Primaquine treatment and relapse in Plasmodium vivax malaria.

The relapsing peculiarity of Plasmodium vivax is one of the prime reasons for sustained global malaria transmission. Global containment of P. vivax is more challenging and crucial compared to other species for achieving total malaria control/elimination. Primaquine (PQ) failure and P. vivax relapse is a major global public health concern. Identification and characterization of different relapse strains of P. vivax prevalent across the globe should be one of the thrust areas in malaria research. Despite renewed and rising global concern by researchers on this once 'neglected' species, research and development on the very topic of P. vivax reappearance remains inadequate. Many malaria endemic countries have not mandated routine glucose-6-phosphate dehydrogenase (G6PD) testing before initiating PQ radical cure in P. vivax malaria. This results in either no PQ prescription or thoughtless prescription and administration of PQ to P. vivax patients by healthcare providers without being concerned about patients' G6PD status and associated complications. It is imperative to ascertain the G6PD status and optimum dissemination of PQ radical cure in all cases of P. vivax malaria across the globe. There persists a compelling need to develop/validate a rapid, easy-to-perform, easy-to-interpret, quality controllable, robust, and cost-effective G6PD assay. High-dose PQ of both standard and short duration appears to be safe and more effective for preventing relapses and should be practiced among patients with normal G6PD activity. Multicentric studies involving adequately representative populations across the globe with reference PQ dose must be carried out to determine the true distribution of PQ failure. Study proving role of cytochrome P450-2D6 gene in PQ metabolism and association of CYP2D6 metabolizer phenotypes and P. vivax relapse is of prime importance and should be carried forward in multicentric systems across the globe.