West Nile Virus IgG, Serum




Test Mnemonic

WESTG

CPT Codes

  • 86789 - QTY (1)

LOINC ®

38997-3

Includes

  • West Nile Virus IgG

Performing Laboratory

ARUP


Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
1 mLSerumSST (Gold) RefrigeratedSeparate serum from cells ASAP or within 2 hours of collection and transfer to standard aliquot tube. Parallel testing is preferred and convalescent specimens MUST be received within 30 days from receipt of the acute specimens. Label specimens plainly as 'acute' or 'convalescent.'

Minimum Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
0.15 mL     

Stability

Environmental Condition Description
AmbientAfter separation from cells: 48 hours
RefrigeratedAfter separation from cells: 2 weeks
FrozenAfter separation from cells: 1 year (avoid repeated freeze/thaw cycles)

Days Performed

Sun, Tues, Fri

Turnaround Time

2 - 7 days

Methodology

Name Description
Semi Quantitative Enzyme Linked Immunosorbent Assay 

Reference Range

West Nile Virus IgG
Sex Age From Age To Type Range Range Unit
       1.29 IV or less: Negative - No significant level of West Nile virus IgG antibody detected. 
       1.30 - 1.49 IV: Equivocal - Questionable presence of West Nile virus IgG antibody detected. Repeat testing in 10-14 days may be helpful. 
       1.50 IV or greater: Positive - Presence of IgG antibody to West Nile virus detected, suggestive of current or past infection. 

Special Info

Parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens. Mark specimen plainly as "acute" or "convalescent." Contaminated, heat-inactivated, hemolyzed, icteric, lipemic, or turbid specimens will be rejected. This test is New York DOH approved.

Clinical Info

This test is intended to be used as a semi-quantitative means of detecting West Nile virus-specific IgG in serum specimens in which there is a clinical suspicion of West Nile virus infection. This test should not be used solely for quantitative purpose, 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. Seroconversion between acute and convalescent sera is considered strong evidence of current or recent infection. The best evidence for infection is a significant change on two appropriately timed specimens, where both tests are done in the same laboratory at the same time.