Primaquine treatment for Plasmodium vivax--an essential tool for malaria control and elimination in Papua New Guinea.

Plasmodium vivax is a major cause of malarial infection and disease in young children in Papua New Guinea. Recent increase in funding for malaria control has improved accessibility to preventive measures, diagnosis and artemisinin combination therapies. Yet the current treatment and control measures are more effective against P. falciparum than against P. vivax and P. ovale due to the biological differences in the liver stage life-cycle of these parasites. P. vivax and P. ovale have a dormant liver stage called a hypnozoite. The artemisinin combination therapies, while highly effective against the blood stages of all plasmodium species causing human malarial illness, have no effect upon the hypnozoites in the liver and the stage V gametocytes of P. falciparum. Currently, primaquine is the only licensed drug shown to be effective against both the hypnozoites of P. vivax and P. ovale in the liver and the stage V gametocytes of P. falciparum. Primaquine has a high associated risk of life-threatening haemolytic anaemia when administered to glucose-6-phosphate dehydrogenase (G6PD)-deficient persons. The lack of cheap, reliable point-of-care testing for the diagnosis of G6PD deficiency remains a major obstacle to the widespread use of primaquine in clinical and public health practice. Furthermore, there is a paucity of primaquine safety and tolerability data, especially in young children with the highest P. vivax disease burden. For malaria control and elimination efforts to be effective, interventions such as mass drug administration must include primaquine. This opinion paper highlights the need to eradicate hypnozoites in the liver of the human host with primaquine treatment for radical cure of malarial illness and discusses the challenges in the use of primaquine as a public health tool for malaria control and elimination programs in countries such as Papua New Guinea.