What alternative treatment can be given to a pregnant woman with vivax (Plasmodium vivax) malaria instead of primaquine?

Treatment of Vivax Malaria in Pregnancy

For pregnant women with vivax malaria, use chloroquine for acute treatment and continue weekly chloroquine prophylaxis throughout pregnancy to prevent relapses, deferring primaquine until after delivery. 1

Acute Treatment Regimen

• Treat the acute P. vivax infection with standard chloroquine dosing: 600 mg base initially, followed by 600 mg at 24 hours, and 300 mg at 48 hours (total 1,500 mg base over 3 days, approximately 25 mg/kg body weight) 1
• Chloroquine is safe throughout all trimesters of pregnancy and has not been found to have harmful effects on the fetus when used at recommended doses 1
• Pregnant women with malaria should be treated aggressively using the same regimen as non-pregnant adults 1

Prevention of Relapses During Pregnancy

The critical issue is that primaquine cannot be used during pregnancy because it may pass transplacentally to a G6PD-deficient fetus and cause life-threatening hemolytic anemia in utero. 1

Weekly Chloroquine Prophylaxis Strategy

• Continue chloroquine 300 mg base (500 mg phosphate) once weekly from the time of acute treatment until delivery to suppress relapses and prevent recurrences 1, 2
• This approach is highly effective: in a randomized controlled trial of 1,000 pregnant women, weekly chloroquine prophylaxis completely prevented P. vivax episodes (0% vs 10.1% in placebo group) 2
• Weekly prophylaxis was well tolerated with no impact on maternal anemia, birth weight, gestational age, or infant development at 1 year 2

Evidence Supporting This Approach

• Without primaquine, 23% of pregnant women experience P. vivax recurrences within 12 weeks after initial infection, with 86% of these attributable to relapses rather than new infections 3
• Model simulations suggest that weekly chloroquine prophylaxis extending 4-12 weeks can reduce the risk of P. vivax recurrences by 20-65% 3
• Chloroquine treatment in first trimester pregnancy showed no increased rates of spontaneous abortion (22.9% vs 17.8% in unexposed women, P=0.42), congenital abnormalities, stillbirth, or low birth weight 4

Post-Delivery Management

• After delivery, reassess the patient for definitive radical cure with primaquine (15 mg daily for 14 days in adults) to eliminate hypnozoites and prevent future relapses 1
• If breastfeeding, primaquine can be used as very small amounts are secreted in breast milk and are not harmful to the nursing infant 1
• Before administering primaquine, test for G6PD deficiency whenever possible to prevent hemolysis, particularly in high-risk populations such as Asians 1

Critical Caveats

• Monitor for chloroquine resistance in your region, though P. vivax resistance to chloroquine is less common than P. falciparum resistance 5
• If parasitemia persists beyond day 6-7 or symptoms continue beyond 3 days, consider alternative diagnoses or resistant parasites 1, 4
• The quantity of antimalarials transferred in breast milk is insufficient to protect the infant, so breastfed infants requiring chemoprophylaxis must receive their own appropriate dosages 1