Exposure to Tick-Borne Pathogens in Cats and Dogs Infested With Ixodes scapularis in Quebec: An 8-Year Surveillance Study

Abstract

Cats that spend time outdoors and dogs are particularly at risk of exposure to ticks and the pathogens they transmit. A retrospective study on data collected through passive tick surveillance was conducted to estimate the risk of exposure to tick-borne pathogens in cats and dogs bitten by blacklegged ticks (Ixodes scapularis) in the province of Quebec, Canada, from 2010 to 2017. Blacklegged ticks collected from these host animals were tested by PCR for Borrelia burgdorferi sensu stricto, Borrelia miyamotoi, Anaplasma phagocytophilum, and Babesia microti. A total of 13,733 blacklegged ticks were collected from 12,547 animals. Most ticks were adult females and partially engorged. In total, 1,774 cats were infested with ticks and 22.6 and 2.7% of these animals were bitten by at least one tick infected with B. burgdorferi and A. phagocytophilum, respectively. For the 10,773 tick infested dogs, 18.4% were exposed to B. burgdorferi positive ticks while 1.9% of infested dogs were exposed to ticks infected with A. phagocytophilum. The risk of exposure of both cats and dogs to B. miyamotoi and B. microti was lower since only 1.2 and 0.1% of ticks removed were infected with these pathogens, respectively. Traveling outside of the province of Quebec prior to tick collection was significantly associated with exposure to at least one positive tick for B. burgdorferi, A. phagocytophilum and B. microti. Animals exposed to B. burgdorferi or B. miyamotoi positive tick(s) were at higher risk of being concurrently exposed to A. phagocytophilum; higher risk of exposure to B. microti was also observed in animals concurrently exposed to B. burgdorferi. The odds of dogs having B. burgdorferi antibodies were higher when multiple ticks were collected on an animal. The testing and treatment strategies used on dogs bitten by infected ticks were diverse, and misconceptions among veterinarians regarding the treatment of asymptomatic but B. burgdorferi-seropositive dogs were noted. In conclusion, our study demonstrates that cats and dogs throughout Quebec are exposed to blacklegged ticks infected with B. burgdorferi and A. phagocytophilum, and veterinarians across the province need to be aware of this potential threat to the health of pets and their owners.

Keywords: Anaplasma phagocytophilum; Babesia microti; Borrelia burgdorferi; Ixodes scapularis; cat; dog; vector-borne; zoonosis.

Figure 1

Administrative regions, regional county municipalities, population ecumene (i.e., land with population density ≥0.4 persons per km²) and sparsely populated areas (i.e., unpopulated land or land with population density <0.4 persons per km²) of the province of Quebec, Canada. Administrative regions are: 01: Bas-Saint-Laurent, 02: Saguenay-Lac-Saint-Jean, 03: Capitale-Nationale, 04: Mauricie, 05: Estrie, 06: Montréal, 07: Outaouais, 08: Abitibi-Témiscamingue, 09: Côte-Nord, 10: Nord-du-Québec, 11: Gaspésie-Îles-de-la-Madeleine, 12: Chaudière-Appalaches, 13: Laval, 14: Lanaudière, 15: Laurentides, 16: Montérégie, 17: Centre-du-Québec.

Figure 2

Daily number of dogs (n = 10,773) and cats (n = 1,774) infested with at least one adult tick in Quebec, Canada using a 7-day moving average on data from 2010 to 2017.

Figure 3

Number of cats infested with blacklegged ticks from 2010 to 2017 by regional county municipality considering the population ecumene (i.e., land with population density ≥0.4 persons per km²) and sparsely populated areas (i.e., unpopulated land or land with population density <0.4 persons per km²) of the province of Quebec, Canada. In total, 1,696 cats that did not travel out of their municipality of residence within 14 days of tick collection were included.

Figure 4

Percentage of cats exposed to Borrelia burgdorferi infected tick(s) among 1,696 cats infested with blacklegged ticks. Data covers from 2010 to 2017 by regional county municipality considering the population ecumene (i.e., land with population density ≥0.4 persons per km²) and sparsely populated areas (i.e., unpopulated land or land with population density <0.4 persons per km²) of the province of Quebec, Canada. Only cats that did not travel out of their municipality of residence within 14 days of tick collection were included.

Figure 5

Percentage of cats exposed to Anaplasma phagocytophilum infected tick(s) among 1,696 cats infested with blacklegged ticks. Data covers from 2010 to 2017 by regional county municipality considering the population ecumene (i.e., land with population density ≥0.4 persons per km²) and sparsely populated areas (i.e., unpopulated land or land with population density <0.4 persons per km²) of the province of Quebec, Canada. Only cats that did not travel out of their municipality of residence within 14 days of tick collection were included.

Figure 6

Number of dogs infested with blacklegged ticks from 2010 to 2017 by regional county municipality considering the population ecumene (i.e., land with population density ≥0.4 persons per km²) and sparsely populated areas (i.e., unpopulated land or land with population density <0.4 persons per km²) of the province of Quebec, Canada. In total, 7,644 dogs that did not travel out of their municipality of residence within 14 days of tick collection were included.

Figure 7

Percentage of dogs exposed to Borrelia burgdorferi infected tick(s) among 7,644 dogs infested with blacklegged ticks. Data cover from 2010 to 2017 by regional county municipality considering the population ecumene (i.e., land with population density ≥0.4 persons per km²) and sparsely populated areas (i.e., unpopulated land or land with population density <0.4 persons per km²) of the province of Quebec, Canada. Only dogs that did not travel out of their municipality of residence within 14 days of tick collection were included.

Figure 8

Percentage of dogs exposed to Anaplasma phagocytophilum infected tick(s) among 7,644 dogs infested with blacklegged ticks. Data cover from 2010 to 2017 by regional county municipality considering the population ecumene (i.e., land with population density ≥0.4 persons per km²) and sparsely populated areas (i.e., unpopulated land or land with population density <0.4 persons per km²) of the province of Quebec, Canada. Only dogs that did not travel out of their municipality of residence within 14 days of tick collection were included.