Ehrlichia chaffeensis (IgG, IgM), with Reflex to Titers

HGE, Human Granulocytic Ehrlichiosis, HME, Human Monocytic Ehrlichiosis, Ehrlichia Chaffeensis Antibodies, IgG and IgM, E. Chaffeensis Ab

Test Codes

EPIC: LAB1232287, Beaker: Echafab, Quest: 16197

Department

Send Outs

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube. (Minimum: 5.0 mL)
Also acceptable: One plain Red-top tube.

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells within two hours of collection. Transfer serum to a plastic transport tube and maintain at room temperature (20-26°C or 68-78.8°F) prior to transport.

Preparation for Courier Transport

Transport: 1.0 mL serum, at room temperature (20-26°C or 68-78.8°F). (Minimum: 0.2 mL)

Rejection Criteria

• Hemolyzed specimens.
• Severely lipemic specimens.
• Specimens not collected and processed as indicated.

In-Lab Processing

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells within two hours of collection. Transfer serum to a plastic transport tube and maintain at room temperature (20-26°C or 68-78.8°F) prior to transport.

Transport: 1.0 mL serum, at room temperature (20-26°C or 68-78.8°F). (Minimum: 0.2 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 7 hours
Refrigerated (2-8°C or 36-46°F): 14 days
Frozen (-20°C/-4°F or below): 30 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Quest Diagnostics, Wood Dale, IL.

Performed

Tuesday, Thursday, Saturday.
Results available in 3-4 days.

Reference Range

E. chaffeensis Ab (IgG), Screen:  Not detected.
E. chaffeensis Ab (IgM), Screen:  Not detected.
E. chaffeensis Ab (IgG), Titer:   <1:64 titer
E. chaffeensis Ab (IgM), Titer:  <1:20 titer

Test Methodology

Immunofluorescence Assay (IFA)

Clinical Utility

Ehrlichia chaffeensis (IgG, IgM) with Reflex to Titers – This test is for the detection of IgG and IgM antibodies against Ehrlichia chaffeensis to aid in the diagnosis of Ehrlichiosis (human monocytic ehrlichiosis). Ehrlichiosis is a tickborne disease caused by transmission of the bacteria via the bite of an infected tick. It is most common in the eastern to southeastern and south-central United States.

Testing for E. chaffeensis is based on a clinical evaluation and risk of tick exposure with consideration to the geographic region. Symptoms may be nonspecific, including headache, fever/chills, malaise, myalgia, gastrointestinal symptoms, and rash. Infection can have similarities with other tickborne illnesses with overlapping vectors, geographic endemicity, and similar clinical signs and symptoms, including Anaplasma spp, Borrelia burgdorferi (Lyme disease) and Babesia microti.

Negative results can occur early in infection. Nucleic acid amplification tests are the preferred method for diagnosis during acute infection. Seroconversion or a four-fold increase between acute and convalescent sera can be used to support a diagnosis. The presence of IgG alone may indicate past infection, and IgM may persist for many months after infection has resolved. Antibody levels may remain elevated for several years after acute illness. Cross-reactivity between related organisms Anaplasma and Ehrlichia spp, can occur. Therefore, interpretation of serologic results is done in the context of pertinent clinical picture, including timing from symptom onset.

Reference

1. Tickborne Diseases of the United States. A Reference Manual for Healthcare Providers, Sixth Edition, 2022. Centers for Disease Control and Prevention.
2. Clinical Testing and Diagnosis for Ehrlichiosis Centers for Disease Control and Prevention. Last updated May 15, 2024. https://www.cdc.gov/ehrlichiosis/hcp/diagnosis-testing/index.html.
3. Miller, MJ. Et al. Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2024 Update by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM). Clin Infect Dis. 2024 Mar 5: ciae104.doi: 10.1093/cid/ciae104.
4. Biggs, HM, et al. Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever and Other Spotted Fever Group Rickettsioses, Ehrlichioses, and Anaplasmosis - United States. MMWR Recomm Rep. 2016 May 13;65(2):1-44.

Test Resources:

Algorithm
Serological Test Selection for the Differential Diagnosis of Tick-borne Diseases Based on Geographic Origin and Symptoms of Infection

Topic Brief
Tick-borne Disease: Laboratory Support of Diagnosis and Management

CPT Codes

86666 x2

Contacts

Last Updated

1/28/2026