In this factsheet:
The Facts on Tuberculosis
Causes of Tuberculosis
Symptoms and Complications of Tuberculosis
Diagnosing Tuberculosis
Treating and Preventing Tuberculosis

The Facts on Tuberculosis

Tuberculosis (TB) is one of the most common infections in the world. About 2 billion people are infected with TB and nearly 3 million people are killed by it each year. In Canada, there are about 1,600 new cases of TB every year.

The bacterium that causes TB is called Mycobacterium tuberculosis. Someone can become infected and yet not have any symptoms of the active disease - this is called inactive TB.

For someone with a healthy immune system, there's only a 10% lifetime chance of the TB bacteria reactivating and causing the active symptoms of TB. If the immune system has been weakened because of HIV (human immunodeficiency virus) or other illnesses, the risk of moving from an inactive infection to an active symptomatic disease increases to 10% per year.

Babies, preschool children, and seniors are also at greater risk due to weaker immune systems
Causes of Tuberculosis

Only people who have active TB infections can spread the TB bacteria. Coughing, sneezing, even talking can release the bacteria into the surrounding air, and people breathing this air can then become infected. This is more likely to happen if you're living in close quarters with someone who has TB or if a room isn't well ventilated.

Once a person is infected, the bacteria will settle in the air sacs and passages of the lungs and, in most cases, will be contained by the immune system.

Your chances of becoming infected are higher if you come from - or travel to - certain countries where TB is common. People who are at greater risk for TB infection include the elderly, homeless people, people with substance use problems, individuals who have spent time in a correctional facility,