Severe Usutu Virus Encephalitis Treated With Corticosteroids: A Case Report.

Usutu virus (USUV) is a neurotropic flavivirus, phylogenetically related to West Nile virus (WNV), maintained in the environment through a bird-to-mosquito transmission cycle, with humans and other animals occasionally becoming infected. In recent years, different cases of human infections have been reported concomitantly with increased viral circulation in several European countries. Most USUV infections in humans remain asymptomatic; however, neuroinvasive disease has been reported, mainly in the elderly and the immunocompromised but also in healthy individuals. Herein, we report a case of severe USUV meningoencephalitis in an elderly patient treated with a short course of dexamethasone and discuss the potential role of steroids in light of the most recent literature on the pathogenetic mechanisms of arboviral encephalitis.