Ehrlichia chaffeensis – Serology

Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

Specimen Collection and Handling

Specimen Requirements

Test Requested Required Requisition(s) Specimen Type Minimum Volume Collection Kit

Ehrlichia chaffeensis serology, or HME serology, or Human monocytic Ehrlichiosis serology, or Ehrlichia serology


1.0 ml

Blood, clotted - vacutainer tubes (SST)

Ehrlichia chaffeensis serology, or HME serology, or Human monocytic Ehrlichiosis serology, or Ehrlichia serology


5.0 ml

Blood, clotted - vacutainer tubes (SST)

Submission and Collection Notes


Complete the following fields of the General Test Requisition Form if diagnostic testing is required:

  • Clinical symptoms
  • Exposure (e.g. tick bite)
  • Travel history
  • Onset date

Clinical information and travel history is required prior to testing E. chaffeensis serology.


PCR testing is also available upon request. Contact the laboratory prior to submission if you require PCR testing.

Timing of Specimen Collection

An acute (collected early after the onset of symptoms) and a convalescent (collected 2-3 weeks later) may be required for laboratory diagnosis.


Haemolysed, icteric, lipemic or microbially contaminated sera or plasma are not recommended for testing.

Storage and Transport

Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay.

Special Instructions

Centrifuge if using SST. Label specimens with at least two identifiers; place it in biohazard bag and seal. Specimens should be stored at 2-8°C following collection and shipped to PHOL on ice packs.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Ehrlichia chaffeensis IgG is a Referred Out Test. Samples are sent to the National Microbiology Lab (NML) in Winnipeg.

Turnaround time is up to 42 days from receipt by PHO Laboratory.

Test Methods

Ehrlichia chaffeensis IgG test is performed using Indirect Immunofluorescence Assay (IFA). 


Results are reported to the ordering physician or health care provider as indicated on the requisition.

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Laboratory Services

Updated 20 July 2020