Tuberculosis (TB)
What is tuberculosis (TB)?
TB is a disease caused by a bacteria called mycobacterium tuberculosis . It is spread from person to person through the air.1 TB usually affects the lungs, but may also affect other parts of the body such as the brain, the kidneys, or the spine. TB is not highly contagious. TB can only be spread if someone with active TB disease of the lungs coughs or sneezes the germs into the air. A person in close, prolonged contact with someone sick with TB might breathe in these germs and become infected. However, not everyone infected with TB bacteria becomes sick. As a result, two TB-related conditions exist: latent TB infection and active TB disease.
- Diagram: How do you get TB? (PDF 53KB)
- Diagram: How does TB disease develop? (PDF 74KB)
Latent TB Infection and TB Disease
Persons with latent TB infection (LTBI) do not feel sick and don't have any symptoms, but usually have a positive TB skin test. They are infected with TB bacteria, but do not have active TB disease. People with latent TB infection are not contagious and cannot spread TB infection to others.
A skin test done at the doctor's office can detect TB infection. Individuals who have TB infection can continue to attend school. People infected with the TB germ can be given medication to prevent them from getting sick with TB disease in the future.
Everyone who is infected with TB germs is at risk of developing active TB disease at some point in their lives. The elderly, the immunocompromised, children under five years of age, individuals experiencing stress, or those with poor general health are at higher risk for developing active TB disease because their body's defences are weaker.
In people who have active TB disease, the germ is growing, causing damage and making them sick. The symptoms of active disease are fever, cough, weakness, unexplained pain that won't go away, night sweats, chills, weight loss and loss of appetite.2 Anyone with a cough lasting longer than three weeks should be checked by a doctor for TB.
For further information about Latent TB infection and TB disease, please view Peel Public Health's multilingual videos.
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TB Skin Test (TST)
TB skin test fluid contains purified protein derived from TB germs.3 A tiny amount of this test fluid is injected just under the skin of your forearm. This is not a vaccination or a blood test. The skin test cannot give you tuberculosis. It also does not protect you from getting TB. The skin test is able to detect TB antibodies. The test site must be read by a doctor or nurse within 48 to 72 hours to determine if the test is negative or positive. Documentation of the results should be recorded on your yellow immunization card.
A TB skin test will show whether someone has been exposed to TB germs. A positive skin test does not necessarily mean a person has active TB disease. A TB skin test is done for the following reasons: you are a contact of a person who has infectious TB disease; it is sometimes a requirement of employment or to determine past exposure as part of a medical assessment.
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TB Treatment
Tuberculosis is curable. Most people are treated at home under the supervision of their doctor. Usually after 2 to 3 weeks they are no longer contagious and can return to work or school after consultation with the physician. Medication must be taken every day for at least 6 to 9 months or as the doctor orders. The full treatment must be completed to prevent drug resistance from developing. 4
Drug resistance means that the drug is no longer effective in destroying the TB germ. Peel Public Health provides free TB medication and a program called Directly Observed Therapy (DOT) to help people with their TB treatment.
Preventative medicine, Isoniazid (INH), or Rifampin may be prescribed for persons with a positive skin test. Preventative medication has been shown to prevent TB infection from becoming TB disease. People that have a positive skin test and do not start or complete preventative therapy may develop tuberculosis disease in the future. 5
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