U of G professor warns of threat posed by increasing tick populations
In recent years, researchers have seen a significant change in the prevalence of ticks across Southern and Eastern Ontario according to Andrew Peregrine, a clinical parasitologist at the Ontario Veterinary College (OVC). Peregrine, who moved to the OVC in 1997, remarked in an article by the Sarnia Journal, “I’m hearing from [veterinarians] all over Ontario about changes (…) even three-years-ago there were areas with no ticks, and now you go for a walk and the next day your dog has 20 engorged ticks.”
Blacklegged ticks, the primary vectors for Lyme disease, have largely been found in defined endemic areas of Southern Ontario including the north shores of Lake Erie, Lake Ontario, and the St. Lawrence River. However, over the past five years, blacklegged tick populations have not only increased but have expanded to regions of Eastern Ontario where they previously didn’t exist, according to Public Health Ontario (PHO). Last fall, health officials in Toronto began to warn the public after confirming that blacklegged ticks were found in the Rouge Valley. Furthermore, the ticks found tested positive for the bacteria which causes Lyme disease.
Peregrine attributes the increase in tick population to three factors: birds, bucks, and climate change. He notes in a May 2015 article by the Toronto Sun that 150 million to 175 million deer ticks latch on the backs of birds as they migrate from the northeastern sea board in the U.S.to Canada each year. Most land in Nova Scotia and Eastern Ontario. Meanwhile, the soaring population of white-tailed deer, the primary food source of the blacklegged tick, and warmer winters are also believed to conduce the growing tick population.
On the bright side, as summer is fast approaching, Peregrine notes that, “just because we have newly established ticks doesn’t mean we should stop going for hikes.” There are several safety precautions that can be taken instead. A tick infected with Lyme disease must attach to, and feed from, a human for 24 to 36 hours before the infectious bacteria is able to travel to the gut or salivary glands to infect the host. Therefore, PHO suggests that people should check themselves routinely after going outdoors and immediately remove any ticks before they are able to cause infection. Also, preventative measures such as wearing long pants and a long-sleeved shirt or using tick repellant containing DEET are advised.
Looking forward, the biggest concern for Peregrine is that we do not know how much the tick population is going to change over the next 20 to 30 years. “At the moment,” said Peregrine, “in Eastern Ontario, the distribution is moving about 45 kilometers northwest each year.”
While he acknowledges that, in reality, we can’t stop the ticks coming in, he believes one of the most important things is education.
“A lot of the issues are in education, making people aware of what’s happened, what the ticks look like and what (people) can do to reduce the risk of exposure (…) effectively, learning to live with ticks,” concluded Peregrine.
Photo by Andre Redke via CC BY-NC-SA 2.0
I live in Merrickville, Ontario, in the Rideau Valley corridor and there were no ticks to be seen here, in my experience, three years ago. Now I pull at least one a day off the cat and dog ( the dog is treated regularly with tick and flea repellent – there is no known tick repellent for cats that I know of ). I have been bitten three times this spring and summer but caught them within hours and treated the bites with tea tree oil ( a powerful anti-viral ). This happened DESPITE wearing longs pants and sleeves and spraying my clothes and myself with DEET when I go into the bush or fields. Let’s hope this population explosion is a cycle that will begin waning soon!