Why do Canadians record so few cases of Lyme disease as compared to Americans?

BY W. GIFFORD- JONES MD & DIANA GIFFORD-JONES

It’s tick season and the little pests are out with a vengeance. Tiny as they are, ticks are a huge nuisance and a hazardous vector of disease. Their ability to latch onto unsuspecting hosts has made them one of the most successful blood-sucking parasites on the planet.

Ticks are the primary carriers of Lyme disease, infecting people with their bite. Do ticks, or people account for the sizable difference in the number of reported cases in the US and Canada? Every year, in the United States, about half a million people are diagnosed with Lyme disease. Based on population, all other things equal, one would expect about 50,000 cases annually in Canada. Other things, however, must not be equal. According to the Public Health Agency of Canada, only 3,147 cases were reported in Canada in 2021, up from 144 in 2009.

Is geography behind this huge difference? Ticks that transmit Lyme are found in most parts of the US and have expanded into the areas of Canada where most people live over the past two decades.

Challenges with diagnosis of Lyme disease might help explain the gap. When diagnosed early, a course of antibiotics is an effective treatment. If untreated, the bacteria causing infection can linger in the body for months or years before presenting symptoms ranging, for example, from short-term fevers, rashes, and fatigue to more devastating conditions.

An attack on the central nervous system could be one manifestation. This can cause numbness, pain, stiff neck, headache, and many other symptoms, including psychiatric problems.

Another concern is the cardiovascular system, where Lyme disease can disrupt electrical signals that coordinate heart beats.

Painful swelling of joints is a common feature.

Celebrities have shared their experience with long lists of problems. Among them are musicians: Aril Lavigne, Shania Twain, and Darryl Hall, actors Alec Baldwin and Ben Stiller, writer Amy Tan, and even President George W. Bush.

How can these stars, and even a president, fall victim? Ticks are stealthy. They can bite people and feed for a day, or more before dropping off undetected.

Tick saliva is amazing stuff, containing: antimicrobials, analgesics, blood thinners, and immune suppressors in cocktails that change according to the situation. It’s this saliva that enables ticks to bite and feast without notice. What’s more, unlike female ticks, which become engorged, male ticks don’t eat such a big meal, making them very hard to notice.

Ticks can’t jump to catch a ride. They “quest” by perching on the tips of grasses, leaves, and branches, then use their forward legs to grab hold when a host brushes up. So stay out of long grasses in areas home to deer, rabbits and field mice. Be wary of other places where ticks might catch a human host. For instance, ticks are commonly found in grasses, bushes and treed areas of golf courses. Any pet dog stepping into long grass or jumping in and out of ditches could pick up ticks, and then bring them in the home where close contact with owners can easily occur.

Why do Canadians record so few cases of Lyme disease as compared to Americans? Lack of awareness of the disease among healthcare providers and low sensitivity of diagnostic tests are part of the answer. Additionally, one study found that Canadians tend to seek medical care less frequently for tick bites and are less likely to be tested for Lyme disease, leading to a 40% lower detection rate.