What is the treatment for Plasmodium malariae?

Treatment of Plasmodium Malariae

Treat uncomplicated P. malariae malaria with chloroquine: 600 mg base initially, followed by 300 mg base at 24 hours, and 150 mg base at 48 hours (total 1,500 mg base over 3 days). 1, 2, 3

Why Chloroquine Remains First-Line

• P. malariae has not developed chloroquine resistance, unlike P. falciparum which shows widespread resistance globally 4, 5
• Chloroquine is safe during pregnancy and can be used in all trimesters 1, 2
• The FDA-approved dosing for adults is 1 g salt (600 mg base) initially, then 500 mg salt (300 mg base) at 6-8 hours, followed by 500 mg salt daily for 2 consecutive days 3

Pediatric Dosing

• Children require 25 mg/kg total dose over 3 days: 10 mg/kg base on day 0,10 mg/kg base at 24 hours, and 5 mg/kg base at 48 hours 1, 2
• The pediatric dose should never exceed the adult dose regardless of weight 3

Critical Distinction: No Primaquine Needed

• P. malariae does NOT require primaquine for radical cure because it lacks the hypnozoite liver stage that causes relapses 1
• This is a key difference from P. vivax and P. ovale, which do require 8-aminoquinoline therapy 1, 2
• Adding primaquine unnecessarily exposes patients to risk of hemolysis without any benefit 1

When to Consider Alternative Therapy

• If chloroquine-resistant P. malariae is suspected (extremely rare), artemisinin-based combination therapy (ACT) can be used 6, 7
• Artemether-lumefantrine: 4 tablets at 0 and 8 hours on day 1, then 4 tablets twice daily on days 2-3, taken with fatty food 6, 7
• Dihydroartemisinin-piperaquine: 3-4 tablets daily for 3 days (based on weight), taken while fasting 6, 7

Monitoring and Follow-Up

• Administer the first chloroquine dose when blood smear is obtained 2
• If symptoms persist beyond 3 days, obtain repeat blood smear to assess parasitemia reduction 1, 2
• Expect clinical improvement within 48 hours and confirm parasite clearance with follow-up blood smears 2

Supportive Care

• Use acetaminophen/paracetamol for fever control 7, 2
• Increase fluid intake to prevent dehydration from febrile illness 7, 2
• For children with high fevers, frequent tepid water sponging is recommended 1, 7

Common Pitfalls to Avoid

• Do not add primaquine routinely - P. malariae has no hypnozoite stage and primaquine adds unnecessary hemolysis risk 1
• Do not confuse P. malariae with P. vivax or P. ovale, which do require primaquine for radical cure 1, 2
• Minor chloroquine side effects include gastrointestinal disturbance, headache, dizziness, and blurred vision, but serious adverse effects are rare at prophylactic doses 2
• Chloroquine may exacerbate psoriasis and interfere with antibody response to intradermal rabies vaccine 2

Severe Malaria (Rare with P. Malariae)

• If severe malaria develops (impaired consciousness, shock, pulmonary edema, acidosis, severe anemia), intravenous artesunate is first-line therapy: 2.4 mg/kg IV at 0,12, and 24 hours 7, 2
• Transition to oral chloroquine when parasitemia is <1% and patient can tolerate oral medication 7