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Seroprevalence and evaluation of risk factors associated with seropositivity for Borrelia burgdorferi in Ontario horses
Author(s) -
Neely Megan,
Arroyo Luis G.,
Jardine Claire,
Moore Alison,
Hazlett Murray,
Clow Katie,
Archer Holly,
Weese J. Scott
Publication year - 2021
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/evj.13317
Subject(s) - seroprevalence , borrelia burgdorferi , lyme disease , veterinary medicine , tick , ixodes scapularis , medicine , odds ratio , epidemiology , serology , virology , immunology , antibody
Background Recently, the blacklegged tick ( Ixodes scapularis ), which is the vector of Borrelia burgdorferi , has undergone a range expansion from the northeastern and mid‐west United States to areas of southeastern Canada, including parts of Ontario. Understanding the seroprevalence of antibodies against B. burgdorferi in horses and risk factors for exposure is important for monitoring and preventing this emerging disease. Study design Cross‐sectional study of 551 horses in southern, central, and eastern Ontario, Canada. Objectives To assess the seroprevalence of B. burgdorferi in horses in Ontario, Canada; to evaluate risk factors associated with seropositivity; and, to compare the performance of two diagnostic tests. Methods Serum samples were obtained from clinically healthy horses in Ontario, Canada, along with completed questionnaires that were used for the risk factor analysis. Sera were tested with a Multiplex ELISA (Animal Health Diagnostic Center, Cornell University) and C6 ELISA (IDEXX SNAP ® 4Dx ® Plus test, IDEXX Laboratories). Results The seroprevalence of B. burgdorferi on at least one test was 17% (91/551), though only 15 (16%) horses tested positive with both tests. A spatial cluster of cases was detected in Eastern Ontario. The odds of being seropositive for B. burgdorferi on the C6 ELISA were significantly increased when oak trees were present by pastures (OR = 7.3 (1.8‐29.2), P = .005), while the odds were significantly decreased when regular tick checks were performed (OR = 0.1 (0.01‐0.7), P = 0.02). Main limitations Recruitment focused on known areas with blacklegged ticks as well as areas of higher horse density, which may have led to selection bias. Conclusions The expansion of blacklegged tick populations poses an ongoing risk for horses. Assessment of diagnostic testing options and risk factors is important for diagnosis and prevention, and with further investigation this information may be used to propose changes in management.