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5 June 2017, Bangkok (Thailand) – Doing a rapid test for G6PD deficiency before prescribing the antimalarial drug primaquine to P. vivax malaria patients could be a cost-effective way to improve thousands of lives, say researchers in a study published in PLOS Neglected Tropical Diseases.

The study includes an interactive online tool that can be adapted to other locations to examine the potential costs and benefits of using rapid diagnostic tests for G6PD in different scenarios. 

“This paper is important because it shows that using screening tests for G6PD deficiency before prescribing primaquine could lead to better health outcomes at little or no cost to the healthcare providers,” said study author Angela Devine, a health economist and PhD student based at Mahidol-Oxford Tropical Medicine Research Unit (MORU) in Bangkok.

P. vivax is the dominant malaria parasite in most countries outside of sub-Saharan Africa. One bite from a mosquito carrying P. vivax malaria can cause multiple malaria relapses due to liver parasites called hypnozoites. Primaquine is the only licensed antimalarial drug that can cure the vivax hypnozoites.

Many countries, however, don’t use primaquine because it can cause hemolysis – the rupture of red blood cells – in those who have the genetic disorder G6PD deficiency. In other countries, primaquine is given without G6PD testing, putting patients at unnecessary risk of hemolysis.

New rapid diagnostic tests (RDTs) offer the opportunity to screen for G6PD deficiency prior to treatment with primaquine.

Using data from a recent clinical trial at the Mae Sot-based Shoklo Malaria Research Unit (SMRU), which provides free of charge care to migrants and refugees on the Thai-Myanmar border, the study modelled the cost-effectiveness of using G6PD RDTs on the Thailand-Myanmar border and developed an online model tool that can be used to improve healthcare for thousands of malaria patients around the world.

“Concerns over G6PD testing hamper the widespread use of radical cure for P. vivax malaria. This PlosNTD paper and the online tool provided will be an extremely valuable tool for National Malaria Control Programmes to explore the cost effectiveness of G6PD testing in different endemic settings,” said Prof Ric Price, Professor of Tropical Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, and paper contributor.

The study model provides a useful starting point for policy makers who can vary the assumptions made in the model in keeping with local scenarios and as additional data becomes available. 

“All who present with a clinical vivax infection would benefit from having   this test if only for the increased certainty that it's safe to receive primaquine,” explained Ms. Devine. “In settings where primaquine is given without testing, only those who have G6PD deficiency would benefit directly as it should prevent hemolysis. In settings where primaquine is not used,  the benefit comes from preventing relapses.”

Chart images:

A rapid test for G6PD deficiency before administering primaquine to P. vivax malaria patients would dramatically increase the number that you could treat before seeing a death due to primaquine-induced hemolysis, according to a model developed by MORU researchers. Chart images © MORU 2017.

Reference:

Using G6PD tests to enable the safe treatment of Plasmodium vivax infections with primaquine on the Thailand-Myanmar border: A cost-effectiveness analysis.Devine A, Parmiter M, Chu CS, Bancone G, Nosten F, Price RN, Lubell Y, Yeung S. PLoS Negl Trop Dis 11(5): e0005602, published 24 May 2017.https://doi.org/10.1371/journal.pntd.0005602.

Authors and contributors:

Angela Devine, Minnie Parmiter, Cindy S. Chu, Germana Bancone, François Nosten, Ric N. Price, Yoel Lubell and Shunmay Yeung.

Notes for editors:

Mahidol-Oxford Tropical Medicine Research Unit (MORU), www.tropmedres.ac.  

The Mahidol-Oxford Tropical Medicine Research Unit (MORU), www.tropmedres.ac, is a research collaboration between Mahidol University in Thailand and Oxford University and the Wellcome Trust in the UK.

A unit of the Mahidol Oxford Tropical Medicine Research Unit (MORU), the Shoklo Malaria Research Unit (SMRU) is based in Mae Sot, Thailand, and works in the refugee camps and migrant communities along the Thai-Myanmar border.

This research was funded with the support of the Wellcome Trust (UK) and the Bill & Melinda Gates Foundation (USA).

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