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What is TB?

Tuberculosis (TB) is a serious disease caused by a germ, a bacteria called Mycobacterium tuberculosis. TB usually infects the lungs. TB can also infect other parts of the body, including the kidneys, spine and brain.

The main TB symptoms are a bad cough, fever, losing weight, and feeling weak.

TB is contagious. People who are sick with active TB disease spread TB germs through the air. It's important for people with TB to get treatment right away. TB treatments can cure TB and prevent it from spreading to others.

How do people catch TB?

Most people catch TB from someone at their home or work who has active TB disease. People with active TB disease spread TB germs in the air by:

  • coughing
  • laughing
  • sneezing
  • singing
  • playing a wind instrument (for example, the flute), or
  • talking

TB germs can stay in the air for hours. When people breathe air infected with TB germs, they bring TB germs into their lungs. Most people have strong immune systems that fight the TB germs and stop them from taking hold. But sometimes people's immune system can't fight the TB germs. The TB germs settle inside them, and they get inactive TB infection.

Are there other ways people can catch TB?

Yes. In rare cases, babies are born with TB that they got from their mothers, in the womb. This is called congenital tuberculosis. Babies with congenital tuberculosis usually show these symptoms when they are two or three weeks old: not eating much, not gaining weight, coughing, being very sleepy, being fussy (cranky). They may also have fever, fluid coming from the ears, and a rash.

Remember, TB germs spread through the air. TB germs do not spread by:

  • shaking hands
  • sharing food, drinks, or dishes
  • touching bed linens or toilet seats
  • sharing toothbrushes
  • kissing

What is inactive TB infection (also called latent TB infection)?

With inactive TB infection:

  • TB germs are alive in your body, but they're not growing
  • You do not have signs and symptoms of TB
  • You do not feel sick from TB
  • You are not contagious— you can't pass TB to other people

Treatment can cure an inactive TB infection.

If you don't get treatment for your inactive TB infection, it can get worse: you can get active TB disease. Inactive TB infection can turn into active TB disease at any time. Once you have active TB disease, you can have TB symptoms, you can feel sick, and you can pass TB to other people.

About 5 - 10% of people with inactive TB infection will get active TB disease later on. People with weak immune systems are more likely to get active TB disease.

Your immune system is what your body uses to protect you from sickness. Some things can make your immune system weaker: having another serious disease, having another infection (for example, HIV), being very young, being very old, not eating enough healthy foods (malnutrition), or taking certain medicines (for example, chemotherapy to treat cancer).

What should I do if I have an inactive TB infection?

If you have inactive TB infection, you must:

1. Get treatment to cure you of the TB infection.

2. Ask to be tested for HIV (human immunodeficiency virus, the virus that causes AIDS). It’s important to know if you have HIV. If you do, it will raise your risk of getting active TB disease.

How can I find out if I have inactive TB infection?

Ask your doctor for a test. Learn more about testing for TB.

What is active TB disease?

With active TB disease:

  • The TB germs are growing in your body and may be spreading
  • You may have TB symptoms like coughing, chest pain, and fever
  • You may feel sick, weak and tired
  • You are contagious — you can pass TB to people around you. On average people with untreated active TB disease infect 10 to 15 people a year1.
What should I do if I have active TB disease?

If you have active TB disease, you must get treatment right away. If you don't get treatment, you could get very sick or die. Treatment can cure you of TB and stop you from spreading it to others.

How do I know if I have active TB disease?

Ask your doctor for a TB test. Learn how doctors test for TB.

What is drug-resistant TB?

Drug-resistant TB comes from very strong TB germs. These germs are so strong that the usual TB medicines can't kill them. When TB can resist the usual TB medicines, it's called drug-resistant TB.

  • Sometimes TB resists the two most common TB medicines, isoniazid and rifampin. This is called multidrug-resistant TB or MDR-TB.
  • Sometimes TB resists many common TB medicines: isoniazid, rifampin, fluoroquinolone, and at least one of three injectable medicines (capreomycin, kanamycin, and amikacin). This is called extensively drug-resistant TB or XDR-TB.

Multidrug-resistant TB and extensively drug-resistant TB are very serious diseases. They can make you very sick and kill you. They are much harder to treat than regular TB.

People with drug-resistant TB:

  • need to take medicines for longer than other TB patients
  • may need to stay in the hospital for part of their treatment, in isolation (away from other people)
  • need to take stronger medicine than other TB patients. The stronger medicines:
    • don't work as well as the usual TB medicine
    • cause more side effects
    • are more expensive that the usual TB medicines. (Note that in Canada, most people get TB medicines for free).

If you have drug-resistant TB disease, you can spread it to others and make them very sick. That's why you must get special medical treatment right away.

How do people get drug-resistant TB?

You can get drug-resistant TB if:

  • you catch TB from a person who has drug-resistant TB disease
  • you already had TB disease but didn’t take all of your TB medicine. In this case, your regular TB can turn into drug-resistant TB.
  • you've already had active TB disease and been treated for it, and now you've got active TB disease again
  • your immune system is weak

Who is at higher risk of catching TB?

Anyone can get TB. You are at higher risk if you:

  • have lived, worked or travelled in countries where TB is common
  • have come into close contact with someone with TB (for example, family members or people sharing living spaces)
  • have HIV or AIDS
  • have a weak immune system (people who have had a serious disease or have had a transplant)
  • live in long-term residences (for example, seniors' homes)
  • live in crowded housing
  • live or have lived in a correctional facility (jail, prison)
  • are homeless
  • have already had active TB before
  • had TB in the past, but didn’t get proper treatment for it
  • live in communities with high rates of inactive TB infection or active TB disease
  • work with any of the above groups (for example, health-care workers and prison staff)

How common is TB?

Sadly, TB is a very common disease. More than 2 billion people — that's one third of the world’s population — are infected with TB. Ten percent of those people will become sick with active TB disease at some point in their lives. And every year, TB kills over 1.8 million people.1. Read more about TB around the world, and how the Lung Association is involved in fighting TB.

In Canada, TB is not very common. In 2008, we had 1600 cases of TB2. In Canada, TB is most common in two groups:

  • aboriginal people
  • immigrants and refugees who were born in countries where TB is common.

Learn more about TB rates in Canada from the Public Health Agency of Canada.

Learn more about TB

1. World Health Organization (2009). Tuberculosis facts: 2009 update (PDF), accessed from January 11, 2010.

2. Public Health Agency of Canada. (2010). Pre-release, Tuberculosis in Canada. Retrieved from March 9, 2010. Figures are provisional until publication of the Tuberculosis in Canada – 2008 Annual Report.

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