2.85 billion people lived at risk of malaria in 2009

A new evidence-based global distribution map has revealed that that 2.85 billion people lived at risk of infection with Plasmodium vivax parasite in 2009.

91% of them live in Central and South East Asia.

The map uses new global maps of the protective Duffy negativity blood condition - to estimate global populations at risk.

More than half of those exposed to this risk live in areas where P vivax malaria transmission is extremely low or unstable and where prospects of sustained control and elimination are relatively good.

Risk areas were refined using temperature and aridity data based upon their relationship with parasite and vector bionomics.

Medical intelligence was used to modify risk in specific areas where transmission was reported as absent.

"We can now focus on trying to model the endemicity of the disease to provide more detailed global burden estimates, although this is complicated by the unusual biology of P vivax," said Dr. Simon Hay of the University of Oxford.

"Understanding where transmission of this parasite occurs at the global scale is fundamental in planning strategies for the control of this debilitating, and often lethal, disease," added Dr Carlos Guerra.

The research is published in the journal PLoS Neglected Tropical Diseases.