Update on Lyme disease diagnostic approaches and protocols in Canada: Overview of existing testing strategies and limitations.

objectiveTo provide an update on the state of Lyme disease diagnostic approaches and protocols across Canada, as well as guidance for family physicians regarding the complexities of available tests. QUALITY OF EVIDENCE: Guidelines from the Public Health Agency of Canada, the Association of Medical Microbiology and Infectious Disease Canada, the Infectious Diseases Society of America, and the European Society of Clinical Microbiology and Infectious Diseases were reviewed and summarized, as well as websites of provincial reference laboratories. Evidence levels ranged from I to III, with Grading of Recommendations Assessment, Development and Evaluation ratings ranging from moderate to low quality. MAIN MESSAGE: Lyme disease incidence is increasing in Canada, but diagnosis can be complicated by vague presenting symptoms, heterogeneous quality of online resources available to patients and family physicians, and non-standardized, non-guideline-based tests available from private, for-profit laboratories. Early recognition is primarily clinical, based on the characteristic erythema migrans rash and exposure to Lyme-endemic areas. While standard 2-tiered serologic testing was previously the mainstay of laboratory-based Lyme disease diagnosis in Canada, several reference laboratories have since transitioned to modified 2-tiered testing, with increased sensitivity in early disease detection and shortened turnaround time. Overall, diagnostic approaches vary across Canadian provinces and territories due to differing baseline Lyme disease incidence. Tests available from private laboratories are unreliable due to high false-positive rates and lack of proven clinical relevance within peer-reviewed studies.

conclusionTests and guidance available from public health reference laboratories across Canada are well aligned with international and Canadian guidelines. Diagnosis is primarily clinical in early disease and based on serologic testing in later disease. Polymerase chain reaction is less reliable outside of certain clinical specimens such as erythema migrans biopsy and synovial fluid. Family physicians should be aware of non-evidence-based assays available to patients from private laboratories in the United States and Europe.