West Nile Virus Antibody, IgM by ELISA, CSF
Ordering Recommendation

Preferred test for diagnosing West Nile encephalitis.

Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Sun, Tue, Fri
1-6 days
New York DOH Approval Status
Specimens from New York clients will be sent out to a New York DOH approved laboratory, if possible.
Submit With Order
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Specimen Preparation
Transfer 2 mL CSF to an ARUP Standard Transport Tube. (Min: 0.15 mL)  
Storage/Transport Temperature
Unacceptable Conditions
Contaminated, heat-inactivated, or hemolyzed specimens.  
Ambient: 8 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)  
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.

Compliance Statement B: For laboratory developed tests not using a RUO kit, and for FDA approved, cleared or 510(k) exempt assays with alterations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.
CPT Code(s)
Component Test Code*Component Chart NameLOINC
0050239West Nile Virus Antibody IgM CSF39573-1
* 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.
  • Arbovirus
  • Flavivirus