Scientists Discover that Vivax Malaria Has Shaped the Evolution of the Human Genome in the Asia-Pacific Region

"Humans and malaria parasites have been co-evolving for thousands of years", says Professor Ivo Mueller, a scientist at CRESIB, ISGlobal's research centre, and the Walter and Eliza Hall Institute. "Malaria has been a major force in the evolution of the human genome, with gene mutations that provide humans with some protection against the disease. It has long been assumed that P. falciparum, the species that causes the most severe disease and most deaths from malaria, is the most important driver of this gene selection in humans". However, the results of a study just published in PLoS Medicine suggest that P. vivax malaria, considered until recently to be a "benign" form of malaria, is deadlier than originally believed and actually causes severe enough disease to provide evolutionary selection pressures in the Asia-Pacific region.

The study, conducted by an international team of researchers led by Professor Mueller, investigated Southeast Asian ovalocytosis (SAO), a hereditary red blood cell disorder, which is unusually common in areas of the Asia-Pacific region where malaria is endemic, in particular, Malaysia and Papua New Guinea. This coincidence suggests that there may be a relationship between SAO and malaria protection in these populations.

The researchers examined the incidence of malaria in 3 studies including 1,975 children aged 0 to 14 years in Papua New Guinea. "We found that SAO-positive children were significantly protected against P. vivax infection, with reduction of risk of infection of 46% in infants aged between 3 and 21 months and an even higher reduction (55%) in older children", said Professor Mueller.

The results suggest that P. vivax is responsible for this genetic variation that protects against malaria. This discovery challenges the general perception that the deadliest of the malaria parasites, P. falciparum, is the only parasite capable of shaping the evolution of the human genome.

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