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HelpTest Code Billings Clinic: 7147 Mayo: WNS West Nile Virus Antibody, IgG and IgM, Serum
Reporting Name
West Nile Virus Ab, IgG and IgM, SPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Useful For
Laboratory diagnosis of infection with West Nile virus using serum specimens
Method Name
Enzyme-Linked Immunosorbent Assay (ELISA)
Specimen Required
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Type
SerumSpecimen Minimum Volume
0.4 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 14 days | |
| Frozen | 14 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
| Heat Inactivated specimen | Reject |
Reference Values
IgG: negative
IgM: negative
Reference values apply to all ages.
Interpretation
The presence of IgG-class antibodies to West Nile virus (WNV) in serum indicates infection with WNV at some time in the past. By 3 weeks postinfection, virtually all infected persons should have developed IgG antibodies to WNV. If acute-phase infection is suspected, serum specimens collected within approximately 7 days postinfection should be compared with a specimen collected approximately 14 to 21 days postinfection to demonstrate rising IgG antibody levels between the 2 serum specimens.
Presence of specific IgM-class antibodies in a serum specimen is consistent with acute-phase infection with WNV. By the 8th day of illness, most infected persons will have detectable serum IgM antibody to WNV; in most cases it will be detectable for at least 1 to 2 months following disease resolution and, in some cases, will be detectable for 12 months or longer.
The absence of IgM antibodies to WNV is consistent with lack of acute-phase infection with this virus. Specimens collected too early in the acute phase (eg, before 8-10 days postinfection) may be negative for IgM-specific antibodies to WNV. If WNV is suspected, a second specimen collected approximately 14 days postinfection should be tested.
In the very early stages of WNV infection, IgM may be detectable in cerebrospinal fluid before it becomes detectable in serum.
Day(s) Performed
Monday, Wednesday, Friday
Report Available
Same day/1 to 4 daysTest Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
IgG-86789
IgM-86788
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| WNS | West Nile Virus Ab, IgG and IgM, S | 94854-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| WNGS | West Nile Virus Ab, IgG, S | 29566-7 |
| WNMS | West Nile Virus Ab, IgM, S | 29567-5 |
| WNVSI | West Nile Serum Interpretation | 69048-7 |
Forms
If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| WNGS | West Nile Virus Ab, IgG, S | No | Yes |
| WNMS | West Nile Virus Ab, IgM, S | No | Yes |
| WNVSI | West Nile Serum Interpretation | No | Yes |