Western Equine Encephalitis Antibody, IgG by IFA, Serum
Semi-Quantitative Indirect Fluorescent Antibody
New York DOH Approval Status
This test is New York DOH approved.
- 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)
Less than 1:16
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.
|Component Test Code*||Component Chart Name|
|0050514||Western Equine Enceph Ab, IgG, Serum|