Lyme disease spreading across Canada: review
Published Monday, June 8, 2009 5:39PM EDT
Lyme disease is moving its way into new parts of Canada but the government is not doing enough to track it or to teach doctors how to diagnose it, says a new report.
Lyme disease is transmitted by blacklegged ticks that feed on animal or human hosts and carry the bacterium called Borrelia burgdorferi. Practically unheard of in the 1980s, the disease is now found across the country, as ticks move into new parts of the country aided by climate change, write researchers in the Canadian Medical Association Journal.
"National surveillance must be able to identify this changing pattern," write Dr. Nicholas Ogden from the Public Health Agency of Canada and coauthors.
Populations of the tick that carry the bacteria that cause Lyme (Ixodes scapularis) are emerging in southern Ontario, Nova Scotia, southeastern Manitoba, New Brunswick and southern Quebec, they write. Populations of the tick that spreads the bacterium in the West, Ixodes pacificus, are also widespread in southern British Columbia.
"Current passive surveillance for tick vectors has identified new endemic areas, but additional methods are needed to precisely identify where Lyme disease is emerging in Canada," they write.
Public health officials need to better track the disease and inform both the public and doctors about the local risk level, prevention methods and the need for early diagnosis of Lyme disease, they say. They note that as of this year, doctors are required to report confirmed and suspected Lyme cases to the Public Health Agency of Canada.
But the problem remains that many patients with the disease are not being properly diagnosed. Robert Manten of Waterdown, Ont., is one of those who suffered for months without a diagnosis.
Manten was bitten by a deer tick on a camping trip in southern Ontario five years ago. He didn't notice the skin lesion that developed around the bite site and the bacteria were soon able to move into his blood and into his brain.
Within a couple of months, he became weak, plagued with headaches and eventually had to stop working. He went to 18 doctors, internists and neurologists and all of them missed the diagnosis, with some telling him his illness was all in his head.
Even though he had tests for everything -- including a test for Lyme disease -- all of it came back negative.
"It was a difficult time, not understanding why I was getting sick. My doctor thought it was a sinus infection but it continued to get worse," he says.
It took a year and a half and a specialized test to confirm he had Lyme disease. To treat the illness, Manten gives himself infusions of antibiotics twice a day. Four years later, he says he feels better, but is not free of the illness; he still has intense fatigue and has not returned to his job as an engineer.
Family doctor Dr. Ben Boucher, who has treated many patients with Lyme disease at his practice in Port Hawkesbury, N.S., says Manten's is a common story.
"There are a considerable number of patients being undiagnosed or misdiagnosed, and therefore not treated," he says.
"It's a concern because these patients get more ill as time goes on," says Boucher, noting that patients can develop facial palsy, cardiac issues and progress to nerve damage and inflammation of the brain and spinal cord.
"It is quite treatable and easily treatable [with antibiotics], but as it goes on into phase 2 and 3, it becomes more difficult to treat."
Part of the problem is that the standard blood test for Lyme disease is notoriously unreliable. It fails to detect the infection 20 per cent of the time.
Its accuracy is hampered by the fact that it can take up to six weeks after infection before the blood test can pick up elevated levels of Lyme bacteria antibodies. As well, the disease can go dormant for long periods, also making an accurate diagnosis difficult.
That's why scientists are urging doctors to be on the lookout for cases based on the sudden onset of disease symptoms, rather than on Lyme test results.
"Because the specificity of serologic tests for Lyme disease may not be high, epidemiologic findings about the likelihood of exposure to ticks that transmit Lyme disease inform the serologic diagnosis, rather than the other way around," the CMAJ authors write.
With a report from CTV medical specialist Avis Favaro and producer Elizabeth St. Philip