Tuberculosis: What you need to know

Tuberculosis (TB) is a contagious infectious disease that is spread through the air. Although it is mostly controlled in Canada, 1,600 new cases are reported in the country each year.

TB is considered one of the deadliest infectious diseases worldwide. One third of the world’s population is infected with the disease, which kills up to 1.7 million people each year.

How does it spread?

The disease is caused by a germ called the Mycobacterium tuberculosis. When a person with TB coughs, sneezes, spits, or even just talks or exhales, these germs become airborne.

The germs enter the body as a person breathes, and usually settle in the lungs before spreading throughout the body. TB is completely curable with antibiotics, but can result in death if left untreated.

A person generally has to have frequent contact with someone with TB in order to contract the disease.

Most people who are exposed to the germ do not actually get TB. The immune system is often able to kill the germ before it develops, or it can exist in the body in an inactive state called TB infection.

What are the symptoms?

Those with TB infection will not show any symptoms or spread the disease. Inactive TB can lay dormant in the body for years, and most people with the infection don’t even realize they have it.

About 10 per cent of those with a TB infection develop active TB. Once it becomes active, the individual will show symptoms such as fever, weight loss, chills, fatigue, and a cough lasting longer than two weeks.

Those most likely to develop active TB are people with weakened immune systems, such as children, the elderly, or those with HIV or AIDS.

When did TB first emerge?

It is uncertain when TB first emerged. Evidence of TB has been found in the tissue of ancient Egyptian mummies buried thousands of years ago, and the disease was documented by the ancient Greeks and Romans.

By the mid-17th century, TB or “˜consumption’ was ravaging Britain, where the disease caused one out of every five deaths.

In 1882, German biologist Robert Koch presented his discovery of the tubercle bacillus, the organism that causes TB. The discovery would earn him a Nobel Prize for medicine in 1905.

In Canada in the 1940s, there were 120 cases per 100,000 people. By 2005, the number had dropped to about 5.1 per 100,000.