What is the treatment for Plasmodium vivax (P. vivax) malaria?

From the Guidelines

The treatment of Plasmodium vivax malaria should consist of chloroquine for the blood stage infection, followed by primaquine for radical cure of the liver stage, unless contraindicated due to G6PD deficiency or other factors, in which case alternative treatments such as artemisinin-based combination therapies (ACTs) may be considered. The choice of treatment depends on various factors including the presence of chloroquine resistance in the area where the infection was acquired, the patient's G6PD status, and any potential contraindications to certain medications.

• For the blood stage infection, chloroquine is typically administered at a dose of 600mg base (1000mg salt) orally on day 1, followed by 300mg base (500mg salt) at 6, 24, and 48 hours for a total dose of 1500mg base 1.
• For radical cure targeting the liver stage, primaquine is given at 30mg base daily for 14 days in non-G6PD deficient patients 2.
• In areas with chloroquine resistance, ACTs such as artemether-lumefantrine or dihydroartemisinin-piperaquine are recommended instead of chloroquine 2.
• Before starting primaquine, G6PD status must be checked as the medication can cause hemolysis in G6PD-deficient individuals 2.
• For pregnant women, children under 6 months, and G6PD-deficient patients, primaquine is contraindicated, and chloroquine alone is used with close monitoring for relapse 2.
• Treatment should begin promptly after diagnosis to prevent complications and reduce transmission 3. Some key points to consider in the treatment of P. vivax malaria include:
• The importance of testing for G6PD deficiency before initiating primaquine therapy to avoid the risk of hemolysis 2.
• The need for close monitoring of patients with P. vivax malaria, particularly those who have been treated with chloroquine alone, due to the risk of relapse 2.
• The potential for alternative treatments, such as ACTs, in areas with chloroquine resistance or in patients who are unable to tolerate chloroquine or primaquine 2.

From the FDA Drug Label

Persons with acute attacks of vivax malaria, provoked by the release of erythrocytic forms of the parasite, respond readily to therapy, particularly to chloroquine phosphate. Primaquine eliminate tissue (exoerythrocytic) infection and prevents relapses in experimentally induced vivax malaria in human volunteers and in persons with naturally occurring infections and is a valuable adjunct to conventional therapy in vivax malaria. Mefloquine is indicated for the treatment of mild to moderate acute malaria caused by mefloquine-susceptible strains of P. falciparum (both chloroquine-susceptible and resistant strains) or by Plasmodium vivax. Patients with acute P. vivax malaria, treated with mefloquine, are at high risk of relapse because mefloquine does not eliminate exoerythrocytic (hepatic phase) parasites. To avoid relapse, after initial treatment of the acute infection with mefloquine, patients should subsequently be treated with an 8-aminoquinoline derivative (e.g., primaquine).

The treatment of Plasmodium vivax malaria involves:

• Initial treatment with chloroquine phosphate or mefloquine to address the acute infection
• Subsequent treatment with an 8-aminoquinoline derivative (e.g., primaquine) to eliminate tissue (exoerythrocytic) infection and prevent relapses [4] [5] Key points:
• Mefloquine does not eliminate exoerythrocytic parasites and requires additional treatment with primaquine to prevent relapse
• Primaquine is a valuable adjunct to conventional therapy in vivax malaria

From the Research

Treatment Options for Plasmodium vivax Malaria

• The World Health Organization recommends a 14-day course of primaquine (0.25 mg/kg/day, giving an adult dose of 15 mg/day) to eradicate the liver stage of the parasite and prevent relapse of the disease 6.
• Alternative primaquine regimens, such as a 5-day or 7-day course, have been shown to have higher relapse rates compared to the standard 14-day regimen 6.
• Artemisinin-based combination therapies (ACTs), such as dihydroartemisinin-piperaquine, have been shown to be effective in treating acute uncomplicated P. vivax malaria, and may provide a longer period of post-treatment prophylaxis compared to chloroquine 7.
• The addition of primaquine to ACTs has been shown to reduce the risk of recurrent P. vivax malaria 8.
• Higher-dose primaquine regimens, such as a total dose of 7.0 mg per kilogram, have been shown to have higher efficacy in preventing relapse of P. vivax malaria compared to standard doses 9.

Considerations for Treatment

• The choice of treatment should take into account the presence of glucose-6-phosphate dehydrogenase (G6PD) deficiency, as primaquine can cause hemolytic anemia in individuals with this deficiency 6, 10.
• The efficacy of treatment may vary depending on the specific strain of P. vivax and the level of resistance to chloroquine in the area 7, 10.
• The use of primaquine requires careful consideration of the potential risks and benefits, particularly in patients with G6PD deficiency or other underlying health conditions 6, 10.

Current Research and Recommendations

• Further research is needed to determine the optimal treatment regimens for P. vivax malaria, particularly in areas with high levels of chloroquine resistance 7, 10.
• The World Health Organization recommends the use of ACTs, such as dihydroartemisinin-piperaquine, in combination with primaquine for the treatment of P. vivax malaria 7.
• Higher-dose primaquine regimens may be considered for patients with a high risk of relapse or in areas with high levels of transmission 9.