Ehrlichia chaffeensis Antibody, IgM by IFA
Ordering Recommendation
Most useful to detect antibodies during acute phase of disease; recommend concurrent testing with IgG E. chaffeensis. PCR testing is preferred; refer to Tick-Borne Disease Panel by PCR, Blood (2008670) or Ehrlichia and Anaplasma Species by Real-Time PCR (2007862).
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
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
< 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.  
Interpretive Data
While the presence of IgM antibodies suggests current or recent infection, low levels of IgM antibodies may occasionally persist for more than 12 months post-infection. A single IgM result should be interpreted with caution.

Compliance Statement B: This test was developed and its performance characteristics determined by ARUP Laboratories. The U.S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.
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)
Component Test Code*Component Chart NameLOINC
0051003Ehrlichia chaffeensis Antibody, IgM48850-2
* 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
  • HME (Human Monocytic Ehrlichiosis)
  • Tick Borne Diseases