West Nile virus encephalitis: Clinical characteristics and a comparison to other infectious encephalitides

To compare functional outcomes and help differentiate between important causative agents of acute infectious encephalitis in adults, focusing on West Nile virus encephalitis (WNVE). The electronic database of Tel Aviv Medical Center was screened for patients admitted during 2010–2020 with acute encephalitis. Additionally, patient laboratory results during the same period were screened for CSF samples positive for common pathogens causing encephalitis. The main patient groups were compared in terms of clinical characteristics and functional outcomes. One hundred and five infectious encephalitis patients were identified. WNVE patients (n = 31) and VZV encephalitis (VZVE) patients (n = 31) were older than HSV1 encephalitis (HSV1E) patients (n = 15) (median ages 73, 76, 51, respectively). WNVE patients had a more prominent inflammatory profile. CSF characteristics significantly differed between groups, with an extreme mononuclear white blood cell predominance in VZVE patients (median 98%). Functional outcomes at discharge were significantly worse in WNVE patients (median modified Rankin Scale score 4 at hospital discharge, 2.5 at last follow-up) when compared with HSV1E patients (2.5, 1, respectively) and VZVE patients (1.5, 1, respectively). In odds with previous reports, WNVE and VZVE in this study were far more prevalent than HSV1E. Differences in clinical characteristics could prove clinically useful early in encephalitis, including an association of WNVE with a relatively prominent inflammatory profile (somewhat resembling a bacterial infection) and an extreme mononuclear white blood cell predominance in VZVE. The detrimental outcome of WNVE emphasizes the need to advance research on WNV infection. •A cohort of 105 adult infectious encephalitis cases from a single medical center in Israel was retrospectively analyzed•WNV and VZV, not HSV1, were the commonest causes of adult infectious encephalitis•WNVE was associated with a worse outcome at discharge than HSV1E and VZVE•Some features may provide early clues in recognizing the infectious encephalitic agent WNV: West Nile virus. HSV1: herpes simplex 1 virus. VZV: varicella-zoster virus. WNVE: West Nile virus encephalitis. HSV1E: herpes simplex 1 virus encephalitis. VZVE: varicella-zoster virus encephalitis.