Look for Ocular Findings in Cerebral Malaria and Dengue
Abstract & Commentary
By Maria D. Mileno, MD
Maria D. Mileno is Director of Travel Medicine, The Miriam Hospital, and Associate Professor of Medicine (Infectious Diseases) Director, International Travelers Clinic, Brown University School of Medicine, Providence, RI.
Dr. Mileno is a consultant for GlaxoSmithKline.
Synopsis: A symposium of the ASTMH meetings in Atlanta last November focused on eye findings which may be the most reliable indication of cerebral sequestration of malarial parasites, short of brain biopsy.
Sources: 55th Annual Meetings. American Society of Tropical Medicine and Hygiene, Atlanta, Georgia, November 2006. Symposium 53. Terry Taylor, Chair. Malarial Retinopathy: Clinical Features, Pathological Correlations and Implications for the Pathogenesis of Severe Malaria. Lewallen S, et al. Classifying and grading retinal signs in severe malaria. Tropical Doctor. 2006; 36 (suppl. 1): 1-13.
Lewallen et al described a cluster of retinal findings upon examination of persons with severe malaria that was termed malarial retinopathy in 1993. Since then studies of childhood malaria have yielded new information on disease prognosis and prediction of death based upon the described clinical features of malarial retinopathy. Dengue, however, has other more readily identifiable findings. A case of dengue-associated maculopathy has been reported and will be described here, although this entity remains rare.
A constellation of retinal changes specific to severe malaria and includes retinal whitening, blood vessel abnormalities and white-centered hemorrhages constitutes one of the most consistent associations with the phenomenon of cerebral red blood cell sequestration available to the clinician caring for patients with severe malaria, according to reports presented by Dr. Susan Lewallen from the Kilimanjaro Centre for Community Ophthalmology Moshi, Tanzania. Studies of severe childhood malaria in Africa over the last 10 to 15 years have led to better diagnosis and treatment of malaria and through this effort detailed studies of these associated eye findings were obtained.
The diagnosis of cerebral malaria is most often made on clinical grounds - coma in the presence of Plasmodium falciparum parasites in peripheral blood and absence of other causes for coma. A recent postmortem study of children dying with malaria parasitemia and the clinical diagnosis of cerebral malaria did not have pathological features associated with cerebral malaria and actually had other identifiable causes of death. Many children who present with mental status changes in Africa have incidental parasitemia , however, cerebral malaria carries a 15-50% mortality rate, even with treatment. Further understanding of the clinical significance of malarial parasitemia is needed. Between 1999 and 2005, a group of 879 children who were admitted with malaria parasitemia, a significant coma score, no other obvious explanation for coma was evaluated by an ophthalmologist using an indirect dilated eye exam. It should be noted that undilated eyes reveal approximately 1/100th of retinal surface area. Normal fundi were documented in 326 (37%) while 41% had hemorrhage, 46% had macular whitening and 46% had vessel changes described as tram-lining of the vessels in which an orange or white color is seen at the margin of the vascular blood column. Detailed descriptive indicators gradings and definitions of specific lesions are outlined in the Tropical Doctor publication and the report from Malawi.1 Ninety-nine patients had more than one abnormality. Only 27% had papilledema, a nonspecific but severe and worrisome change, but one that that may be indicative of other contributing pathology. Of those with a normal fundus 7% died due to other causes. Patients with malarial retinopathy had a 15% case fatality rate. Persons with papilledema alone, or papilledema with retinopathy had a 44% case fatality rate.
Commentary
In this study ocular findings were the single most reliable indicator of cerebral red blood cell sequestration. Beare et al have indicated that there are four main components of malarial retinopathy; retinal whitening, changes in blood vessels (consisting of discoloration of vessels from orange to white), retinal hemorrhages and papilledema. The first 2 are felt to be specific for malaria. When papilledema is seen without these other changes to suggest malaria alternate causes of increased in intracranial pressure must be considered. Ophthalmologic examination by a straightforward indirect dilated eye exam may aid in a more accurate diagnosis of cerebral malaria and providing a prognosis for adults, as well as children, who present with coma and parasitemia.
A recent report found ocular abnormality in a dengue patient. A 31-year-old man with fever, rash, headache and myalgia presented following a trip to Malaysia. There were no hemorrhagic manifestations. The lowest platelet count was 71,000/µl and dengue serology was positive. On day 8 of his illness he complained of bilateral blurred vision. Detailed visual exam showed diminished visual acuity and fundoscopy revealed dilated veins, hyperemic optic discs, flame and blot hemorrhages soft exudates and macular edema. High-dose corticosteroids were initiated; both visual acuity as well as color vision improved.
Screening returned travelers with fever with more complete ophthalmologic exams may reveal eye ground changes that will greatly influence not only their course of management but also their visual outcomes.
Reference:
- Beare NAV, Taylor TE, Harding SP, LeWallen S, Molyneux. Malarial retinopathy: A new established diagnostic sign in severe malaria. Am J Trop Med Hyg. 2006;75(5):790-797.
Sources:
Taylor TE, et al. Differentiating the pathologies of cerebral malaria by post mortem parasite counts. Nature Med. 2004;10:143-145.
Tan, SY, et al. Dengue maculopathy: A case report. Travel Medicine and Infectious Disease. 2007;5:1:62-63.
Lewallen et al described a cluster of retinal findings upon examination of persons with severe malaria that was termed malarial retinopathy in 1993.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content