Radical cure with primaquine reduces risk of Plasmodium vivax parasitaemia in patients with Plasmodium falciparum infection

1. Patients in the primaquine group reported a significant reduction in parasitemia risk at day 63 compared to those in the standard care group.

2. The majority of adverse events were mild-to-moderate with no treatment-related deaths.

Evidence Rating Level: 1 (Excellent)

Study Rundown: In areas where Plasmodium vivax and Plasmodium falciparum coexist, there exists an elevated risk of P. vivax parasitemia following P. falciparum malaria. This randomized controlled trial aimed to assess the efficacy of expanding radical cure indications to P. falciparum patients, potentially reducing subsequent P. vivax parasitemia risk. The primary outcome was the incidence risk of P. vivax parasitemia on day 63, while key secondary outcomes were routine symptom reporting on days 2 and 7. According to study results, administration of high-dose short-course primaquine resulted in a five-fold reduction in P. vivax parasitemia after two-months. Although this study was well-done, it was limited by potential variations in benefits across endemic settings.

Click to read the study in The Lancet

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In-depth [randomized-controlled trial]: Between Aug 18, 2019, and Mar 14, 2022, 500 patients were screened for eligibility in Bangladesh, Indonesia, and Ethiopia. Included were patients with uncomplicated P. falciparum infection in areas co-endemic for P. vivax and P. falciparum. Altogether, 495 patients (246 in intervention and 249 in control) were included in the final analysis. The primary outcome of P. vivax parasitemia at day 63 showed a significant reduction in the intervention group (2.5%, 95% confidence interval [CI] 1.0-5.9) compared to control (11.0%, 95% CI 7.5-15.9; hazard ratio [HR] 0.20, p=0.0009). In contrast, routine symptom reporting on days 2 and 7 showed no significant differences between groups. In the first 42 days, adverse events were reported, with 92% being mild. Overall, findings from this study suggest that high-dose short-course primaquine is safe and significantly reduces the risk of subsequent P. vivax parasitemia, proposing potential benefits for universal radical cure.

Image: PD

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