Spatial and temporal analyses of Dermacentor variabilis (Say) (Acari: Ixodidae) in central and eastern Canada

Dermacentor variabilis (Say) (Acari: Ixodidae) is a vector for pathogens that can impact human and animal health. The geographic range of this species is expanding, but there are some areas with limited up-to-date information on the distribution of D. variabilis. Therefore, the objective of this study was to describe the spatial and temporal patterns of adult D. variabilis activity in central and eastern Canada. Ticks were collected from companion animals by veterinary clinic staff. Suspected locations of tick acquisition were spatially projected, and a spatial scan statistic was used to identify statistically significant clusters of frequent submissions from veterinary clinics. Submissions were categorised by calendar week to evaluate temporal trends. In total, 1198 adult D. variabilis, one nymphal D. variabilis and one Dermacentor albipictus (Packard) were collected from the provinces of Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia and Prince Edward Island from April 2019 through March 2020. Peaks in adult D. variabilis submissions occurred in May and June. Most of the submissions were received from south-eastern Manitoba, eastern Ontario and central and western Nova Scotia. A statistically significant cluster of frequent submissions that included seven veterinary clinics was identified in Nova Scotia. These findings can be used to determine the locations and times at which humans and their companion animals should be considered at an increased risk of exposure to D. variabilis and the pathogens they carry.