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Test Code WNVSI West Nile Serum Interpretation

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Method Name

Only orderable as part of a profile. For more information see WNS / West Nile Virus Antibody, IgG and IgM, Serum.

Reporting Name

West Nile Serum Interpretation


Specimen Required


Only orderable as part of a profile. For more information see WNS / West Nile Virus Antibody, IgG and IgM, Serum.


Specimen Type

Serum

Specimen 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

Hemolysis Mild OK; Gross OK
Lipemia Mild OK; Gross reject
Icterus Mild OK; Gross reject
Other NA

Reference Values

Only orderable as part of a profile. For more information see WNS / West Nile Virus Antibody, IgG and IgM, Serum.

Day(s) and Time(s) Performed

Monday, Wednesday, Friday; 9 a.m.

Test Classification

This test has been cleared or approved by the U.S. 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.

LOINC Code Information

Test ID Test Order Name Order LOINC Value
WNVSI West Nile Serum Interpretation 69048-7

 

Result ID Test Result Name Result LOINC Value
WNVSI West Nile Serum Interpretation 69048-7

Useful For

Laboratory diagnosis of infection with West Nile virus

Interpretation

IgG:

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 drawn within approximately 7 days postinfection should be compared with a specimen drawn approximately 14 to 21 days after infection to demonstrate rising IgG antibody levels between the 2 serum specimens.

 

IgM:

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 drawn too early in the acute phase (eg, before 8 to 10 days post-infection) may be negative for IgM-specific antibodies to WNV. If WNV is suspected, a second specimen drawn approximately 14 days postinfection should be tested.

 

In the very early stages of WNV infection, IgM may be detectable in cerebrospinal fluid (CSF) before it becomes detectable in serum.