A case definition is needed for dengue encephalitis

Neurotropic viruses are the most important cause of encephalitis worldwide, although there is considerable geographical variation in the specific agents responsible. Dengue virus threatens 40% of the global population [ ], and although previously not considered a cause of encephalitis, a large body of clinical and laboratory evidence now supports the hypothesis of dengue neurotropism [ ]. Soares et al. have shown that dengue is the most common agent of viral encephalitis in HIV-negative adolescent and adult patients in a South American setting [ ]. Their work highlights the need for validated diagnostic criteria to aid in the identification of dengue encephalitis. In the dengue patient with signs of central nervous system involvement, acute liver failure, shock, electrolyte derangement, and intracranial hemorrhage should be excluded as other mechanisms of a dengue-associated encephalopathy. The core encephalitic features of fever, headache, reduced level of consciousness, and seizures are typically present. Neuroimaging features suggestive of viral encephalitis may be present though are unreliable [ ]. Demonstration of virus and/or antibody response in the CSF (or with lesser diagnostic value, in the serum) confirms the diagnosis. Validation and adoption of a case definition along these lines will aid clinical practice and research in this field.