Cerebral malaria can be diagnosed by a simple eye examination, a method that is both quick and cheap and could save thousands of lives in malarial regions, a new study shows.

Diagnosing cerebral malaria — a severe complication of malaria in which the Plasmodium falciparum parasite infects capillaries that flow through the tissues of the brain — can be difficult, as patients can be unconscious and have a number of other illnesses.

Now researchers have found that certain changes on the retina, the light sensitive tissue at the back of the eye, are unique to severe forms of malaria.

This will enable doctors to determine whether a child is suffering from cerebral malaria or some other, unrelated illness, and prescribe immediate treatment accordingly.

The findings are published this week (6 November) in the American Journal of Tropical Medicine and Hygiene.

The team led by Nick Beare of the UK-based Royal Liverpool University Hospital analysed the retinas of 45 children admitted to hospital in Blantyre, Malawi with cerebral malaria.

They found that white opaque patches and whitened blood vessels on the retina were unique signs of cerebral malaria. Other signs include bleeding of the retina and swelling of the optic nerve.

The diagnosis only requires an instrument called an ophthalmoscope, which is commonly used in Africa for studying eye disease.

“Diagnosis requires special training in eye examination, but is relatively straightforward and cost effective, which is essential in resource-poor settings such as Africa,” says Beare.

His team suggests that the malaria parasites stick to the linings of the small blood vessels in the brain and eyes where they disrupt oxygen and nutrients supply, causing the unique whitening of blood vessels in the eye.

Richard Idro of the Kenya Medical Research Institute says that the specific nature of the changes in the eye makes them useful for differentiating between coma due to malaria and coma from other causes.

A multi-centre evaluation of the findings will be undertaken by researchers in Gabon, the Gambia, Ghana and Kenya. “If they prove useful, doctors will need to be trained in the recognition of these signs,” says Idro.

Willis Akhwale, head of the department of malaria control at Kenya’s Ministry of Heath, welcomed the study, but cautioned that it is vital to test the methodology to ensure that correct diagnosis is made so that malaria drugs are not prescribed for other illnesses.