5 things to know about tuberculosis in 2018 as Thunder Bay health unit confirms cases

Public health officials in Thunder Bay, Ont., have issued a warning about a reported small outbreak of tuberculosis in the city affecting four people.

The bacterial disease usually attacks the lungs but can also affect other parts of the body. The four cases confirmed by the health unit on Friday are being investigated, according to officials, but don't pose a significant risk to the general public.

• Thunder Bay health unit says tuberculosis confirmed in city

CBC Thunder Bay asked the Thunder Bay District Health Unit's associate medical officer of health, Dr. Emily Groot about the illness; here are five things to know about the disease:

Tuberculosis still active in Canada and in Thunder Bay

While the number of TB cases in Canada has largely decreased, hundreds of cases of the disease are still reported annually.

• Waterloo TB cases nearly double average yearly rate, Public Health reports

According to Health Canada, about 1,600 cases of active tuberculosis are reported to public health authorities each year. The Thunder Bay District Health Unit usually sees fewer than 10 per year, Groot said.

"Tuberculosis is much less common in Canada than it used to be," she said.

The number of cases of the disease steadily decreased between the 1940s and 1980s, according to Health Canada.

There is no standard vaccination for TB, Groot said, except in very specific circumstances.

The public is generally at a low risk

In confirming the four new cases of tuberculosis on Friday, public health officials said that the illness is not very contagious and it requires prolonged contact with someone who is sick to be at risk of becoming sick oneself.

"This is a really low risk to the general public," Groot said of the reported cases in Thunder Bay.

The disease is caused by the bacterium Mycobacterium tuberculosis, Groot said, adding that today, antibiotics are used to treat cases of tuberculosis.

"The prognosis for tuberculosis is usually pretty good," she said. "The medications that we have available unless the tuberculosis strain happens to be resistant are effective in treating tuberculosis."

Still, the illness, in certain circumstances, can be deadly. In Nunavut, where the prevalence of TB is much higher, Ileen Kooneeliusie, a 15-year-old girl, died in 2017. A Public Health Agency of Canada report showed that, in 2014, eight per cent of people with TB in Canada died during treatment.

• 'She was my only girl': Nunavut teen's death sheds light on failures in fighting TB

Environment, overall health play a role

The four cases of TB in Thunder Bay affected people "who lack adequate housing," according to a written release issued by the health unit on Friday. Groot added that one's environment can play a big role in contracting the disease.

"The fact that we see ... tuberculosis in Canada is really disappointing but [it] is a reflection of the challenges that some people face in terms of adequate housing and safe places to sleep at night," she said.

"I think the main thing we should be thinking about is, as a community, how can we ensure that people have access to safe housing and good nutrition that protects us from tuberculosis."

Groot added that the decline in TB cases in Canada in the mid-20th century largely corresponded with improvements to housing, ventilation systems and general health.

You can have the TB bacteria and not know it

Tuberculosis can be either active or latent, meaning someone infected can exhibit symptoms and be contagious or have the bacteria that causes the disease lay dormant.

"Globally, it's actually very common to have an infection that's not causing symptoms," Groot said, adding that almost one third of people around the world havethe bacteria "sequestered off in their body ... that usually doesn't make them sick."

Those numbers are much lower in Canada, she said. "Most Canadians aren't carrying the [bacteria] in their body."

In about five to 10 per cent of cases, those with the latent or dormant version of the disease see it turn active, according to a tuberculosis expert with Ontario Public Health.

This is more common in children, the elderly and those with compromised immune systems.

Know the symptoms, seek medical help if needed

Symptoms of active tuberculosis can include a newly-developing cough, coughing up blood, chest pain, swollen lymph nodes, weight loss, fever and night sweats, according to the Thunder Bay health unit.

On Friday,Groot said that public health officials are still investigating the four confirmed cases; she said additional cases may still be discovered.

"If anyone has concerns [or] they have symptoms, just to talk to their health care provider," she said.