New research is helping us understand Lyme disease better

Published: February 27, 2019

Ixodid tick (Dermacentor sp.) (male) Photo by photowind/Shutterstock

Lyme disease is probably a much bigger problem than we’ve suspected in Canada, but efforts to combat it may start improving, now that we have a handle on just how often it’s not diagnosed.

Canadian researchers published findings last October that suggested that Lyme disease cases are vastly under-reported in Canada. Vett Lloyd, a biology professor at Mount Allison University in New Brunswick, and Ralph Hawkins, a clinical associate professor at the University of Calgary’s Cumming School of Medicine, used several investigative approaches to get a grip on how many Lyme cases there might actually be in Canada, as opposed to how many are actually identified and treated.

Lyme disease is a debilitating illness caused by a bacterium, Borrelia burgdorferi, that is transmitted through bites by black-legged ticks. Between three days and one month after a bite by an infected tick, a patient may show such early symptoms as fever, headache, muscle and joint pain, fatigue, and an expanding red rash. If left untreated by antibiotics, symptoms can progress to heart palpitations, arthritic symptoms, extreme fatigue and general weakness, and central and peripheral nervous system disorders.

“Any surveillance system of a disease under-detects,” says Lloyd, a founding member of Mount Allison’s Lyme Research Network, who has had Lyme herself. “No one knew to what extent that was happening with Lyme disease in Canada.” A recent study by the Centers for Disease Control and Prevention had already flagged an under-reporting problem in the United States.

For Canada, Lloyd and Hawkins came at the puzzle in three ways. They compared reported Lyme disease rates along both sides of the Canada-U.S. border, between Maine and New Brunswick. They looked at reported disease rates for dogs and humans in New Brunswick, taking into account that where tick bite frequencies are concerned, “dogs are furrier and spend more time rolling in grass than humans.” Finally, they looked at the “drop out rate” of Lyme disease blood test results. For the disease to be formally diagnosed in humans, the bacteria has to be detected in two successive tests. Out of every 10 Canadians tested, only one was positive on the second test.

Lloyd and Hawkins produced a staggering conclusion: an estimated thirty-fold difference in actual versus reported (and treated) cases of Lyme disease, at least in New Brunswick. Lloyd suspects that Ontario might be faring slightly better. The number of reported cases in Canada grew from 144 in 2009 to 2,025 in 2017, but if the estimate for New Brunswick’s under-reportage were applied nationwide, there could be about 60,000 or more undiagnosed cases a year.

Lloyd attributes the under-reportage to several factors. One is that people aren’t being diagnosed for the disease because Lyme doesn’t occur to them or their physicians as a diagnosis, which means that we need to better educate the public and the health care system. Another is that people are treated when their Lyme disease is acute and physicians are not considering that the disease is at play. Finally, blood tests are failing to identify the bacteria because the test doesn’t work well for nine out of 10 people. The reason may be that the bacteria in Canada has enough genetic variability that the test sees the bacteria on the first test, but not on the second.

But what does a “thirty-fold” difference in actual versus diagnosed cases mean? “If 30 people have Lyme disease, 10 might get the blood tests, and of those, only one will be positive on the first and second tests,” says Lloyd. “If you’re not positive on the second test, you don’t get treated. Twenty-nine out of 30 cases not being treated is a big problem.”

Lloyd emphasizes that someone being counted as a Lyme disease case (which requires the verifying two-step blood test) “is only important for people making decisions about health care spending. Not counting people leads to the disease being considered rare and unimportant. However, what really matters is treatment.” People who find a tick on them or have a bull’s eye rash and get to a doctor who recognizes Lyme disease and has them treated, she notes, are in a much better situation than someone who gets the blood test and fails to have the disease detected. The former may or may not be “counted” as a Lyme disease case (because there was no blood test), “but what matters is that they get treated.”

The good news is that Lyme disease is getting much more attention than it once did. In 2014, the federal government passed an act that required Ottawa to develop a federal framework on the disease, based on three pillars: medical surveillance; education and awareness; and guidelines and best practices. A  conference to develop the federal framework was held in May 2016. That conference identified a host of issues contributing to Canada’s problematic performance on identifying and treating Lyme. Among them was a general lack of awareness in the medical community of the disease and the ticks that transmit it, leading to misdiagnosis, and inadequate diagnostic tests that lead to both false positive and false negative results.

In May 2017, the Federal Framework for Lyme Disease was published, outlining government commitments over a five-year period to deliver on the three pillars defined in the 2014 act. Last October, the federal health minister announced $4 million for a Pan-Canadian Research Network on Lyme Disease, “to generate knowledge and improve diagnosis and treatment.” The federal government also announced $1.25 million from the Infectious Diseases and Climate Change Fund for five new projects “to increase Canada’s capacity to respond to the health impacts of Lyme disease.”

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