New research from Scotland has led to a discovery which may bring a cure for malaria a step closer.
Scientists at Edinburgh University have revealed that people with the blood group "O" are naturally protected from the most severe forms of malaria.
They hope the discovery will lead to new research for drugs or vaccines which recreate the protection offered by this blood type, which is common in tropical countries.
The Scottish team along with researchers in the United States, Mali and Kenya studied African children and found that those with blood type O were two-thirds less likely to fall into a coma or experience life-threatening anaemia which are characteristic of severe malaria.
The scientists believe that creating drugs or vaccines which mimic the effect of having group O red blood cells could dramatically reduce the severe and often fatal complications associated with malaria.
Dr. Alex Rowe, of Edinburgh University's School of Biological Sciences, says the discovery explains why some people are less likely to suffer from life- threatening malaria than others.
In fatal malaria the red blood cells which are infected by parasites block blood vessels which supply oxygen to the brain; malarial parasites arm the blood cell's surface with proteins which stick to blood vessel walls.
These proteins recruit healthy red blood cells to stick to the parasite, encasing the infected red blood cell inside a so-called rosette; this creates a blockage, and the disease worsens.
However group O red blood cells do not easily join rosettes as the cell's surface structure prevents it from sticking fully.
Dr. Rowe says if a drug or a vaccine can be developed to reduce rosetting and mimic the effect of being blood group O, it may be possible to reduce the number of children dying from severe malaria in sub-Saharan Africa.
Malaria currently causes up to two million deaths each year.
The research was funded by the Wellcome Trust and the National Institutes of Health.