St. Louis 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 suggest current or past infection.Antibody to any of the Flavivirus group (Group B viruses) will react quite strongly with the St. Louis encephalitis viral antigen and, therefore, cannot be differentiated further. The specific virus responsible for such a titer must be deduced by the travel history of the patient, along with available medical and epidemiological data, unless the virus can be isolated.

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 performed in the same laboratory at the same time.
CPT Code(s)
Component Test Code*Component Chart NameLOINC
0050507St. Louis Encephalitis Ab, IgG, Serum10906-6
* 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.
  • St. Louis encephalitis IgG, Serum