Malarial retinopathy: a newly established diagnostic sign in severe malaria

Abstract

Severe malaria is commonly misdiagnosed in Africa, leading to a failure to treat other life-threatening illnesses. In malaria-endemic areas, parasitemia does not ensure a diagnosis of severe malaria because parasitemia can be incidental to other concurrent disease. The detection of malarial retinopathy is a candidate diagnostic test for cerebral malaria. Malarial retinopathy consists of a set of retinal abnormalities that is unique to severe malaria and common in children with cerebral malaria. Its presence and severity are related to risk of death and length of coma in survivors. A large, prospective autopsy study of children dying with cerebral malaria in Malawi found that malarial retinopathy was better than any other clinical or laboratory feature in distinguishing malarial from non-malarial coma. However, visualization has to date relied on specialist examination techniques. Further studies are planned to evaluate the usefulness of funduscopy by general clinicians in a variety of settings across Africa. Studies of the retina and retinal blood vessels provide an unparalleled opportunity to visualize an infected microvasculature and its effect on neural tissue in vivo. This report reviews current knowledge of malarial retinopathy, including its use as a diagnostic test in the comatose child, and its value as a tool for research into the pathophysiology of cerebral malaria.

FIGURE 1

Severe macular whitening (solid arrow) completely surrounding the foveola of a Malawian child with cerebral malaria. Papilledema is present as well as a white-centered hemorrhage temporal to the macula and cotton wool spots above superior temporal arcade. The open arrow indicates glare (photographs provided by Nicholas A. V. Beare).

FIGURE 2

Macular whitening around inferior fovea and temporal macula (solid black arrow). White-centered hemorrhages are temporal to the disc and on the superior macula. Peripheral whitening is outside the vascular arcades (solid white arrow). Open arrow indicates glare.

FIGURE 3

White retinal vessels in an area of confluent peripheral retinal whitening.

FIGURE 4

Vessel changes in same child as in Figure 1, including examples of tramlining (solid arrow) and orange vessel (open arrow).

FIGURE 5

Large number of retinal hemorrhages in a child with cerebral malaria.

FIGURE 6

Clinician performing indirect ophthalmoscopy. This figure appears in color at www.ajtmh.org.

FIGURE 7

Proposed algorithm for use of funduscopic findings in a parasitemic comatose child in a malaria-endemic area. This algorithm will be tested by a multicenter SMAC trial. ICP = intracranial pressure; SMAC = severe malaria in African children clinical network.