Eyes are the windows to malaria

It's often said that the eyes are the windows to the soul, but they can also reveal why malaria infection in the brain is so deadly.    

Malaria is caused by a parasite that gets into the bloodstream through infected mosquito bites, and makes its home in red blood cells.  If infected cells build up in the brain this is known as cerebral malaria, and it can cause coma, convulsions or even kill.  Scientists suspect that the infected red blood cells block the blood vessels in the brain, but they're not exactly sure how this process works. 

It's been known for some time that changes in the retina - the layer of cells at the back of the eyeball - are a hallmark of cerebral malaria. And looking at an infected person's retina can reveal whether they are at risk of it.  

Now with funding from the Wellcome Trust and Fight for Sight, Dr Nick Beare from the Royal Liverpool University Hospital has looked at the retinas of 34 children in hospital in Malawi with cerebral malaria, to try and get some clues as to why the disease is so deadly.

Writing in the Journal of Infectious Diseases, the researchers used  technique  called fluorescein angiography, which involves injecting a fluorescent dye into the bloodstream, then following it as it flows through the body, including the tiny blood vessels in the retina.  More than four in five of the children were found to have faulty blood flow in the blood vessels of their eyes. Three-quarters had areas in their retinas where blood appeared not to be flowing at all, suggesting that the malaria parasites has disrupted the supply of oxygen and nutrients to these areas. 

So although looking at the retina can help doctors to diagnose cerebral malaria, it has now confirmed why it is so deadly - by blocking blood flow to the brain and cutting off the oxygen supply.

The researchers think that their results could point towards new approaches for treating cerebral malaria - using treatments that can improve the circulation and limit the damage caused by a lack of oxygen.  For example, these might include the kind of approaches that doctors are investigating for heart disease and stroke.

Beare et al Journal of Infectious Diseases (2009) vol 199, pp263-271