TB or not TB? 0
Most of us assume that tuberculosis (TB), the wasting lung disease that carried off millions during the Middle Ages and the Industrial Revolution, was conquered 50 years ago with the advent of antibiotics.
But with 350 new cases of active TB each year in Toronto, for example, we shouldn't be complacent.
"The disease has not disappeared, but people's perception of it within industrialized countries like Canada is that it disappeared because of antibiotics that can treat TB," says Toronto's Dr. Kamran Khan.
The burden of disease has shifted less from people who are born in Canada and more to those who were born outside of the country.
"In Toronto today, almost 95% of all cases of TB in the city are from people born in other parts of the world," explains Khan, an infectious diseases physician and scientist at St. Michael's Hospital. "That's because in many parts of the developing world, access to medicines to treat TB is not available."
TB is a serious and contagious disease with a long incubation but most people exposed to it (that's about one-third of us, globally) have healthy immune systems to keep the germ in check. But some people who may have acquired TB in their home countries may develop the disease even decades after coming to Canada.
If the disease is dormant, the chest screening that is done for immigration purposes may show nothing. Only if their X-ray is abnormal is a new Canadian given a skin test to see if they have TB in its active form. Even if they do not, those with abnormal X-rays are put under surveillance when they arrive -- seen by a doctor and followed by the local public health department.
A TB skin test can confirm whether or not you're a carrier or have the disease. But that test is not part of the immigration exam, says Khan. Of the 250,000 new immigrants to Canada each year, Khan estimates that 85,000 could be carriers. Their inactive infection could be easily treated, but if they develop active TB, they would require a lengthy and very costly multi-antibiotic treatment.
Once exposed to TB, people with weakened immune systems, including homeless people, are at a much greater risk of developing the active form of TB. While TB among the homeless used to be found mostly in those born in Canada, a study by Khan found that nearly 40% of all TB cases in Toronto's homeless population are in immigrants, and about 56% of all infections in immigrants involved TB strains not known to be already circulating in the city.
One reason for the spread of TB is that many of our shelters, often crowded, are constructed with what Khan calls "suboptimal ventilation," resulting in the homeless population being housed in crowded and confined spaces, becoming extra vulnerable to person-to-person infection. Even more disturbing is the threat that a new drug-resistant form of TB, already emerging elsewhere in the world, may soon come here.
"With that totally resistant form of TB, it would be like being in the pre-antibiotic era because it is resistant to every medication we have available," warns Khan.
"Like it or not, this is a problem we all own because we all travel and we will eventually see these cases here in our own backyard. TB is out of sight and out of mind, but it's here."
Did You Know?
What is TB?
TB is a serious contagious disease caused by a bacteria, Mycobacterium tuberculosis. While it usually infects the lungs, TB can also infect the kidneys, spine or brain. Learn more at lung.ca
How serious is it?
* Each year 1.4 million people die from TB in the world while nearly 9 million more contract it.
* The World Health Organization says extremely multi-drug resistant TB (XDR-TB) is "spreading at an alarming rate" throughout Europe. Eventually, we will see this form of TB in Canada.
* 650,000 patients around the world suffer from hard-to-treat multidrug-resistant TB.
* In Europe there are gaps in management of the disease, and TB kills seven people every hour.
Got a cough?
The main TB symptoms are a bad cough, fever, losing weight and feeling weak. Other symptoms include night sweats and coughing up blood. Ask your doctor for a test if you suspect have it. If you have an active form, you will likely need a long course of antibiotics.
Kamran Khan says that to control TB in Canada the country must implement more centres with specialized expertise and resources and a review and improvement of homeless shelter ventilation systems.