Malaria elimination possible with expanded use of readily available treatment

The parasite which causes malaria is a sly foe. Once the fog lifts from the infection and you feel yourself getting better, tiny hypnozoites still hide in the liver, which can cause relapses or further spread of the infection.

A new study looked at a readily available treatment for one type of malaria to try and stop this, specifically investigating if the drug primaquine could limit relapses in certain cases.

The research has been published in The Lancet.

Malaria is caused by a number of species of parasite. Plasmodium falciparum is the deadliest, while P. vivax is the most common.

Primaquine is mostly used to prevent relapses of P. vivax infections, but in places with both versions of malaria co-exist, there’s risk of relapses of another strain. 

“We know that in areas where the two most important malaria species are present, the risk of a P. vivax relapse after a P. falciparum infection is high,” said Associate Professor Kamala Thriemer from the Menzies School of Health Research.

“Malaria elimination requires wide-scale provision of safer and more effective antimalarial treatments, this is particularly the case for vivax malaria.”

The team undertook a huge study in Bangladesh, Indonesia, and Ethiopia where those who had been infected with P. falciparum were given oral primaquine over seven days (called the radical cure) or given the standard of care (a single oral dose).

The results were impressive.

“This clinical trial found that using radical cure in patients with P. falciparum malaria has the potential to reduce the risk of future P. vivax episodes,” said Thriemer.

“In patients who received radical cure, the risk of P. vivax reinfection was 5 times lower than in participants who received standard treatment.”

On day 63, the risk of being infected with P. vivax was 11% in the standard care arm, and only 2.5% with the intervention.

There was one more bump in the road though. The researchers had to ensure their patients didn’t have a G6PD enzyme deficiency.

“Primaquine is safe for most patients, but the drug can induce a severe form of anaemia (called haemolysis) in patients with a particular enzyme (G6PD) deficiency,” said Dr Neena Valecha, co-chair of the Asia Pacific Malaria Elimination Network Vivax Working Group.

“With availability of novel diagnostic tools for point of care G6PD testing, universal radical cure can be provided safely and effectively and can help National Programmes to accelerate towards the goal of malaria elimination.”