West-Nile virus encephalitis in an immunocompetent pediatric patient: successful recovery

BACKGROUND: West Nile virus (WNV) is a mosquito-borne RNA virus belonging to the Flaviviridae family. Symptomatic infection happens in only about 20% of the cases, while WNV neuroinvasive disease (WNND) is rare and accounts for less than 1%. There is insufficient information about natural history and clinical course in children, because underdiagnosis is common, and reports are scarce. On the other hand, Europe has seen a dramatic increase of WNV infections in the last decades, and the Po valley itself, in Northern Italy, has become an endemic region since 2013. CASE PRESENTATION: We hereby report a case of West-Nile virus neuroinvasive disease in a 12-year-old boy. This is one of the very few cases diagnosed in the Italian pediatric population. The clinical presentation was compatible with acute encephalitis. Diagnosis was made by detection of specific IgM in both serum and cerebrospinal fluid. He finally was discharged with complete recovery, and no neurologic sequelae after a 12-months follow up period. CONCLUSIONS: Given its non-specific clinical presentation, the diffusion of WNV constitutes a crucial and emerging concern. Even though rare, neuroinvasive WNV infection should always be suspected in pediatric patients, living or traveling in endemic areas, presenting with meningitis, encephalitis or acute flaccid paralysis during the WNV transmission season.