26. Climate change, migratory birds, and four season tick awareness

We turn our gaze northward to Thunder Bay, Ontario to chat with entomologist Dr. Ken Deacon. While working on a contract with the Thunder Bay District Health Unit, he saw the first wood tick in the Thunder Bay area in 2003. He then saw the first black-legged tick in 2005 and has continued to follow the progression of their habitat expansion.

He points out that ticks can now be found in northern areas where they never existed in the past, and sees this as a clear indicator of climate change. Not only are the ticks living further north, they are also surviving through the winter. He has observed fluctuations in northern tick populations which appear to coincide with winter temperatures and snow cover. He notes that milder winter temperatures along with a deep insulating layer of snow give ticks a much better chance at surviving the winter. 

Thunder Bay is one of the stop-over areas for migratory birds and some of the other regions where Blacklegged ticks were first noted were other migratory nodes…it doesn’t take a deer to transmit, to move Blacklegged ticks or Deer ticks, free birds are the major culprits.”

Dr. Ken Deacon

Migratory ticks in flight

What is the role of birds in the spread of ticks to the north? Dr. Deacon points out that ticks hitchhike their way to many regions while attached to birds. Migratory birds bring ticks further north, and Thunder Bay is a stopover point on migration flyways. 

Dr. Deacon explains that increased tick populations often coincide with these migratory resting places. He notes that migratory birds have a much larger range than animals such as deer, and in fact can transport ticks to virtually anywhere in Canada. He urges physicians to keep this in mind when patients come in with symptoms of Lyme disease in any area of the country. 

Although tick populations fluctuate from year to year, Dr. Deacon notes that the National Microbiology Lab has stopped testing ticks submitted by the general public. He explains the difference between passive and active surveillance, and postulates that during the pandemic, the general public has been less comfortable visiting health units to submit ticks they’ve found, and consequently less ticks have been submitted since the beginning of COVID-19. He believes that these two factors may have played a role in lower tick counts in 2020.   

“Ticks can’t fly but they certainly can hitch a ride on someone (birds) that can fly great distances. So you could basically get Lyme disease anywhere in Canada, and physicians have to be aware of the fact that if someone comes in with Lyme disease symptoms, they probably have Lyme disease.”

Dr. Ken Deacon

We remind our listeners that you can always submit ticks for testing to Geneticks, Canada’s first private lab dedicated to providing accessible and reliable service for testing ticks for tick-borne diseases. To learn more, listen to our podcast with Geneticks founder, Justin Wood.

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The role of white-footed deer mice as a “Borrelia reservoir”

Sarah notes that when ticks are born they don’t carry Borrelia (Lyme bacteria). Dr. Deacon explains the role of the deer mouse as a “reservoir” for Borrelia. When a tick feeds on a deer mouse that carries Borrelia, that mouse will become a carrier of the bacteria. Ticks feed once during each stage of their life cycle, so if one of these meals contains Borrelia, the tick is able to transfer that to a human host. He notes that mice that carry the bacteria survive through winter and enable the bacteria to survive as well. 

Understanding the nature and life cycle of ticks plays an important role in prevention of Lyme disease. Although wood ticks and adult blacklegged ticks are more likely to be found at certain times during the year, nymphal ticks are still present and active during July and August and are on the lookout for their next meal. Nymphal ticks are much smaller than adult ticks, and Dr. Deacon suspects that they are responsible for around 70-80% of transmission in humans.

A close encounter with Lyme disease

Dr. Deacon explains how his passion for public information and participation grew after his spouse contracted Lyme disease about 10 years ago. He recalls that it was their optometrist who first pointed to Lyme disease as a cause of his spouse’s symptoms. He grew even more passionate about better education regarding Lyme disease after the experience his wife had in the emergency department. 

Seeking answers for the sudden onset of ice-pick headaches, his wife was considered as a possible drug addict or person with mental health issues. She experienced other neurological symptoms such as Bell’s Palsy, and her family physician ordered a blood test for Lyme disease which came back positive, allowing for treatment to begin. He is aware that a delay in diagnosis can lead to long standing neurological damage and the need for lengthy treatment. 

“They treated her in emergency first of all as if maybe she was a drug addict, and then the second time she went back to emergency, they treated her as if she had a mental illness.”

Dr. Ken Deacon

Four season tick awareness 

Sarah congratulates the Thunder Bay District Health Unit and Dr. Deacon for their role in raising awareness about ticks and Lyme disease. He notes that ticks have been found further north than Thunder Bay and that although they may initially be transported by migratory birds, ticks will become established further north when they are able to survive the winter due to climate change. 

Dr. Deacon looks forward to a day when the general public is aware that ticks are present and active throughout the year, and people take personal responsibility by being aware and doing tick checks. He leaves us with a “chilling” fact about ticks – that they can be active in temperatures as low as 4 degrees celsius, and calls on all of us to be eternally diligent. Thank you Dr. Deacon for the work you are doing to help educate the public and raise awareness about ticks and Lyme disease! And one more shout out to the Thunder Bay District Health Unit for the important role they are playing…gathering scientific data and informing the public!

“A lot of people think that during the period of snow you’re safe. You’re still not even safe in the wintertime if it’s a mild day, so…eternal diligence!”

Dr. Ken Deacon

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Thunder Bay District Health Unit