Tuberculosis (TB) is one of the most common infections in the world. According to the World Health Organization, in 2018 about 10 million people were infected with TB and 1.5 million people died from the disease.. In Canada, there are about 1,800 new cases of TB every year. Fortunately, global TB cases are decreasing by about 2% per 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 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 is higher.
Babies, preschool children, and seniors are also at greater risk of reactivation due to weaker immune systems.