Ordering Recommendation

Diagnose infection from Ehrlichia chaffeensis.

New York DOH Approval Status

This test is New York state approved.

Specimen Required

Patient Preparation

Serum Separator Tube.

Specimen Preparation

Separate from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to an ARUP standard transport tube. (Min: 0.4 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)


Semi-Quantitative Indirect Fluorescent Antibody (IFA)


Tue, Fri


1-5 days

Reference Interval

Test Number
Reference Interval
  Ehrlichia chaffeensis Antibody, IgG Less than 1:64
  Ehrlichia chaffeensis Antibody, IgM Less than 1:16

Interpretive Data

Component Interpretation
Ehrlichia chaffeensis Antibody, IgG by IFA < 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.
≥1:256  Positive-Presence of IgG antibody to Ehrlichia chaffeensis detected, suggestive of current or past infection.
Ehrlichia chaffeensis Antibody, IgM by IFA < 1:16  Negative-No significant level of Ehrlichia chaffeensis IgM antibody detected.
≥ 1:16  Positive-Presence of IgM antibody to Ehrlichia chaffeensis detected, suggestive of current or recent infection.

Compliance Category

Laboratory Developed Test (LDT)


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.

Hotline History


CPT Codes

86666 x2


Component Test Code* Component Chart Name LOINC
0051003 Ehrlichia chaffeensis Antibody, IgM 48850-2
0051004 Ehrlichia chaffeensis Antibody, IgG 47405-6
* 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.


  • E. chaffeensis antibodies
  • E. Chaffeensis IgG, IgM Ab
  • Ehrlichiosis IFA test
Ehrlichia chaffeensis Antibodies, IgG & IgM by IFA