Implementation of G6PD testing and primaquine for P. vivax radical cure: Operational perspectives from Thailand and Cambodia.

Following progressive success in reducing the burden of malaria over the past two decades, countries of the Asia Pacific are now aiming for elimination of malaria by 2030. Plasmodium falciparum and Plasmodium vivax are the two main malaria species that are endemic in the region. P. vivax is generally perceived to be less severe but will be harder to eliminate, owing partly to its dormant liver stage (known as a hypnozoite) that can cause multiple relapses following an initial clinical episode caused by a mosquito-borne infection. Primaquine is the only anti-hypnozoite drug against P. vivax relapse currently available, with tafenoquine in the pipeline. However, both drugs may cause severe haemolysis in individuals with deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD), a hereditary defect. The overall incidence of malaria has significantly declined in both Thailand and Cambodia over the last 15 years. However, P. vivax has replaced P. falciparum as the dominant species in large parts of both countries. This paper presents the experience of the national malaria control programmes of the two countries, in their efforts to implement safe primaquine therapy for the radical cure, i.e. relapse prevention, of P. vivax malaria by introducing a rapid, point-of-care test to screen for G6PD deficiency.