Plasmodium vivax (Pv) is a less widely studied form of the malaria parasite but it still infects over 20 million people each year. Most of these cases occur in the Asia Pacific region where more than 2.2 billion people are at risk of infection.
Globally, many countries progress towards malaria elimination, it is now imperative to focus greater resources on tackling Pv malaria to achieve this major public health goal. The challenge is that Pv can relapse due to hypnozoites, liver stage parasite which are not affected by Artemisinin Combination Therapies such as artesunate-mefloquine among others. The only 8-aminoquinoline drugs such as primaquine (PQ) and tafenoquine (TQ) are effective against hypnozoites. The standard treatment course of PQ is 14 days and TQ single dose but both PQ and TQ can cause severe haemolysis in people with severe forms of G6PD deficiency. The status of G6PD deficiency is varied from country to country. Due to availability and implementation challenges of G6PD testing at point of care, many countries in the Mekong region including Myanmar use PQ radical therapy to tackle this Pv upsurge without G6PD testing.
In Cambodia, Pv malaria is a concern for malaria control and elimination since number and proportion of Pv cases have increased as compared to overall malaria caseload. Pv cases have been identified repeatedly among the same patients several times within the same year. The radical treatment of Pv with primaquine (PQ) has been part of the 2014 National Treatment Guidelines but the implementation has not yet been started due to lack of operational experience in deploying G6PD testing.
Recently, CNM/Cambodia and partner initiated to start Pv radical therapy, as an operational research platform, through Global Fund and other funding sources to evaluate the feasibility and acceptability of this radical cure model in order to provide evidence needed to support the scaling up of G6PD testing and radical cure for Pv so that Cambodia can come closer to reaching the goal of malaria elimination by 2025.