Test ID: EHRC Ehrlichia chaffeensis (HME) Antibody, IgG, Serum
Reporting Name
Ehrlichia Chaffeensis (HME) Ab, IgGUseful For
An adjunct in the diagnosis of ehrlichiosis
Seroepidemiological surveys of the prevalence of the infection in certain populations
Clinical Information
Ehrlichia chaffeensis is an intracellular rickettsia-like bacterium that preferentially infects monocytes and is sequestered in parasitophorous vacuoles referred to as morulae. Infections with E chaffeensis are also referred to as human monocytotropic ehrlichiosis (HME). E chaffeensis is transmitted by Amblyomma species ticks, which are found throughout the southeastern and south central United States.
Many cases of HME are subclinical or mild, however, the infection can be severe and life-threatening, particularly in immunosuppressed individuals. Reported mortality rates range from 2% to 3%. Fever, fatigue, malaise, headache, and other "flu-like" symptoms occur most commonly. Leukopenia, thrombocytopenia, and elevated hepatic transaminases are frequent laboratory findings.
Interpretation
A positive immunofluorescence assay (titer ≥1:64) suggests current or previous infection. In general, the higher the titer, the more likely the patient has an active infection. Four-fold rises in titer also indicate active infection.
Previous episodes of ehrlichiosis may produce a positive serology although antibody levels decline significantly during the year following infection.
Testing Algorithm
See Acute Tick-Borne Disease Testing Algorithm in Special Instructions.
Analytic Time
Same day/1 dayDay(s) and Time(s) Performed
Monday through Friday; 9 a.m.
Clinical Reference
Centers for Disease Control and Prevention (CDC), Division of Vector-Borne Diseases: Tickborne diseases of the United States: A Reference manual for health care providers. 4th ed. CDC; 2017
Method Name
Immunofluorescence Assay (IFA)
Specimen Type
SerumSpecimen Required
Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Specimen Volume: 0.5 mL
Specimen Minimum Volume
0.15 mL
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum | Refrigerated (preferred) | 14 days | |
Frozen | 14 days |
Special Instructions
Reference Values
<1:64
Reference values apply to all ages.
Test Classification
This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
86666
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
EHRC | Ehrlichia Chaffeensis (HME) Ab, IgG | 47405-6 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
81478 | Ehrlichia Chaffeensis (HME) Ab, IgG | 47405-6 |
Forms
If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.
mml-CNS-Infections, mml-Pediatric