Moving towards high-dose primaquine or single-dose tafenoquine for Plasmodium vivax treatment in Cambodia: A meeting report from dissemination of results of the EFFORT trial to stakeholders

Authors: Lek Dysoley, Sarah Cassidy-Seyoum, Bipin Adhikari, Aaryan Dahal, Nead Phoumen, Sin Srey, Touch Phalla, Prak Vonn, But Engrkruy, Oum Sovanarath, Hor Mengkea, Pov Rathana, Iv Makara, Pen Kim Heng, Yim Heng, Huot Khlok, Khourn Pong, Tov Moeng, Sam Vantha, Ung Soviet, Rin Ravuth, Voeurng Bunreth, Keo Vannak, Ma Sokhann, Ke Kimmen, Khoy Dy, Siv Samol, Koung Lo, Nuon Sokunthea, Hok Kry, Ly Kanha, Leng Naren, Sarith Oum, Yok Sovann, Ros Channavuth, Chhun Bunmeng, Jayme Hughes, Hannah Brindle, Yang Hu, Sovann Peng, Prum Mardi, Im Chanry, Sodavuth Preap, Socheat Heoy, Farooq Sabawoon, Thoang Sokha, Pascal Ringwald, Caroline A. Lynch, Ric N. Price, Rupam Tripura, Lorenz von Seidlein, Angela Devine, Kamala Thriemer

Stakeholders agreed that treatment guidelines must be inclusive and flexible to allow policy-makers to implement the best available treatments, with decision-making informed by cost-effectiveness analysis and the demand for shorter treatment options.

Cambodia has targeted malaria elimination by 2025. As the malaria burden has decreased in Cambodia, transmission has become more focal, and Plasmodium vivax has become the predominant species. The recurrent nature of P. vivax, due to its dormant liver stages causing relapses, is the main obstacle to malaria elimination in Cambodia. In 2021, Cambodia’s National Center for Parasitology, Entomology and Malaria Control (CNM) rolled out low-dose 14-day primaquine (total dose 3.5 mg/kg) supported by point-of-care quantitative testing for glucose-6-phosphate dehydrogenase deficiency. However, this treatment is limited by poor adherence to its prolonged duration and suboptimal efficacy of the low total dose. The EFFORT clinical trial was conducted in four malaria-endemic countries, including Cambodia, to assess the safety and effectiveness of a 7-day unsupervised high-dose course of primaquine (7 mg/kg total dose) and single dose tafenoquine (300 mg) compared to 14-day unsupervised low-dose primaquine for the treatment of patients presenting with P. vivax malaria. In addition, data were collected on the feasibility and cost-effectiveness of these treatment options. CNM organised the national dissemination of the EFFORT study results on 27 March 2025, to inform key stakeholders and discuss the implications of the study findings for policy and practice in Cambodia.

Published in Malaria Journal

Citation: Malaria Journal, 2026; 25: 2.