Multiple species of canine Rhipicephalus complex detected in Canada

Abstract

Multiple species of brown dog ticks have been described in the United States and the Caribbean: Rhipicephalus sanguineus sensu stricto (s.s.), also referred to as temperate lineage; R. linnaei (=tropical lineage); and R. rutilus (=southeastern Europe lineage) However, Rhipicephalus spp. are rarely recovered from dogs in Canada. To identify canine Rhipicephalus spp. in Canada and determine the influence of travel history on infestation, ticks morphologically identified as brown dog ticks (n = 93) collected from dogs (n = 13) in British Columbia, Ontario, and Québec, Canada were submitted with information regarding each dog's geographic location and travel history. Nucleic acid was extracted from available individual ticks (n = 86) and PCR was used to amplify sequences of a 12S rRNA mitochondrial gene fragment. Sequences were compared to published reference sequences of known species and a phylogenetic tree constructed. Twenty-three ticks (26.7%) consistent with R. linnaei were identified on seven dogs, including dogs from British Columbia and Ontario, with a median infestation intensity of 2 ticks/dog (mean = 3.3 ticks/dog). Sixty-one ticks (70.9%) consistent with R. sanguineus s.s. were found on two dogs from Québec and Ontario (median = 30.5 ticks/dog; mean = 30.5 ticks/dog). One dog from Ontario was infested with R. rutilus (n = 2) (2.3%). Species could not be determined for ticks from three dogs from Ontario and Québec. Most infested dogs (10/13; 76.9%) had a recent (< 1 month) international travel history. These data confirm that multiple species of canine Rhipicephalus are occasionally found in Canada and suggest introduction following travel is likely responsible for these infestations. Further analysis will allow for greater understanding of the range and diversity of canine Rhipicephalus spp. in North America and may reveal risk factors for infestation.

Keywords: 12S rRNA gene; Brown dog tick species complex; R. rutilus; R. sanguineus; Rhipicephalus linnaei; Travel.