Sign in →

Test Code HME (EHRC) Ehrlichia chaffeensis (HME) Antibody, IgG, Serum

Reporting Name

Ehrlichia Chaffeensis (HME) Ab, IgG

Useful For

As an adjunct in the diagnosis of ehrlichiosis

 

Seroepidemiological surveys of the prevalence of the infection in certain populations

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Serum


Specimen 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
Serum Refrigerated (preferred) 14 days
  Frozen  14 days

Reference Values

<1:64

Reference values apply to all ages.

Day(s) and Time(s) Performed

Monday through Friday; 9 a.m.

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

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.

Cautions

Serology for IgG may be negative during the acute phase of infection (<7 days postsymptom onset), during which time detection using targeted nucleic acid amplification testing (eg, PCR) is recommended.

 

Detectable IgG-class antibodies typically appear within 7 to 10 days postsymptom onset.

 

IgG-class antibodies may remain detectable for months to years following prior infection. Therefore, a single time point-positive titer needs to be interpreted alongside other findings to differentiate recent versus past infection.

 

Other members of the Ehrlichia genus (eg, E ewingii) may not be detected by this assay.

Clinical Reference

CDC. Tick-borne diseases of the United States: A Reference Manual for Health Care Providers. Fourth Edition, 2017

Method Description

Immunofluorescence assay technique using antigen substrate slides consisting of a cell culture infected with Ehrlichia chaffeenis.(Dawson JE, Fishbein DB, Eng TR, et al: Diagnosis of human ehrlichiosis with the indirect fluorescent antibody test: kinetics and specificity. J Infect Dis 1990;162:91-95)

Analytic Time

Same day/1 day

Specimen Retention Time

14 days

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross reject

Icterus

Mild OK; Gross reject

Other

Heat-inactivated specimen

NY State Approved

Yes

Method Name

Immunofluorescence Assay (IFA)

Forms

If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.