The World Health Organization is ramping up its efforts to wipe out tuberculosis in countries with low rates of active TB by setting a goal of eradicating the disease by 2050 in 33 countries, including Canada.
Meeting that target will be a tall order for Canada, according to infectious disease experts in this country.
Although Canada has one of the lowest rates of active TB in the world, it faces some particular challenges in eliminating the disease – namely, the waves of immigrants and visitors it welcomes from countries where TB is endemic, and the slow but persistent increase in incidence rates among aboriginals, especially in Nunavut.
"One of the really big challenges in Canada is, from a TB standpoint, it almost looks like we are a low-incidence country fused with a high-incidence country," said Kamran Khan, an infectious disease physician and TB specialist at St. Michael's Hospital in Toronto.
Michael Gardam, the director of infection prevention and control at University Health Network in Toronto, said it was unlikely Canada would be able to meet the WHO goal.
"I think these [WHO] statements are important to focus people's attention on it, but tuberculosis continues to cause problems and is continuing to become more and more drug resistant," he said. "I think it's naive to think that we're going to be able to just eliminate this infection."
Federal Health Minister Rona Ambrose unveiled a new approach to combatting TB in March of this year, one that focuses heavily on aboriginals and new Canadians.
The public health arm of the United Nations announced on Thursday its own new framework aimed at TB elimination, which WHO defines as fewer than one new case per million people per year, by 2050.
The agency has set a "pre-elimination" goal of fewer than 10 new cases per million by 2035 in low-incidence countries.
Canada already meets the pre-elimination target among non-aboriginals born in Canada, according to the Public Health Agency of Canada.
But over all, Canada is still wide of the mark.
Canada logged 1,685 new cases of active tuberculosis in 2012, the last year for which nationwide statistics are available. That works out to a rate of 4.8 new cases for every 100,000 people, a slight uptick from the two previous years, when the figure was 4.7. It also reflects a steady decrease since 2002, when the figure was 5.3 per 100,000.
For aboriginal and foreign-born Canadians, the figures are less encouraging.
The incidence rates for aboriginals increased from 22 new cases per 100,000 population in 2002 to 29.2 per 100,000 in 2012.
The problem has been particularly acute in Nunavut, which had 76 new cases in 2012. For the tiny territory, that works out to an incidence rate of 234.4 per 100,000. The figure was down from 2010 when 100 cases were logged during an outbreak.
"In a nutshell, the reason we have high rates of TB is to do with socioeconomic factors," said Geraldine Osborne, the territory's acting chief medical officer of health. "The determinants are the living conditions of people here: Overcrowded housing, high rates of smoking, poor nutrition. We have all the risk factors."
In a bid to counteract those risk factors, the federal government contributed $800,000 to a research project in 2011-2012 that sent nurses and educators door-to-door in Iqaluit to test for latent TB, the dormant infection that produces no symptoms until a weakened immune system or other factors activate the disease.
Foreign-born Canadians accounted for two-thirds of all new active TB cases diagnosed in 2012. In Toronto, a magnet for new immigrants, between 90 and 95 per cent of new cases in the past three years have been found in people born elsewhere, with the top three countries of origin being Philippines, India, and China, according to Toronto Public Health.
But Canada's success in tamping down rates overall could wind up being its downfall, Dr. Gardam warned.
"On paper, Canada is doing pretty well," he said. "We have one of the lowest rates in the world … on the other hand, to be honest with you, we're kind of coasting. We don't have the same TB control programs that we used to have because as rates go down, people stop being interested in funding these sorts of things."