American Dog Ticks (Dermacentor variabilis) as Biological Indicators of an Association between the Enteric Bacterium Moellerella wisconsensis and Striped Skunks (Mephitis mephitis) in Southwestern Manitoba, Canada.

ABSTRACT

Total genomic (g)DNA from 100 American dog ticks (Dermacentor variabilis) collected from humans, dogs, raccoons, and skunks near Minnedosa (Manitoba, Canada) in 2005 was tested for the presence of Moellerella wisconsensis (Gammaproteobacteria Enterobacteriales) using PCR. Although two gDNA samples derived from ticks attached to two striped skunks (Mephitis mephitis) contained M. wisconsensis DNA, it is unlikely that D. variabilis is a vector of this bacterium. Genomic DNA prepared from the washes of the external surfaces of these two ticks (i.e., before DNA extraction from the whole tick) and another two ticks attached to same skunks were also PCR positive for M. wisconsensis. This suggests that ticks acquired the bacterium by physical contact with contaminated or infected skunks. However, it does not exclude the possibility that the ticks may have also imbibed the bacterium from their host blood and lymph. Nonetheless, the results of this molecular study suggest that the four adult D. variabilis represent biological indicators of the presence of M. wisconsensis in association with their vertebrate hosts (i.e., striped skunks). Additional work is needed to determine if M. wisconsensis is present in the blood and lymph of striped skunks in southwestern Manitoba and if there are potential health risks for persons coming into contact with infected animals.