ARUP's Laboratory Test Directory

0051004: Ehrlichia chaffeensis Antibody, IgG by IFA

Test Mnemonic: E CH G
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, contaminated, or hemolyzed specimens.

Stability: After separation from cells: Ambient: 2 days; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)

Reference Interval:
< 1:64  Negative-No significant level of Ehrlichia chaffeensis IgG antibody detected.
1:64-1:128  Equivocal-Questionable presence of Ehrlichia chaffeensis IgG antibody detected.  Repeat testing in 10-14 days may be helpful.
³1:256  Positive-Presence of IgG antibody to Ehrlichia chaffeensis detected, suggestive of current or past infection.

Interpretive Data:
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.

Please refer to Statement A in the Compliance Statements section in the front of the Laboratory Test Directory.



Note:
Human ehrlichiosis is a tick-borne disease caused by rickettsial-like agents. Two forms, human monocytic ehrlichiosis (HME) and human granulocytic ehrlichiosis (HGE), have been described. HME is often referred to as "spotless" or rashless Rocky Mountain spotted fever, and has been reported in various regions of the United States. The causative agent of HME has been identified as Ehrlichia chaffeensis. Infected individuals produce specific antibodies to Ehrlichia chaffeensis which can be detected by an immunofluorescent antibody (IFA) test.

CPT Code(s):
86666