Reducing the risk of Plasmodium vivax after P.falciparum infections in co-endemic areas – a randomized controlled trial

November 24, 2022

Plasmodium vivax forms dormant liver stages that can reactivate weeks or months following an acute infection. There is an increased risk of P. vivax parasitaemia following falciparum malaria suggesting radical cure (killing dormant stages) could be beneficial in patients presenting with P. falciparum as well as P. vivax malaria.

We conducted a multicentre, randomized, controlled, open label trial in Bangladesh, Indonesia and Ethiopia. Patients with uncomplicated falciparum malaria, ≥70% G6PD activity and hemoglobin levels ≥8g/dl were enrolled and randomized in a 1:1 ratio to either receive standard blood schizonticidal treatment plus 7-day high dose primaquine (total dose 7mg/kg) or standard blood schizonticidal treatment alone. Patients were followed up weekly until day 63. The primary endpoint is the incidence risk of any P. vivax parasitemia at day 63. Secondary outcomes include the proportion of adverse events and serious adverse events, the incidence risk of severe and very severe anaemia (Hb<5g/dl and <7g/dl) and/or the risk for blood transfusion and the incidence risk of a ≥ 25% fall in haemoglobin with and without hemoglobinuria. The trial is registered at (NCT 03916003). Between 18th August 2019 and 14th March 2022 a total of 500 patients were enrolled and followed for up to 63 days. The study has generated important data with policy and practice implications for countries co-endemic for both P. falciparum and P. vivax.

Associate Professor Kamala Ley-Thriemer, Menzies School of Health Research