Ocular disease resulting from infection with Rift Valley fever virus

Abstract

The demonstration of serological conversion to Rift Valley fever (RVF) virus in paired acute and convalescent sera established RVF as the cause of two cases of retinitis seen during the 1977 RVF epidemic in Egypt. Colour photography of the retina revealed macular, paramacular and extramacular exudate-like lesions with associated haemorrage and oedema. One patient has not recovered central vision during a six-month convalescence. An ongoing study of a larger group of RVF patients with ocular disease revealed that the findings presented for these two cases represented the types of lesions most frequently encountered during the epidemic.

Rift Valley Fever Retinopathy: Observations in A New Outbreak

“…In a report of brain autopsy performed in a fatal case of RVF, 22 perivascular cuffing and round-cell infiltration were noted. This, together with other previous clinical reports, [15][16][17] favors an inflammatory nature of the lesion. In this clinical study our findings suggest that the primary pathology is retinitis and retinal vasculitis resulting in vascular artenolar occlusion.…”

“…The presence of capillary dropout areas, later formation of microangiopathies (mostly microaneurysms) and subsequent macular scarring in the areas of the primary lesions indicates secondary microvascular occlusion to infectious retinal vasculitis. The ambiguous term "exudate-like lesions" used by previous investigators 11,12,[15][16][17] is confusing and does not imply a definite pathology; instead, the lesions should be described as "infectious retinitis. "…”

“…14 Their data suggested that lesions were the result of primary occlusion of the retinal circulation. Siam et al 15,16 reported detailed photographic and fluorographic descriptions of seven serologically diagnosed cases of RVF retinopathy during the 1977 epidemic in Egypt. These authors suggested vasculitis, retinitis, and vascular occlusion as the primary underlying pathologic changes.…”

Potential for Autoimmune Pathogenesis of Rift Valley Fever Virus Retinitis

“…Retinal complications occur in up to 10% of those affected and can cause lasting loss of vision. 6,[10][11][12] Other severe complications can include encephalitis (8%), hepato-renal failure, 8 hepatitis, 10 and hemorrhagic fever (1%).…”

“…Retinal complications occur in up to 10% of those affected and can cause lasting loss of vision. 6,[10][11][12] Other severe complications can include encephalitis (8%), hepato-renal failure, 8 hepatitis, 10 and hemorrhagic fever (1%). 11,13 Case-fatality rates have been reported as high as 31%, but the actual value is likely between 0.5% and 2% because a small proportion of infected persons are diagnosed, 11,13 especially those with milder disease.…”