Resources

West Nile Virus Antibodies (IgG, IgM), CSF

Test Code
WNILC


Alias/See Also
36597


CPT Codes
86788, 86789

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


Minimum Volume
0.7 mL


Transport Temperature
Refrigerated (cold packs)


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


Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis • Grossly icteric


Methodology
Enzyme Immunoassay (EIA)

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


Reference Range
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


Clinical Significance
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.


Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153


Last Updated: June 22, 2023


The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.