Molecular Detection

Molecular detection of Ehrlichia chaffeensis in clinical specimens.

Whole blood specimens are recommended. Cerebrospinal fluid (CSF) from patients whose clinical condition suggests meningitis are acceptable. Minimum required volumes are as follows:

Whole blood – 0.5 mL.
CSF – 0.5 mL

Collect blood in EDTA tubes. Avoid heparin. Do not centrifuge. Aseptically sample into sterile, leak-proof container made of freeze-thaw and shatter-resistant plastic, without additives.

Store specimens refrigerated up to 5 days and ship with freezer packs. If > 5 days, store at – 20 °C and ship on dry ice.

Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult either Part 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.

Appropriate clinical symptoms with known exposure to Amblyomma americanum (Lone Star) tick in Canada OR relevent travel history. The symptoms of infection with Ehrlichia chaffeensis usually develop 1-2 weeks after being bitten by an infected tick. Symptoms may include fever, headache, chills, malaise, myalgia, nausea / vomiting / diarrhea, confusion, conjunctival injection and rash.

Completed Requisition for Molecular Testing for Selected Zoonotic Agents. If possible, include the clinical history and lab results performed at local or provincial laboratories.

Specimens may be subject to rejection if they are not the appropriate sample type, have insufficient volume, or not accompanied by relevant patient information and travel history. This test is performed for investigational purposes.

Testing is performed, in whole or in part, using a lab-developed test which has not been fully validated/verified.

Extracted DNA is screened by real-time PCR assay specific for E. chaffeensis. Samples that have screened positive are subject to confirmatory testing.

Initiation of antibiotic treatment prior to testing may result in decreased bacterial genome which will affect the outcome of PCR testing.

21 calendar days.

1. Loftis, A., D., Massung, R. F., Levin, M., L. 2003. Quantitative real-time PCR assay for detection of Ehrlichia chaffeensis. J. Clin. Microbiol. 41(8):3870-3872.
2. Standaert, S.M., Yu, T., Scott, M.A., et al. 2000. Primary Isolation of Ehrlichia chaffeensis from patients with febrile illnesses: Clinical and molecular characteristics. J. Inf. Dis. 181:1082-1088.