West Nile Virus Antibodies (IgG, IgM), CSF

WNILC

36597

2 mL CSF collected in a sterile, plastic leak-proof container

0.7 mL

Refrigerated (cold packs)

Room temperature: 4 days
Refrigerated: 7 days
Frozen: 30 days

Gross hemolysis • Grossly icteric

Set up: Mon, Wed, Fri; Report available: Next day after receipt at the performing laboratory. Add two (2) days for transport.

West Nile Virus Ab (IgG), CSF	<1.30
West Nile Virus Ab (IgM), CSF	<0.90

Interpretive Criteria
West Nile Virus Antibody (IgG), CSF

<1.30	Antibody not detected
1.30-1.49	Equivocal
>1.49	Antibody detected

West Nile Virus Antibody (IgM), CSF

<0.90	Antibody not detected
0.90-1.10	Equivocal
>1.10	Antibody detected

The West Nile Virus (WNV) is a single-stranded RNA virus of the Flaviviridae family. Like other arboviruses (e.g., St. Louis Encephalitis, Dengue Fever, and Yellow Fever), its main route of transmission to humans is through mosquitoes (primarily culex species) that have acquired the virus from infected birds. A single elevated WNV result, including IgM that may persist for many months, could represent past infection with WNV or infection with another flavivirus including Dengue and St. Louis Encephalitis. Diagnosis of suspected WNV infection is confirmed by isolation of WNV or detection of WNV antigen or nucleic acid sequences in clinical samples or detection of WNV-specific IgM in blood or spinal fluid, confirmed with detection of WNV-specific neutralizing antibody in the same or a subsequent sample.

See West Nile Virus: Detection with Immunologic and RT-PCR Assays in the Infectious Disease chapter, Interpretive Information section.