Tuesday, October 23, 2018, 2:09 PM – Fall has arrived. This is the season that transforms our forests with a beautiful display of colour and fills our kitchens with the smell of pumpkin pie and apple cider. It also brings something far less pleasant to our forests and hiking trails — blacklegged ticks.
In parts of central and eastern Canada, October and November are peak activity times for adult blacklegged ticks or “deer ticks”( Ixodes scapularis). Spring is also a peak time for adult activity, while nymphal blacklegged ticks are active late spring and early summer. This means they are hungry for blood and will climb up onto low lying vegetation in the forest to wait for their meal. This might be a deer or a raccoon — or it could be you, me or our pets.
Aside from the inherent revulsion many people feel towards ticks, some species pose a risk to human and animal health. The blacklegged tick can transmit several pathogens — most notably Borrelia burgdorferi, which can cause Lyme disease in humans, dogs and horses.
Lyme disease in humans is a potentially debilitating disease that can cause long-term symptoms like fatigue, joint pain, arthritis, facial paralysis and neurological disorders if left untreated. In dogs, the most characteristic sign is a shifting lameness, usually accompanied with general malaise. In rare cases, it can lead to a form of kidney failure.
As a veterinarian and researcher, my work focuses on ticks and tick-borne diseases, specifically those that affect both humans and animals. Over the past few years, we have certainly seen dramatic changes in our tick populations in Canada.
While this doesn’t mean we should curtail our outdoor activities, it does mean we need to think much more carefully about tick prevention.
Back in the early 1990s, the blacklegged tick population in Canada was restricted to Long Point, Ont. Over the past few decades, we’ve seen an ongoing expansion of its rangewith thriving populations now found in many areas of Ontario, Québec, Nova Scotia, New Brunswick and Manitoba.
Ticks — which themselves have very limited movement — are masters at hitching a ride on other animals, particularly migratory songbirds.
Each spring millions of ticks, blacklegged and other species, are introduced into Canada on migratory birds. Not all of these ticks will survive and reproduce but this does provide a seed for population expansion.
Spring bird migration is not a new phenomenon. But what is changing is our climate along with other ecological factors — such as host populations and habitat — that facilitate blacklegged tick survival and population growth.
Sufficient temperature is a basic requirement for many tick species. Temperatures need to be warm enough for long enough so the ticks can feed and undergo development. With climate change, more northern areas are becoming more suitable for blacklegged ticks.
Climate change also impacts forested habitatsand the distribution of wildlife species, all of which may further facilitate blacklegged tick range expansion.