You may have noticed that there are more lone star tick submissions displayed on the most recent set of maps. On the first set of maps, we only had 2 locally-acquired submissions, so they were lumped into the 'other' category. Over the past few weeks, we've had 6 more submissions, 5 of which were from Ontario, the other from Nova Scotia. They are labelled as yellow stars on the maps.
What does this mean? And should we be concerned?
The lone star tick, Amblyomma americanum, has been in the media a lot lately. It is known to be an aggressive feeder and a vector for several pathogens that can cause disease in humans and animals. Based on the current map produced by the Centers for Disease Control and Prevention, this tick is widely distributed across the central and eastern United States, including regions that border Ontario and New Brunswick. Many are concerned that the tick will expand its range into Canada, just as the blacklegged tick has done and continues to do.
Generally, we can think of a tick species as 'established' or 'adventitious' within a specific geographic area. Established means that multiple ticks have survived and are able to successfully reproduce over time. Adventitious means that the tick was 'accidentally' introduced, most commonly on a bird. It is very common for ticks to be brought up on migratory birds in the spring. However, the large majority of these ticks do not lead to established tick populations. Many factors must align for this to happen, including supportive ecological conditions like climate, habitat and hosts.
The lone star tick is the most common adventitious tick in Ontario. So we expect scattered submissions of this tick each year. This is exactly what we see on our current maps and does not raise any alarms. If we begin to see multiple submissions from the same area within a short period of time, we would want to follow-up with field sampling to gather more information on the tick populations in that area.
We know that some areas of Canada may be climatically suitable to the lone star tick, and that preferred habitat (forest with dense understory) and hosts (white-tailed deer) are also present. This is one reason why tick submissions from pets are so important - they can provide an early indication that tick populations are changing and allow us to better understand risk.
So keep doing those tick checks and remember to submit your findings.