New test speeds up tuberculosis diagnosis in Nunavut, study finds

A new, faster test for tuberculosis could help patients get quicker treatment in Nunavut, where rates of the disease are among the highest in the country, according to a new study.

Qikiqtani General Hospital in Iqaluit was one of the first in Canada to use GeneXpert, a rapid TB test that can provide results in hours. Traditional tests can take weeks to diagnose the disease.

That allows doctors to put infected — and contagious — people on treatment far faster, which is better for their health and for the health of the people with whom they come in contact.

Ten years ago, it took about four weeks from the time Iqaluit resident Noah Papatsie coughed into a sample collection bottle until he found out he had active TB and started treatment.

"At the same time I was worried about, 'Am I giving it to this person? Am I giving it to that person?'"

Nunavut TB rate high

Nunavut's TB rate is about 50 times higher than of the Canadian average. The territory had 84 cases of TB in 2014 and has had 13 cases reported so far this year.

Despite that, the territory does not have a laboratory that can do TB testing; previously all samples were being sent to Ottawa. 

Traditionally, people who are suspected of having active tuberculosis are asked to produce a sample of sputum, mucus coughed up from the lungs. A smear microscopy test involves looking for TB bacteria under a microscope. The best test is a culture that involves trying to grow bacteria from the sputum sample but Mycobacterium tuberculosis, the bacteria that causes the disease, grows very slowly. 

The new test looks for the DNA of the bacteria in the sputum sample.

Detects 85 per cent of TB infections

A recent study published in CHEST Journal shows the rapid test is about 85 per cent successful at detecting TB in people who have it. The equipment needed to run the test is about the size of a computer hard drive​. Dr Gonzalo Alvarez, one of the authors of the study, calls it "a lab in a box."

"It is not one magic bullet, as they say, even though we would all hope for that but it adds to all the tools that we use to combat this terrible disease."​

A Toronto-based TB expert applauded the findings, but noted it would be better if the test were more sensitive. Dr. Michael Gardam says that with an 85 per cent sensitivity rate, doctors will still have to wait for smear tests — and maybe culture results — on 15 per cent of the suspected cases.

"So you're still stuck waiting for the culture," said Gardam, who is director of infection prevention and control for the University Health Network, a conglomeration of four University of Toronto teaching hospitals.

The study was funded by the Canadian Institutes of Health Research.