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For hours, walk-ins and appointments.Synonyms
- Flavivirus
- Mosquito-borne
- Vectorborne
- West Nile Virus, IgG and IgM
- West Nile Virus, Serology
- WNV Antibody
Expected Turnaround Time
1 - 4 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
Specimen Requirements
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
Red-top tube or gel-barrier tube
Storage Instructions
Room temperature
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 16 days |
Refrigerated | 16 days |
Frozen | 16 days |
Freeze/thaw cycles | Stable x4 |
Causes for Rejection
Gross contamination; severe hemolysis; icteric serum; lipemic serum; quantity not sufficient for analysis
Test Details
Use
This test is indicated for use as an aid to the diagnosis of West Nile virus encephalitis. WNV IgM antibodies typically appear three to eight days after illness onset and persist 30 to 90 days (but can persist up to 500 days). WNV IgG antibodies appear shortly after IgM antibodies and persist greater than 500 days. Due to cross-reactivity with other flaviviruses, confirmation by neutralizing antibody assay may be recommended.
Limitations
The performance of this assay has not been established for screening the general population. Testing should only be performed on patients with clinical symptoms consistent with WNV encephalitis. Serological cross-reactivity across the flavivirus group is common (i.e., between Dengue virus, Japanese encephalitis virus, St. Louis encephalitis virus, yellow fever virus and others).
Methodology
Enzyme immunoassay (EIA)
Reference Interval
Negative
References
Tardei G, Ruta S, Chitu V, Tardei G, Ruta S, Chitu V, Rossi C, Tsai TF, Cernescu C. Evaluation of immunoglobulin M (IgM) and IgG enzyme immunoassays in serologic diagnosis of West Nile virus infection. J Clin Microbiol. 2000 Jun;38(6):2232-2239.10834982
West Nile Virus: Diagnostic Testing. Centers for Disease Control and Prevention (CDC) website: https://www.cdc.gov/westnile/healthcareproviders/healthCareProviders-Diagnostic.html. Updated April 2023. Accessed October 2023.
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 138842 | West Nile Virus Antibody,Serum | 94854-7 | 139037 | West Nile Virus, IgG | 29566-7 | |
| 138842 | West Nile Virus Antibody,Serum | 94854-7 | 139038 | West Nile Virus, IgM | 29567-5 |
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