What is the specific treatment for a 30-year-old male patient with Plasmodium vivax (P. vivax) malaria?

From the Guidelines

For a 30-year-old male with confirmed Plasmodium vivax malaria, the recommended treatment is a combination of chloroquine followed by primaquine, as stated in the most recent guidelines 1.

Treatment Regimen

The patient should receive chloroquine phosphate 600 mg base (1000 mg salt) orally as an initial dose, followed by 300 mg base (500 mg salt) at 6,24, and 48 hours after the first dose, as outlined in the study by 1.

• This completes the chloroquine course.
• To prevent relapse, primaquine 30 mg base daily for 14 days should be administered, as recommended by 1 and 1.

Important Considerations

Before starting primaquine, the patient should be tested for G6PD deficiency since primaquine can cause hemolysis in G6PD-deficient individuals, as noted in 1 and 1.

• If the patient is G6PD deficient, alternative dosing regimens with lower doses or extended duration may be needed under close medical supervision.

Supportive Care

During treatment, the patient should be monitored for clinical improvement, typically expected within 48-72 hours.

• Adequate hydration, antipyretics for fever, and rest are important supportive measures.

Rationale

This two-drug approach is necessary because chloroquine kills blood-stage parasites responsible for clinical symptoms, while primaquine eliminates hypnozoites (dormant liver forms) that can cause relapses if not treated, as explained in 1.

• P. vivax has a high relapse rate without proper primaquine treatment, so completing the full course is essential for cure.

From the FDA Drug Label

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 specific treatment for a 30-year-old male patient with Plasmodium vivax (P. vivax) malaria is:

• Initial treatment with mefloquine to treat the acute infection
• Subsequent treatment with an 8-aminoquinoline derivative (e.g., primaquine) to prevent relapse, as mefloquine does not eliminate the hepatic phase parasites 2.

From the Research

Treatment for Plasmodium vivax Malaria

The treatment for a 30-year-old male patient with Plasmodium vivax (P. vivax) malaria is as follows:

• The standard treatment for P. vivax malaria is a combination of chloroquine and primaquine 3.
• However, in cases where chloroquine resistance is present, alternative treatments such as atovaquone and proguanil followed by primaquine may be effective 3.
• Primaquine is used to target the dormant liver stages of P. vivax and prevent relapse 4, 5, 6.
• The dosage and duration of primaquine treatment may vary depending on the patient's glucose-6-phosphate dehydrogenase (G6PD) status and the prevalence of G6PD deficiency in the population 4, 5, 6.
• Alternative dosing schedules for primaquine, such as 0.5 mg/kg/day for 7 days or 0.75 mg/kg/week for 8 weeks, may be effective and safer for patients with G6PD deficiency 6.

Considerations for G6PD Deficiency

• G6PD deficiency is a common enzymopathy that can increase the risk of haemolysis in patients taking primaquine 4, 5, 6.
• G6PD testing is recommended before prescribing primaquine to patients with unknown G6PD status 4, 5, 6.
• Patients with G6PD deficiency may require alternative treatments or dosing schedules to minimize the risk of haemolysis 4, 5, 6.

Efficacy and Safety of Treatment

• The efficacy and safety of primaquine treatment for P. vivax malaria have been evaluated in several studies 3, 5, 6.
• The results suggest that primaquine is effective in preventing relapse and reducing the risk of haemolysis in patients with G6PD deficiency 3, 5, 6.
• However, further research is needed to determine the optimal dosing schedule and treatment regimen for patients with P. vivax malaria 6.