancy-Safe Antimalarials | Drug | Trimester Safety | Notes | |------|------------------|-------| | **Chloroquine** | Safe (all trimesters) | First-line for *P. vivax* in pregnancy; *P. vivax* remains chloroquine-sensitive in most endemic areas | | Artemisinin derivatives | Avoid 1st trimester; caution 2nd/3rd | Teratogenic in animal models; limited human data | | Quinine | Avoid (ototoxicity, hypoglycemia risk) | Contraindicated in pregnancy | | Primaquine | **Contraindicated in pregnancy** | Teratogenic; defer until postpartum | | ACTs (artemether-lumefantrine) | Avoid 1st trimester | Use only if *P. falciparum* and no chloroquine alternative | **High-Yield:** *Plasmodium vivax* is chloroquine-sensitive in India. Chloroquine is the **safest and most effective** agent for *P. vivax* in pregnancy. Primaquine (for hypnozoite eradication) is deferred until after delivery and breastfeeding cessation. ## Treatment Algorithm for Malaria in Pregnancy ```mermaid flowchart TD A[Malaria in pregnancy]:::outcome --> B{Species?}:::decision B -->|P. vivax| C[Chloroquine 600/300/300/300 mg]:::action B -->|P. falciparum| D{Trimester?}:::decision C --> E[Defer primaquine until postpartum]:::action D -->|1st trimester| F[Quinine or chloroquine if sensitive]:::action D -->|2nd/3rd trimester| G[Artemisinin derivative if needed]:::action E --> H[Primaquine 0.75 mg/kg/day × 14 days after delivery]:::action ``` ## Why Not Artemether-Lumefantrine? Artemisinin-based combinations are **second-line in pregnancy**, especially in the 1st trimester. Although this patient is 6 weeks pregnant (1st trimester), chloroquine is preferred for *P. vivax* due to safety data and efficacy. ACTs are reserved for *P. falciparum* when chloroquine resistance is documented. ## Why Not Artesunate or Quinine? - **Artesunate:** Teratogenic in animal models; insufficient human safety data in 1st trimester. Reserved for severe *P. falciparum* malaria when no alternative exists. - **Quinine:** Associated with ototoxicity, hypoglycemia, and uterine contractions in pregnancy. Contraindicated. **Clinical Pearl:** Primaquine eradication of *P. vivax* hypnozoites is essential to prevent relapse, but it is deferred until after delivery and breastfeeding is stopped (primaquine can cause haemolysis in G6PD-deficient neonates). The patient should be counselled about the risk of relapse in the postpartum period. **Mnemonic:** **SAP** = **S**afe in pregnancy: **A**rtemisinins (2nd/3rd trimester only), **P**rimaquine (postpartum only). For *P. vivax* in pregnancy: **CQ** (chloroquine) first, **PQ** (primaquine) later.