Ixodes scapularis, fighting back, a clinician's guide to lyme disease testing in Manitoba: A critical appraisal of current and proposed testing methods
Background: Lyme disease, a tick borne illness caused by Borrelia burgdorferi, is an increas-ingly prevalent infectious disease in Canada. In 2009, there were 128 cases of Lyme disease re-ported across Canada. In 2015, there were over 700 cases, 35 of those cases in Manitoba. Due to rising temperatures the geographic range of I. scapularis, the primary vector of Lyme disease in Manitoba, is enlarging. This will most likely cause an increase in incidence of human infection. As incidence increases it is important to have a full understanding of Lyme disease presentation, testing and treatment. Much of the current research of Lyme disease focuses on testing. Testing for Lyme disease provides useful assistance in diagnosis, however weaknesses exist including insensitivity to early disease and inability to differentiate from active infection or treated infec-tion. This paper will provide a quantitative critical appraisal of current and proposed research for Lyme disease testing. Methods: A comprehensive Pub Med and Google Scholar database search for “Lyme disease” and “testing” in the last 10 years was conducted. Articles met inclusion criteria if they evaluated any of the testing methods recommended by Infectious Disease Society of America or new pro-posed methods including: ELISA/whole cell sonicate immunosorbent assay, C6, PCR, iPCR, Western blot, and V1sE. Testing methods had to evaluate serum samples collected from patients with known Lyme disease by symptomatology and confirmatory testing. These articles were re-viewed for sensitivity and specificity of testing methods. Results: In early Lyme disease, standard 2 tier testing was 38-40% sensitive. iPCR hybrid anti-gen was 55% sensitive. First tier testing C6 ELISA was most sensitive at 64.6%. In early disseminated Lyme disease, standard 2 tier testing sensitivity increased to 80-88%. PCR and culture decreased to 29% sensitivity. 2 tier ELISA algorithm provided 100% sensitivity and single C6 ELISA provided 90% sensitivity. In late disseminated Lyme disease, standard 2 tier testing was 92-100% sensitive. Single C6 ELISA was 98.2 % sensitive. iPCR was 92% sensitive and 2 tier ELISA was 100% sensitive. Convalescent samples of serum from patients treated with antibiotics continued to have sensitivi-ty of 87-100% in C6 ELISA. Specificity of standard 2 tier testing, single C6 ELISA, iPCR and 2 tier ELISA testing was simi-lar ranging from 97-100%. Specialty labs A and B in the U.S. had 37.8% and 42.5% sensitivity with standard 2 tier testing. Specialty lab B sensitivity changed to 70. 3% when using in-house criteria for interpretation of western blot and specificity decreased from 100% to 72.5%. Conclusion: Lyme disease testing methods continue to be insensitive to early Lyme disease. Newer methods such as iPCR hybrid antigen provided similar sensitivity to early Lyme disease as current recommend methods. Standard 2 tier testing to disseminated Lyme disease is sensitive and specific. Proposed 2 tier ELISA, first tier C6 ELISA and new iPCR hybrid antigen provide similar sensitivity and sensitivity to disseminated Lyme disease. These methods could potentially be used as alternatives to Western blot to avoid inter-laboratory subjectivity.