Early this year, I wrote a post talking about a newly identified tick species that may or may not be making its home in British Columbia. Since then, a collaborative study has been published by researchers in Ontario and Alberta that attempts to map out the current locations of Dermacentor similis ticks in Western Canada and the United States as well as identifying where they are likely to spread in the foreseeable future.
To do this, researchers used information tied to 29 Dermacentor similis ticks that were variously collected in British Columbia, California, Idaho, Oregon and Washington to create a distribution model to show where they are currently located. Then they input seven variables to determine other locations that are suitable for colonization currently and those that may be suitable in the future. The study determined that BC's Okanagan region is currently highly suitable for thriving populations of Dermacentor similis ticks.
I won't go through all the ins-and-outs of the parameters the were used to create the current distribution and future projection models, but if you feel you absolutely must know what they are, you can read them for yourself in the published paper.
What I will say is that not only is the Okanagan region particularly suitable for Dermacentor similis ticks now, modelling suggests that it will be in the future and that these ticks aren't likely to be expanding their territory much beyond its current boundaries. It must be noted, however, that very few ticks were used in this study and a larger study somewhere down the road that includes many more samples or different parameters may draw different or at least more robust conclusions. Time will tell.
So why do we care where Dermacentor similis ticks are located? Because closely related species, Rocky Mountain wood ticks (Dermacentor andersoni) and American dog ticks (Dermacentor variabilis) both transmit a mixed bag of pathogens that impact human health. Researchers currently don't know whether this newly identified tick species does as well, but if it does, it's important to know where they are located so that local citizens, doctors and veterinarians can be aware of their local level of risk.
I couldn't find a photo of Dermacentor similis ticks anywhere, but considering that they have long been mistaken for American dog ticks, I could probably safely have posted a picture of one of those and neither you nor I would have been likely to spot a difference (unless, of course, you happen to be an entomologist who specializes in ticks). Instead I've included a photo of Lake Okanagan taken from the vantage point of Peachland looking towards Kelowna in the distance.
Photo by Robbie Down @ Unsplash.
