Preventative shot for Lyme disease promising — but precautions needed as tick populations grow, says expert

Over the course of two weeks last month, Isabel Deslauriers had to pluck four ticks off her husband.

Ticks weren't a common sight in their St. Eugene, Ont., backyard when they initially moved in 10 years ago. But now Delauriers worries about allowing her young nephew to play in the grass or letting her cat outside.

"It definitely makes you rethink what you do, where you walk," she said, adding that they now keep their lawn well manicured.

Ticks spread disease by latching onto a host and consuming its blood. If a tick is infected with Borrelia burgdorferi, the bacteria that causes Lyme disease, it can be transferred to the host.

Over recent decades, a warming climate, as well as changing land use, have contributed to growing tick populations in parts of Canada — including B.C., Manitoba, Ontario, Quebec, N.B. and N.S. — increasing cases of Lyme disease as well.

According to the latest data available from Health Canada, more than 2,600 preliminary cases of Lyme disease were reported in 2019. That's compared to 144 cases 10 years prior.

Currently, there is no vaccine available to prevent Lyme disease, though clinical trials are underway, meaning future vaccines are still years away. An approved vaccine against Lyme disease was discontinued by its manufacturer in 2002 due to limited consumer demand.

But a pre-exposure prophylaxis (PreP) injection currently in human drug trials could offer outdoor enthusiasts protection against ticks in the coming years.

'Treating the tick, not the human being'

The PreP injection works differently from a typical vaccine by using monoclonal antibodies, which have been used in treating cancer and other infections, to target the bacteria that causes Lyme disease.

"You get your injection and you just go out in the woods because the antibody is already in your body," said John Sullivan-Bólyai, deputy director of clinical and regulatory affairs at MassBiologics, the Boston company behind the injection.

When a tick begins to feed on a human host, those antibodies then enter the tick and kill the bacteria at its source, he said.

"We're actually treating the tick, not the human being," Sullivan-Bólyai told The Current's Matt Galloway.

MassBiologic's injection is undergoing an initial clinical trial in the United States, which is expected to end in April 2022. Sullivan-Bólyai said a key part of the study is to understand how long the antibodies survive in humans.

The goal is to provide protection against Lyme disease for the entirety of tick season, he added.

Sullivan-Bólyai is hopeful the injection could be available by 2023. "It's drug development. Hopefully we can do it faster and hopefully we're not going to do it slower," he said. 

Staying safe outside

Using PreP to prevent Lyme disease infections is promising, said Vett Lloyd, a biology professor at Mount Allison University in Sackville, N.B., noting it has an advantage over traditional vaccines: speed.

"You're not triggering the immune system as such and you don't have to wait for the immune system to catch up."

However, it is crucial to understand how long the antibodies last, and how it could affect individuals who have already been exposed to the bacteria that causes Lyme disease, she added.

In the meantime, Lloyd said Canadians should take certain precautions as they explore the outdoors this summer — even those living in urban areas.

"If you're out in a park with rough area, if you're out in the wilderness, if you're out camping, hiking — if you're golfing and you get the ball into the rough — all of that puts you into tick territory," she told Day 6 host Brent Bambury.

"Just like we have to be aware of the risk of sunburn or heat stroke or whatever else, there's a risk associated with everything, even crossing the road."

For those venturing outdoors, Lloyd offers some tips:

• Use an insect repellent that protects against ticks.
• If in a high-risk area, wear protective clothing that covers the skin.
• Check if you've been exposed when returning home. Lloyd says that newly-attached ticks can look like a poppy seed-sized freckle with legs.
• If a tick is found, remove it as quickly as possible. The longer it stays on the body, the higher chance of contracting a tick-borne disease. 

Written by Jason Vermes with files from CBC Radio's The Current. Interviews with Isabel Deslauriers and Vett Lloyd produced by Ashley Fraser.

Hear full episodes of Day 6 on CBC Listen, our free audio streaming service.