Volume 30, Number 10—October 2024
Research
Rapid Increase in Seroprevalence of Borrelia burgdorferi Antibodies among Dogs, Northwestern North Carolina, USA, 2017–20211
Table 2
Year | No. tests | Seroprevalence, no. (%) | Seroprevalence difference, % (95% CI)† | Incident seropositivity, no. (%) | Risk difference, % (95% CI)† |
---|---|---|---|---|---|
2017 | 2,130 | 2 (0.1) | Referent | 2 (0.1) | Referent |
2018 | 2,114 | 0 | NA | 0 | NA |
2019 | 2,447 | 12 (0.5) | 0.40 (0.09–0.71) | 12 (0.5) | 0.40 (0.09–0.70) |
2020 | 2,617 | 11 (0.4) | 0.32 (0.05–0.60) | 11 (0.4) | 0.33 (0.05–0.61) |
2021 | 3,033 | 12 (0.4) | 0.30 (0.04–0.55) | 10 (0.3) | 0.24 (−0.01 to 0.48) |
*Dogs were screened by using the IDEXX SNAP 4DX Plus assay (IDEXX Laboratories, Inc., https://www.idexx.com). Seroprevalence was defined as the proportion of results positive for Anaplasma spp. antibodies among all IDEXX SNAP 4DX Plus tests completed for each year of the study. Incident seropositivity was defined as the dog’s first Anaplasma spp.–positive result during the study period. A dog was considered Anaplasma spp. positive if it had a positive result for Anaplasma phagocytophilum or Anaplasma platys antibodies; the IDEXX SNAP 4DX Plus test does not differentiate between the 2 species. NA, not applicable. †Absolute measures of effect were analyzed by using generalized estimating equations with robust variance estimators to account for correlations that arise from repeated measures. Models assume an exchangeable correlation structure.
1Preliminary results from this study were presented at the Virginia Mosquito Control Association Annual Conference; February 14–15, 2023; Virginia Beach, Virginia, USA; and the North Carolina Mosquito and Vector Control Association Annual Meeting; November 15–17, 2023; Carolina Beach, North Carolina, USA.