In our region, around half of all malaria is caused by P. vivax. In contrast with falciparum malaria, vivax malaria can relapse from dormant stage parasites (hypnozoites) in the patient’s liver. Understanding the relapse patterns and origins of relapse infections has been a major topic of research for our team. Primaquine is currently the only available drug to prevent relapse infections. However, this drug can cause severe haemolysis in patients with reduced activity of a specific enzyme (Glucose-6-phosphate dehydrogenase or G6PD) to counter drug-induced oxidative stress.
What is the most effective and safest way to radically cure vivax malaria? The Malaria Department is involved in large treatment trials on the optimal primaquine treatment regimens for radical treatment of vivax malaria in patients with or without G6PD deficiency. In addition to his extensive research portfolio on antimalarial drug resistance and other topics, Dr. Charlie Woodrow leads trials together with Dr. Awab Rahim Ghulam on radical treatment of P. vivax in Afghanistan.
Bob Taylor leads the IMPROV (Improving the Radical Cure of Vivax Malaria) trial, which we are coordinating in collaboration with Ric Price of the Menzies School of Health Research. IMPROV will compare standard dose primaquine for 14 days against high dose primaquine for 7 days at seven sites in five countries.
As antimalarial drug resistance in vivax malaria is an increasing problem as well, we perform studies on in-vivo and in-vitro drug sensitivity of parasites from throughout the region. Dr. Prakaykaew Charunwatthana is investigating in-vivo efficacy of artesunate and chloroquine treatment in P. vivax patients in Thailand. The malaria laboratory is developing a method for long-term in-vitro cultivation of P. vivax, which will greatly facilitate research on this parasite.