Tuberculosis (TB)

What is tuberculosis (TB)?

  • Tuberculosis (TB) is an infectious disease caused by TB bacteria.
  • TB bacteria usually attack the lungs but can also affect other parts of the body such as the kidneys, brain or spine.

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How is TB spread?

  • TB is spread through the air from one person to another.
    • The bacteria are released into the air when a person who has the bacteria growing in their lungs coughs, sneezes, or sings. Persons close by then breathe the bacteria into their lungs.
  • Usually TB is not spread easily. It takes close, long-lasting, or frequent contact with someone who is sick with TB disease to become infected with the TB bacteria.

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What is TB infection?

  • Most healthy people who are exposed to the TB bacteria do not get sick from TB.
  • The TB bacteria stay dormant and do not multiply. This is called TB infection.
  • People with TB infection:
    • do not look or feel sick
    • cannot spread the TB to other people
    • have a 10% risk of developing TB disease over the course of their lives

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What is TB disease?

  • TB disease can develop when the body’s defence system cannot stop the bacteria from growing. Once the bacteria starts to multiply they can damage the part of the body they have infected.
  • TB disease is most commonly found in the lung (pulmonary TB), however it can cause disease almost anywhere in the body such as the kidneys or spine.
  • TB disease that develops in areas of the body other than the lungs is called extra-pulmonary TB. Extra-pulmonary TB is not easily spread to other people.
  • A person with TB disease:
    • in his/her lungs or throat can spread TB to other people
    • in other parts of the body such as the kidneys or spine cannot easily spread TB to other people
    • usually feels sick

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What are the signs of TB disease?

  • Some of the symptoms of TB disease are:
    • cough lasting at least 3 weeks
    • coughing up mucous, phlegm (pronounced ‘flem’) or blood
    • chest pain when you cough or breathe
    • fever
    • sweating at night
    • loss of appetite
    • unexplained weight loss, tiredness or weakness
    • pain in your body where the TB bacteria are growing

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Who is most at risk for TB disease?

  • Persons who are most at risk for TB disease are:
    • people with HIV/AIDS
    • those with weakened immune systems due to disease
      and/or medications such as diabetes, cancer, kidney
      disease and immunosuppressive drugs
    • close contacts of a person with TB disease
    • people from a country with high rates of TB
    • children under the age of 5
    • those who work or live in nursing homes, clinics,
      hospitals, prisons, or homeless shelters
    • those who are malnourished, homeless, under housed,
      alcoholic dependant, or injection drug users

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How do I know if I have TB infection or TB disease?

  • Early diagnosis is very important in the control of tuberculosis.
  • tuberculin skin test (TST) can help determine if someone has been in contact with the TB bacteria. 
    • A nurse will inject a tiny amount of test fluid called tuberculin just under the skin of your forearm. This is not a vaccination.
    • You may have slight discomfort, such as itching and redness at the test site. You should not touch or cover the site.
    • A nurse will check your arm 48 - 72 hours after the TST was done to measure the result and determine if the test is positive or negative.
    • It cannot tell if you have active TB disease.
      • A chest x-ray will be necessary to determine if the TB bacteria have damaged your lungs. Your doctor may prescribe medication to prevent TB disease.

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Can TB disease be prevented?

  • There is a 10% risk that a person with TB infection will develop TB disease at some time in their life.
  • If you have TB infection your doctor may recommend medication to keep you from getting TB disease. This is called preventive treatment.
  • If your doctor prescribes preventive treatment it is important to take all your medication unless your doctor tells you to stop.

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Can TB disease be cured?

  • Yes TB can be cured with the right medicine.
  • You will need to take this medicine for 6 - 12 months in order to destroy all the TB bacteria and cure TB disease. Your doctor will decide exactly how many months you will need to take the medicine.
  • Once a person has been on this medicine for a few weeks, they usually cannot spread TB bacteria to other people.
  • It is very important that you take the medicine every day at the same time or as instructed by your doctor. Do not stop taking the medicine unless your doctor tells you to stop.
  • Failure to take your TB medicine as prescribed by your doctor can result in the development of drug resistant TB. The TB medicine can no longer cure the TB disease and your condition may actually worsen.

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Do I have to pay for the medicine?

  • No. Medicine to prevent or treat TB is provided free of charge through your local health department.
  • A public health nurse will stay in touch with you while you are taking this medicine.

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Is TB medicine safe?

  • Yes. When TB medicine is taken as it is prescribed it is generally safe.
  • Some people may experience some side effects.
  • Your doctor and public health nurse will tell about any side effects that you should report to them.
  • You will have blood tests to check for any side effects.
  • It is important that you tell your doctor if you do not feel well when you are taking your TB medicine.

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Is there a vaccine to prevent TB?

  • BCG (Bacille Calmette-Guerin) is a live vaccine given soon after birth to help protect infants and young children against the most severe forms of TB disease.
  •  It is generally given in countries where TB infection and TB disease are more common.
  • The following groups of people may have had the BCG vaccine:
    • persons born in countries with a high rate of TB
    • Aboriginal persons from communities with high rates of TB
    • persons born in Quebec and Newfoundland from 1940 to early 1980’s

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Can the BCG vaccine protect me from TB?

  • The protective effect of this vaccine decreases as a person ages and the closer they live to the equator. This vaccine is made from treated (attenuated) strains of TB bacteria and may cause a person to have a false positive tuberculin skin test (TST).
  • Persons who have the BCG vaccine:
    • may have a false positive TST
    • do not have permanent protection from TB
    • may still be at risk of infection
    • could have a serious allergic reaction to the BCG vaccine

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When reading a tuberculin skin test, when should a history of BCG vaccination be ignored?

  • A history of BCG vaccination should be ignored if a person:
    • had BCG in infancy
    • had contact with a case of active TB disease
    • is from a country with a high rates of TB
    • is from an Aboriginal Community with high rates of TB
    • has a weakened immune system
    • has a high risk medical condition such as diabetes or renal failure
    • has an abnormal chest x-ray

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Who can I call for more information?

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Fact Sheets

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