0050239
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West Nile Virus Antibody, IgM by ELISA, CSF

WNIL IGM
Example Reports
Negative
Positive

Ordering Recommendation

Preferred test for diagnosing West Nile encephalitis.

New York DOH Approval Status

Testing is not New York state approved. Specimens from New York clients will be sent out to a New York state-approved laboratory.

Specimen Required

Patient Preparation
Collect

CSF.

Specimen Preparation

Transfer 2 mL CSF to an ARUP Standard Transport Tube. (Min: 0.3 mL)
New York State Clients: 2 mL (Min: 0.7 mL)

Storage/Transport Temperature

Refrigerated.
New York State Clients: Frozen

Unacceptable Conditions

Bacterially contaminated, heat-inactivated, hemolyzed or xanthochromic specimens.

Remarks
Stability

Ambient: 8 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)
New York State Clients: Ambient: 4 days; Refrigerated: 1 week; Frozen: 1 month

Methodology

Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Performed

Sun, Tue, Fri

Reported

1-6 days

Reference Interval

0.89 IV or less Negative - No significant level of West Nile virus IgM antibody detected.
0.90-1.10 IV Equivocal - Questionable presence of West Nile virus IgM antibody detected.  Repeat testing in 10-14 days may be helpful.
1.11 IV or greater Positive - Presence of IgM antibody to West Nile virus detected, suggestive of current or recent infection.

Interpretive Data

This test is intended to be used as a semi-quantitative means of detecting West Nile virus-specific IgM in CSF specimens in which there is a clinical suspicion of West Nile virus infection.  This test should not be used solely for quantitative purposes, nor should the results be used without correlation to clinical history or other data.  Because other members of the Flaviviridae family, such as St. Louis encephalitis virus, show extensive cross-reactivity with West Nile virus, serologic testing specific for these species should be considered.

The detection of antibodies to West Nile virus in cerebrospinal fluid may indicate central nervous system infection.  However, consideration must be given to possible contamination by blood or transfer of serum antibodies across the blood-brain barrier.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Compliance Category

Laboratory Developed Test (LDT)

Note

Hotline History

N/A

CPT Codes

86788

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Components

Component Test Code* Component Chart Name LOINC
0050239 West Nile Virus Antibody IgM CSF 39573-1
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.

Aliases

  • Arbovirus
  • Flavivirus
  • WNV IgM CSF
West Nile Virus Antibody, IgM by ELISA, CSF