Using the Retina to Check for Malaria

Researchers from St Paul’s Eye Unit in Liverpool have recognized specific changes to the retina in patients with malaria infections. These changes are visible with just an ophthalmoscope, which is critical for Africa, where there’s a shortage of expensive medical equipment:

The eye can provide a very reliable way of diagnosing cerebral malaria, researchers in Malawi have shown. By looking at the changes to the retina, doctors are able to determine whether an unconscious child is suffering from this severe form of malaria or another, unrelated illness, leading to the most appropriate treatment…
In research funded by the Wellcome Trust and the National Institutes of Health, a study led by Dr Nick Beare of the St Paul’s Eye Unit, Liverpool, has shown that changes to the retina were the only clinical sign or laboratory test which could distinguish between patients who actually died from cerebral malaria and those with another cause of death. The results of their study are published in the latest edition of the American Journal of Tropical Medicine and Hygiene.
“Over a million people a year die from malaria, and most of these are African children,” explains Dr Beare. “Death is usually caused by cerebral malaria, a severe complication of malaria in which the Plasmodium falciparum malaria parasite causes infection of the capillaries that flow through the tissues of the brain, affecting the brain and central nervous system. This can lead to convulsions, coma and death.”
Cerebral malaria is accompanied by changes in the retina, the light-sensitive tissue at the back of the eye. These changes, known as malarial retinopathy, include white, opaque patches, whitening of the infected blood vessels, bleeding into the retina and swelling of the optic nerve, the nerve that transmits visual signals to the brain. The first two of these signs are unique to severe malaria, and not seen in any other disease.
Malaria parasites live in red blood cells and make them stick to the inside of small blood vessels, particularly in the brain and also the eye. It is thought that this causes the unique whitening of eye blood vessels. The light-sensitive tissue in the eye is also affected because the parasites disrupt the supply of oxygen and nutrients. However, once children recover, their vision does not seem to be affected.

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