Southern California neuroinvasive West Nile virus case series

Approximately 80% of individuals infected with West Nile virus (WNV) are asymptomatic, and less than 1% suffer from neuroinvasion that can result in permanent neurological deficits or mortality. Our institution's location in southern California predisposes it to a sizable case volume of neuroinvasive WNV. A 2-year retrospective study was performed at the Olive View-UCLA Medical Center to identify patients with confirmed WNV infection with neuroinvasion. Patient demographics, neurological exam findings, and laboratory diagnostics were reviewed. Data were tabulated and are presented as percentage, mean ± standard deviation, or median [range]. Twenty-two patients (36.4% female, age 50.2 ± 10.6 years) were identified between 20 August 2012 and 24 September 2013. The most common positive findings on review of symptoms included fever (81.8%), nausea/vomiting (81.8%), and headache (68.2%). Thirteen patients (59.1%) presented with fever defined as ≥ 37.8 °C. Motor strength was reduced in nine patients (40.9%) and eight patients (36.4%) were hyporeflexive. Lumbar puncture was performed in all but three patients (cerebrospinal fluid [CSF] protein 76.8 ± 29.6 mg/dL and glucose 71.0 ± 18.8 mg/dL). Elevated CSF anti-WNV IgM and IgG antibody was detected in 93.8% and 62.5% of the 16 tested cases, respectively. Elevated serum anti-WNV IgM and IgG antibody was detected in 100% and 72.2% of the 18 tested cases, respectively. Encephalitic presentations, with or without focal neurological deficits (e.g., motor weakness, hypotonia), dominated this series. In endemic areas, seasonal presentation of such symptoms should raise suspicion for WNV with neuroinvasion.