title: Comparison between available serologic tests for detecting antibodies against Anaplasma phagocytophilum and Borrelia burgdorferi in horses in Canada.
abstract: To investigate the agreement between available serologic tests for the detection of antibodies against Anaplasma phagocytophilum and Borrelia burgdorferi, 50 serum samples from horses of unknown clinical status and at low risk for infection were tested. In addition to a point-of-care enzyme-linked immunosorbent assay (pocELISA), the evaluated tests included 2 indirect fluorescent antibody tests (IFATs) for antibodies against A. phagocytophilum and an IFAT, an ELISA confirmed with Western blot, and the Lyme multiplex assay for antibodies against B. burgdorferi. For each pair-wise comparison between serologic tests, the difference in the proportion of seropositive results as well as kappa and the prevalence-adjusted, bias-adjusted kappa were calculated. The proportion of seropositive results differed significantly in each pairwise comparison of tests for detection of antibodies against A. phagocytophilum, and between the pocELISA and IFAT as well as between the pocELISA and Lyme multiplex assay for detection of antibodies against B. burgdorferi. Agreement based on kappa varied from poor to fair while agreement was improved when evaluating prevalence-adjusted, bias-adjusted kappa. Lack of agreement may be explained by differences in methodology between the evaluated tests, cross-reactivity or false-positive and false-negative tests. In addition to the limitations of serologic test interpretation in the absence of clinical disease, this data suggest that screening of horses for exposure to tick-borne diseases in nonendemic areas may not be warranted.
authors.affiliation: Departments of Large Animal Clinical Sciences (Schvartz, Epp, Lohmann), University of Saskatchewan, Saskatoon, Saskatchewan, CanadaVeterinary Pathology (Burgess), University of Saskatchewan, Saskatoon, Saskatchewan, CanadaWestern College of Veterinary Medicine, and the Department of Biology (Chilton), University of Saskatchewan, Saskatoon, Saskatchewan, Canada giliun@gmail.com.
authors.forename: Gili
authors.initials: G
authors.lastname: Schvartz
authors.affiliation: Departments of Large Animal Clinical Sciences (Schvartz, Epp, Lohmann), University of Saskatchewan, Saskatoon, Saskatchewan, CanadaVeterinary Pathology (Burgess), University of Saskatchewan, Saskatoon, Saskatchewan, CanadaWestern College of Veterinary Medicine, and the Department of Biology (Chilton), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Tasha
authors.initials: T
authors.lastname: Epp
authors.affiliation: Departments of Large Animal Clinical Sciences (Schvartz, Epp, Lohmann), University of Saskatchewan, Saskatoon, Saskatchewan, CanadaVeterinary Pathology (Burgess), University of Saskatchewan, Saskatoon, Saskatchewan, CanadaWestern College of Veterinary Medicine, and the Department of Biology (Chilton), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Hilary J
authors.initials: HJ
authors.lastname: Burgess
authors.affiliation: Departments of Large Animal Clinical Sciences (Schvartz, Epp, Lohmann), University of Saskatchewan, Saskatoon, Saskatchewan, CanadaVeterinary Pathology (Burgess), University of Saskatchewan, Saskatoon, Saskatchewan, CanadaWestern College of Veterinary Medicine, and the Department of Biology (Chilton), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Neil B
authors.initials: NB
authors.lastname: Chilton
authors.affiliation: Departments of Large Animal Clinical Sciences (Schvartz, Epp, Lohmann), University of Saskatchewan, Saskatoon, Saskatchewan, CanadaVeterinary Pathology (Burgess), University of Saskatchewan, Saskatoon, Saskatchewan, CanadaWestern College of Veterinary Medicine, and the Department of Biology (Chilton), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Katharina L
authors.initials: KL
authors.lastname: Lohmann
mesh_terms: D041081:Anaplasma phagocytophilum / Q000276:immunology*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D025065:Borrelia burgdorferi / Q000276:immunology*; D002170:Canada; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D019084:Fluorescent Antibody Technique, Indirect / Q000662:veterinary; D006734:Horse Diseases / Q000097:blood / Q000175:diagnosis*; D006736:Horses; D008193:Lyme Disease / Q000175:diagnosis / Q000662:veterinary*; D015203:Reproducibility of Results; D012698:Serologic Tests / Q000662:veterinary
chemical_list: D000907:Antibodies, Bacterial
keywords: Anaplasma phagocytophilum; Borrelia burgdorferi; Canada; comparison; horses; serology