Trading posts brought tuberculosis to Quebec Arctic: study
McGill researchers say disease's persistence due mostly to social conditions such as overcrowded housing
Genetic research suggests the arrival of permanent trading posts in Arctic Quebec meant more than easier access to flour and metal cookware for Inuit families.
A newly published paper from McGill University concludes that's how tuberculosis was introduced into the region as well.
"It would appear that the tuberculosis epidemic dates to permanent interaction with some outside people," said lead author Marcel Behr.
Although TB is a distant memory in most of Canada, it still stalks the North. Last year, Nunavut recorded 83 cases, although that was an improvement. There were 100 cases in 2010, a rate of infection 63 times higher than that in the south.
In 2008, a study found Canada's four main Inuit regions had a tuberculosis incidence rate of 157.5 for every 100,000 people. The rate in southern Canada was 0.8 per 100,000.
In an attempt to understand why the respiratory disease remains so persistent in Arctic Quebec, Behr and his colleagues examined the genetic structure of tuberculosis bacilli found in 163 cases from the region known as Nunavik.
They found the great majority of them were very similar. Using known rates of genetic mutation for the TB bacillus, they were able to derive a pretty good idea of when the bug arrived among the Inuit — about 1919.
"The Inuit of northern Quebec had long-standing casual interactions with whalers and fishermen and explorers for probably about three centuries," Behr said. "We do not see any evidence that those three centuries led to (TB taking hold).
"After the early 1900s, you actually start to see formal installations and villages and trading posts. You have a much more permanent interaction."
The good news is that Behr's team couldn't find any evidence that Nunavik's TB strain is more virulent than others. Although some strains elsewhere on the globe are harder to treat or more antibiotic-resistant, Nunavik's is not among them.
"We could find absolutely no traces of a hyper-virulent bacteria. It is a relatively ordinary bacterium."
That suggests the disease's persistence is due almost entirely to social conditions such as overcrowded, substandard housing.
"It should be a controllable strain."
Behr said public health agencies have two ways to address the issue — treating the disease itself or treating the conditions under which it flourishes.
"You can either see TB as the problem, and then your goal is controlling TB, or you can see TB as a symptom of the problem, and then your goal should be broader.
"What we need is not brand-new interventions, but to scale up things that already exist and we have to apply them better."
Tuberculosis has left an indelible mark on Inuit culture. In the '50s and '60s, thousands of infected Inuit were sent south for treatment, many never to return.