Indirect Immunofluorescence Assay (IFA) – IgG

Detection of IgG antibodies to Ehrlichia chaffeensis by IFA.

Fresh human serum. Minimum volume of serum required - 0.5 mL. Hyperlipemic, hemolytic or contaminated sera may yield erroneous results.

Collect blood in serum separator tubes.

Transfer an aliquot of serum to a 1.5 ml screw-top vial with O-ring (Sarstedt vial). Store specimens refrigerated up to 5 days or store frozen until shipped for testing. Ship frozen on dry or wet 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 travel to eastern, southeastern or south-central United States.

Completed requisition for Tick-borne Disease Diagnostic Testing. 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 are not accompanied by relevant patient information and travel history.

THIS TEST IS PERFORMED FOR INVESTIGATIONAL OR RESEARCH PURPOSES ONLY

Commercially prepared IFA reagents. This is a semi-quantitative test for the detection of IgG antibodies to E. chaffeensis. A four-fold or greater increase in IgG titre between two serum samples drawn 1 to 2 weeks apart and tested in parallel is considered presumptive evidence of a recent or current infection with E. chaffeensis. An IgG endpoint greater than 1:64 alone should not be relied on for an Ehrlichiosis diagnosis.

Initiation of antibiotic treatment prior to testing may result in decreased antibody production which will affect the outcome of serological testing. However, if Ehrlichiosis is suspected based on clinical symptoms, treatment should be initiated.

30 calendar days.

1. Dumler, J.S., Madigan, J.E., Pusteria, N., Bakken, J.S. 2007. Ehrlichiosis in humans: Epidemiology, clinical presentation, diagnosis and treatment. Clin. Inf. Dis. 45:S45-51.