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Epic Test Code LAB794 Ehrlichia chaffeensis (HME) Antibody, IgG, Serum

Additional Codes

MML Code: EHRC

 

Acute Tick-Borne Disease Testing Algorithm with Bassett Test Codes

NY State Approved

Yes

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Reporting Name

Ehrlichia Chaffeensis (HME) Ab, IgG

Method Name

Immunofluorescence Assay (IFA)

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 14 days
  Frozen  14 days


Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.


Bassett Healthcare Network Clinical Laboratories Note:

Blood Tube Draw Volume
Min 50% draw volume  

  • 50% of the tube fill volume is required for proper blood to additive ratio.

Specimen Type

Serum

Specimen Minimum Volume

0.4 mL

Reference Values

<1:64

Reference values apply to all ages.

Report Available

Same day/1 to 3 days

Day(s) Performed

Monday through Friday

CPT Code Information

86666

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject
Heat-inactivated specimen Reject

Useful 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 result (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 result although antibody levels decline significantly during the year following infection.

Cautions

Serology results for IgG may be negative during the acute phase of infection (<7 days post-symptom onset), during which time detection using targeted nucleic acid amplification testing (eg, polymerase chain reaction) is recommended.

 

Detectable IgG-class antibodies typically appear within 7 to 10 days post-symptom 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, Ehrlichia ewingii) may not be detected by this assay.

Specimen Retention Time

14 days

Testing Algorithm

For more information see Acute Tick-Borne Disease Testing Algorithm

Forms

If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.