Physical examination showed a positive Kernig sign and negative Brudzinski sign. The patient's cerebrospinal fluid sample was injected into chocolate agar, in which microbial growth was observed after 24 hours.
He had neck stiffness without Kernig sign or Brudzinski sign. Complete blood count showed a leukocyte count of 26,400 cells/[mm.sup.3] and differential of 92.1% neutrophils, 5.3% lymphocytes, 2.6% monocytes, and 0.1% eosinophils; hemoglobin level of 12.9 g/dL; hematocrit 38.6%; and a thrombocyte count of 102,000 cells/[mm.sup.3].
The initial clinical syndrome was classified as WNV encephalitis, indicated by fever and altered mental status or other cortical signs (e.g., seizures) and cerebrospinal fluid (CSF) suggestive of viral infection; WNV meningitis, indicated by fever, meningeal signs (documentation of Kemig sign, Brudzinski sign, or nuchal rigidity), and CSF suggestive of viral infection; or WNV fever with headache.