Western Equine Encephalitis Antibody, IgG by IFA, Serum (INACTIVE as of 10/30/14)
Ordering Recommendation
Semi-Quantitative Indirect Fluorescent Antibody
Tue, Fri
1-5 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Serum separator tube. 
Specimen Preparation
Separate serum from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to an ARUP Standard Transport Tube. (Min: 0.05 mL) Parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens. Mark specimens plainly as acute or convalescent. 
Storage/Transport Temperature
Unacceptable Conditions
Contaminated, hemolyzed, or severely lipemic specimens. 
After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles) 
Reference Interval
Less than 1:16
Interpretive Data
A positive result for IgG may indicate current or past infection. Eastern equine encephalitis and western equine encephalitis viruses are both related and will show cross-reactivity. Initial infection by one of these viruses will show a specific rise in titer which is higher than titers against any other viruses of the group. A subsequent infection by another virus within this group, however, will boost the titer against the initial infecting virus (anamnestic response) and make a specific diagnosis difficult.

Serum specimens drawn within the first two weeks after onset are variably negative for IgG antibody and should not be used to exclude the diagnosis of arboviral disease.  Seroconversion between acute and convalescent sera is considered strong evidence of recent infection.  The best evidence for infection is a significant change (fourfold difference in titer) on two appropriately timed specimens, where both tests are done in the same laboratory at the same time.
CPT Code(s)
Component Test Code*Component Chart NameLOINC
0050514Western Equine Enceph Ab, IgG, Serum6957-5
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • Arbovirus IgG Serology
  • Encephalitis IgG Antibodies
  • WEE IgG
  • Western Equine Encephalitis IgG