ARUP's Laboratory Test Directory
| 0050507: St. Louis Encephalitis Antibody, IgG by IFA, Serum |
| Test Mnemonic: ST LOUIS | |
|
Methodology: Indirect Fluorescent Antibody
Performed: Tue, Fri Reported: 1-5 days |
| Specimen Required: | |
|
Collect: One 4 mL SST.
Transport: 1 mL serum at 2-8°C. (Min: 0.5 mL) Submit specimen in an ARUP Standard Transport Tube. Pediatric Collection/Transport: 0.15 mL serum at 2-8°C. Remarks: Separate serum from cells ASAP. Acute and convalescent specimens must be labeled as such parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens. Please mark specimen plainly as "acute" or "convalescent." Unacceptable Conditions: Severely lipemic, hemolyzed, or contaminated specimens. Stability: After separation from cells: Ambient: 2 days; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles) |
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| 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.
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| Note: | |
| 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): | |
| 86653 |