Test Catalog



Also known as: W132, WNV IgG
Orderable Code: W132
Test Contains (LOINC): West Nile Virus IgG (38997-3)
Sample Type: Serum
Preferred Container: Serum Separator Tube (SST)
Alternate Container: Plain (Red Top) Tube
Sample Volume: 1.0 mL
Minimal Sample Volume: 0.5 mL (does not allow for repeat testing)
Handling Instructions:
Centrifuge sample and separate serum from cells ASAP. Aliquot and freeze. Acute and convalescent specimens must be labeled appropriately; parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens. Please mark specimen plainly as ‘acute’ or ‘convalescent’.
Client Transport Temperature: Frozen
Specimen Stability: Ambient: 2 Days; Refrigerated: 19 Days; Frozen: 1 Month
Unsuitable Specimen: Hemolyzed, grossly lipemic, contaminated, heat-inactivated or plasma specimens.
Frequency: Tuesday, Thursday
Expected Turn Around: 4 – 6 Days
Responsible Dept: Reference Lab
Referral Lab: SRL
Referral Lab Code: W132
CPT: 86789
Methodology: Enzyme-Linked Immunosorbent Assay (ELISA)
West Nile Virus (WNV) is a zoonotic arbovirus, transmitted through complex life cycles involving a vertebrate (e.g., birds) and an arthropod (e.g., mosquitoes). Humans and domestic animals can develop clinical illness but are usually “dead-end” hosts because they do not produce significant viremia. Infection is most often not transmitted from person to person. Arbovirus infections can be prevented in two major ways: personal protective measures to reduce contact with mosquitoes and public health measures to reduce the population of infected mosquitoes in the environment. Most people who are infected with WNV will not have any type of illness. Roughly 20% of people who become infected will develop West Nile fever: mild symptoms including fever, headache, and body aches, occasionally with a skin rash on the trunk of the body and swollen lymph glands. Symptoms of mild disease will generally last a few days. About 1 in 150 of WNV infections (< 1%) will result in meningitis or encephalitis. Fatality rates among patients hospitalized during recent outbreaks have ranged from 4% to 14%. The most important risk factor for death is advanced aged. Patients older than 70 years of age are at particularly high risk.
The presence of IgM antibodies in serum is suggestive of current or recent WNV infection. By the eighth day of infection, a large majority of infected persons will have detectable serum IgM antibody to WNV; in most cases it will be detectable for at least 1-2 months after illness onset, and in some cases it will be detectable for 500 days or longer. Presence of IgG antibody is suggestive of recent or past WNV infection. By three weeks post-infection (and often earlier), virtually all infected persons should demonstrate serum IgG antibody to WNV for 500 days or longer.
Compliance Statement: FDA cleared or approved assay