I was scrolling through the list of ticks catalogued on this site the other day and noticed that a few are missing that deserve to be mentioned. Ixodes spinipalpis (no common name), for instance. The fact that this tick has no common name gives away something important about it: it's not very well known.
Despite not being commonly encountered, the geographic range of this western North American tick is known to include British Columbia and southwestern Alberta, extending down through the western states to southern California. Most specimens found in Canada have come from British Columbia, but the rarity of those encounters means that little can be said about the natural history or distribution of Ixodes spinipalpis beyond the fact that most specimens have been collected in the province's coastal areas or the Okanagan Valley. That doesn't mean they don't reside elsewhere in the province, only that they haven't (yet) been found there.
What we do know about Ixodes spinipalpis is that all stages like to feed on a wide range of rodents (pikas, shrews, wood rats) and members of the rabbit family (cottontails, hares) and they are much more likely to be encountered in the nests of their hosts than anywhere else. That being said, there is also evidence to suggest that this tick might be widespread in the woodlands surrounding those nests. It should also be noted that immature Ixodes spinipalpis ticks like to feed on birds.
Although specimens are occasionally collected from people, Ixodes spinipalpis doesn't appear to be particularly fond of biting us.
And that's a good thing.
Ick factor aside, Ixodes spinipalpis is known to transmit several illnesses to people, anaplasmosis, babesiosis, Lyme disease and Powassan's encephalitis among them. In fact, Ixodes spinipalpis reliably tests positive for Lyme bacteria in British Columbia and likely plays a key role in maintaining Lyme disease transmission cycles in nature.
Since no one really knows the full geographic range of Ixodes spinipalpis in British Columbia or Alberta, attempting to predict how that range could potentially expand (or contract) in response to climate change -- or any number of other factors -- over the coming decades would be premature. Maybe it will, maybe it won't. We've got to find them first, everything else will flow from that.
Photo by christie greene on Unsplash
