How to protect yourself from Lyme disease

While studying abroad in Australia in 2016, Ryann McIntire began experiencing severe joint pain, unstable blood sugar levels, brain fog and other debilitating symptoms. It got so bad that the then 21-year-old flew home to Massachusetts early in search of answers.

After a friend suggested that she might have Lyme disease, McIntire asked her doctor for a blood test, which confirmed she had the antibodies in her system. That result, as well as her symptoms in the years prior, led McIntire’s doctor to conclude that she had been living with Lyme disease for more than a decade—most likely since an elementary-school field trip in the early 2000s near her home in Cape Cod, after which a nurse pulled a tick from her scalp.

Black-legged ticks transmit the bacteria Borrelia burgdorferi, which causes Lyme disease. The condition was first identified in the 1970s in Lyme, Connecticut—hence the name—about 240 kilometres southwest of McIntire’s fateful field trip. Symptoms include fatigue, fever, joint pain, headache and chills, and they can appear anywhere from three to 30 days after a bite. That makes diagnosis a challenge, as does the fact that the symptoms are common to multiple illnesses, says Janet Sperling, an entomologist and president of CanLyme, the Canadian Lyme Disease Foundation. The one symptom unique to Lyme disease, a bull’s-eye-shaped rash, doesn’t occur in all patients.

Lyme disease is diagnosed by a blood test that detects antibodies made by the body in response to the infection, and it can treated with antibiotics. But if it goes undiagnosed, like in McIntire’s case, it can affect the central nervous system, resulting in a hard-to-treat, chronic condition called neurologic Lyme disease, characterised by brain fog, pain and muscle weakness.

The good news is that a vaccine to prevent Lyme disease infection is on the way. Moderna has two novel mRNA Lyme-disease vaccines in development. And Pfizer Inc and French drugmaker Valneva SE have a vaccine currently in Phase III trials. It’s expected to be available to the public in the next few years.

While a vaccine for dogs has been around since the 1990s, the first human Lyme vaccine, LYMErix, was taken off the market by its manufacturer in 2002, after only four years. At the time, sales were low, partly because the market was small and partly because of unproven claims that the vaccine caused arthritis.

Since then, cases have risen. Ticks thrive in warm, humid environments, and their habitat is expanding thanks to climate change. They live in wooded areas, on the edge of forests, under tree canopies and in tall grasses. The tick—and Lyme disease—has been found in nearly every province. The Public Health Agency of Canada reported roughly 3,000 cases of Lyme in 2021, but experts believe the true number could be as much as 10 times higher.

Until a vaccine is widely available, your best defence against Lyme disease is to avoid getting bitten by a black-legged tick, says Sperling. “We’re not going to get rid of them,” she says. “So we have to learn to live with them.”