2808      West Nile Antibody, IgG
Specimen:
  Collect: One 7.5 mL SST  
  Submit: 1 mL (Min:0.5 mL) Serum. Submit Refrigerated. Submit in a Standard Transport Tube.  
  Special Handling: Allow specimen to clot completely at room temperature
Avoid Repeated Freeze/Thaw Cycles
Separate from cells ASAP 
  Rejection Criteria: Grossly Hemolyzed Samples
Grossly Lipemic Samples 
  Stability: Ambient: 8 Hour(s); Refrigerated: 2 Day(s); Frozen: 1 Month(s); Incubated: Unacceptable 
Methodology: Enzyme-Linked ImmunoSorbent Assay (ELISA) 
Performed: Tuesday, Thursday 
Reported: 2-5 Day(s) 
CPT Codes:
86789 - West Nile Ab, IgG
Interpretive Data:

West Nile IgG Reference Range:
<1.30 NEGATIVE
1.30-1.50 EQUIVOCAL (Suggest repeat testing in 2 weeks)
>1.50 POSITIVE

This test is intended to be used as a semi-quantitative means of detecting West Nile virus-specific IgG and IgM in serum samples 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, presumptive positive results should be confirmed using tests such as the plaque reduction neutralization test.

IgG assay cross-reactivity has been noted with some specimens containing antibody to CMV and bunyavirus, e.g., LaCrosse virus.