DENGUE ENCEPHALITIS - A TRUE ENTITY

Involvement of the central nervous system in dengue fever and dengue h emorrhagic fever has always been thought to be secondary to vasculitis with resultant fluid extravasation, cerebral edema, hypoperfusion, hy ponatremia, liver failure, and/or renal failure. Thus, the condition h as been referred to as dengue encephalopathy. Encephalitis or direct i nvolvement of the brain by the virus was thought to be unlikely. This paper reports on six children who were seen over a period of two years presenting on the second or third day of illness with dengue encephal itis. The diagnosis was based upon a clinical picture of encephalitis and confirmed by cerebrospinal fluid (CSF) microscopy and electroencep halography changes. All six cases were confirmed dengue infections. De ngue 3 virus was isolated from the CSF of four cases and in one case, dengue 2 was detected by the polymerase chain reaction in both the CSF and blood. In the sixth case, virologic evidence was negative but den gue immunoglobulin M was detected in the CSF and blood. Since the onse t of encephalitis appears early in the course of illness coinciding wi th the viremic phase, we postulate that the virus crosses the blood-br ain barrier and directly invades the brain causing encephalitis. This study provides strong evidence that dengue 2 and 3 viruses have neurov irulent properties and behave similarly to other members of the Flaviv iridae.