# Unusual Presentation of West Nile Virus Meningitis With Cerebrospinal Fluid (CSF) Neutrophilia in a 68-Year-Old Male

## TL;DR

A 68-year-old man showed unusual symptoms of West Nile virus meningitis with neutrophils in his cerebrospinal fluid, highlighting the need for early diagnosis.

## Contribution

Reports a rare case of WNV meningitis with atypical CSF neutrophilia, expanding clinical awareness.

## Key findings

- CSF showed neutrophilic pleocytosis instead of the typical lymphocytosis in WNV meningitis.
- WNV IgM was detected in CSF, confirming the diagnosis despite non-classical findings.
- The case emphasizes the importance of considering WNV in meningitis differential diagnosis during mosquito season.

## Abstract

West Nile virus (WNV), a mosquito-borne flavivirus, can cause neuroinvasive disease, including meningitis, encephalitis, and acute flaccid paralysis. WNV meningitis typically presents with lymphocytosis in the cerebrospinal fluid (CSF). We report a case of a 68-year-old male who presented with dizziness, syncope, and head trauma, accompanied by headache, neck pain, and fever (102.3 °F), but without confusion or photophobia. The initial workup was unremarkable, but the lumbar puncture revealed elevated cerebrospinal fluid (CSF) opening pressure, neutrophilic pleocytosis, and increased red blood cells, protein, and glucose levels. CSF serology was positive for WNV IgM, and other infectious etiologies were excluded. This case illustrates that WNV meningitis may present with atypical CSF neutrophilic predominance, emphasizing the need to consider WNV in the differential diagnosis of meningitis, especially during mosquito season or in endemic areas, even when CSF findings are non-classical. Early recognition and diagnostic testing are essential for appropriate management.