What is the recommended treatment for malaria vivax?

Treatment of Plasmodium vivax Malaria

The recommended treatment for Plasmodium vivax malaria consists of chloroquine for blood-stage parasites followed by primaquine for radical cure of liver hypnozoites, with G6PD testing required before primaquine administration to prevent potentially life-threatening hemolysis. 1

Blood Stage Treatment

First-line therapy (chloroquine-sensitive areas):

• Chloroquine phosphate: Total dose of 25 mg/kg over 3 days 2, 1
  • Adults: 600 mg (base) initially, then 300 mg at 6,24, and 48 hours 2
  • Children: 10 mg/kg on days 1-2, then 5 mg/kg on day 3 2, 1

Alternative therapy (chloroquine-resistant areas):

• Artemether-lumefantrine: First-line alternative 2, 1

  • Adults >35 kg: 4 tablets at 0 and 8 hours on day 1, then 4 tablets twice daily on days 2-3 (total 24 tablets) 2
  • Must be taken with fatty meal for optimal absorption 2

• Dihydroartemisinin-piperaquine: Second-line alternative 2

• Atovaquone-proguanil: Third-line alternative 2

  • Adults >40 kg: 4 tablets daily for 3 days 2
  • Children (weight-based):
    • 11-20 kg: 1 adult tablet daily for 3 days
    • 21-30 kg: 2 adult tablets daily for 3 days
    • 31-40 kg: 3 adult tablets daily for 3 days 2

Radical Cure (Anti-relapse Therapy)

First-line therapy:

• Primaquine phosphate: Required to eliminate liver hypnozoites and prevent relapse 2, 1, 3
  • Adults: 15 mg (base) daily for 14 days 2, 1, 3
  • Children: 0.3 mg/kg/day for 14 days 2, 1
  • CRITICAL: G6PD testing must be performed before administration 2, 1
  • Should be administered concurrently with chloroquine 3

Alternative therapy:

• Tafenoquine: Single 300 mg dose after G6PD testing 1, 4
  • Requires higher threshold of G6PD activity than primaquine 1
  • May be more effective than primaquine for preventing relapses in some cases 4

Special Considerations

G6PD Deficiency

• In populations with high prevalence of G6PD deficiency (notably Asians), primaquine should not be administered for more than 5 days without G6PD testing 2
• Weekly primaquine (0.75 mg/kg once weekly for 8 weeks) may be considered for patients with mild-to-moderate G6PD deficiency 5

Pregnancy

• Pregnant women should defer anti-relapse therapy until after pregnancy 1
• Chloroquine is safe during pregnancy for blood-stage treatment 2
• Artemether-lumefantrine can be used in all trimesters of pregnancy 2, 1

Monitoring Requirements

• Daily parasitemia monitoring until parasites are cleared 1
• Monitor for hemolysis for 48-72 hours after initiating treatment 1
• Repeat thick smear examination if symptoms persist longer than 3 days 2

Treatment Pitfalls to Avoid

1. Failure to provide radical cure: Without primaquine or tafenoquine, P. vivax will relapse due to persistent liver hypnozoites 1, 5

2. Administering primaquine without G6PD testing: Can cause life-threatening hemolysis in G6PD-deficient patients 2, 1

3. Not considering geographic resistance patterns: Chloroquine resistance in P. vivax is widespread in parts of Indonesia, Papua New Guinea, and other regions 6, 7

4. Inadequate dosing: The dose-response relationship for primaquine is steep, with total doses below 5 mg/kg showing reduced efficacy 8

5. Failure to administer primaquine concurrently: Primaquine should be started alongside chloroquine for optimal efficacy 3

By following these evidence-based guidelines, clinicians can effectively treat P. vivax malaria while minimizing the risk of relapse and adverse events.