Blood group O may protect against malaria

In a step that may bring a cure for malaria closed, scientists in Scotland, the USA, Mali and Kenya have found that African children with the blood group O are two-thirds less likely to fall into a coma or experience severe anaemia, both of which are characteristic of the more serious forms of 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. It is this that causes the severe anaemia during malaria infection because these red blood cells are no longer functional. However group O red blood cells do not easily join rosettes because the cell's surface structure prevents them from sticking togehter well.

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.