Tuberculosis

Tuberculosis is a contagious disease caused by a type of bacteria called Mycobacterium tuberculosis. The germ enters the lung, and grows slowly. It may not become active for many years. TB most commonly stays in the lung, but may also be carried through the blood to other areas such as the kidneys, bones or the brain. TB is easily treated with antibiotics if identified early. Individuals who have been infected with the TB germ, but who have not yet developed active TB, can also be prescribed medication to prevent them from becoming sick in the future.

TB is spread when someone who has TB coughs, sneezes, laughs, sings or even talks loudly and contaminates the air with tiny droplets that contain live germs. If such droplets are then breathed in by someone else, that person becomes "infected". Tuberculosis is most commonly spread when people are together in small, enclosed spaces that have poor ventilation. The TB germs must be breathed in from the air; you cannot get TB by touching things like door knobs or sharing food and utensils.

Being "infected" does not mean that you have active TB. People may remain well for many years while the TB germs remain in an inactive state. Active TB disease usually develops over a period of several months or even years, often when the immune system is weakened (for example, the elderly or those with HIV). When TB is not active, it cannot be spread to others. The only way to know if you have become infected is to be tested.

The symptoms of TB vary from person to person depending on the severity of the disease. In the early stages there may be no symptoms at all. As the disease advances, the most common symptoms include:

• a cough which does not go away;
• night sweats;
• fever;
• weight loss;
• chest pain; and
• fatigue.

Anyone who has persistent symptoms should have a check up by a nurse or physician. At that time, a skin test and/or a chest x-ray will be done and sputum (spit) samples will need to be sent for testing.

There are two kinds of TB tests used to identify if you have latent TB. The most common one is a TB skin test. Sometimes a blood test is also required to confirm that someone has latent TB.

A positive TB skin test usually indicates the presence of latent TB, which is a dormant form of TB that is not contagious. However, 5-10% of people may develop TB disease at a later time in their life, with children being at highest risk. You will get a chest x-ray and possibly be asked to collect sputum (spit) to check that you do not have active TB disease. If the presence of latent TB is confirmed, you will be advised to take medicine to prevent active TB disease from developing at a later time.

Active TB disease of the lungs is usually contagious, so people with TB disease are isolated in a special hospital room until sufficient treatment has been received. Another sputum test will be done to confirm that the person is no longer contagious.

As well, public health nurses conduct a contact investigation for all cases of active TB disease. The purpose of a contact investigation is to identify and treat anyone else with TB disease and to identify and offer preventative treatment for latent TB (latent refers to the condition that is not contagious). The number of contacts varies depending on how contagious the sick person was; how long they were sick before beginning treatment; and how many people they were in contact with. 

Advise your doctor or nurse if you are aware that you have been in contact with someone with active TB disease. Get a TB test and return for a second TB test if your health care provider says you need one. Take medicine to prevent TB if and as recommended. Exercise regularly, avoid smoking, and eat a healthy diet to avoid chronic diseases that can increase the likelihood of TB disease developing from latent TB.

A person with active TB disease usually feels unwell and has symptoms. Active TB disease in the lungs is contagious and is spread by coughing, singing, sneezing, and speaking.  People with active TB disease may have an abnormal chest x-ray and positive lab tests for TB.

People who have latent TB infection do not feel sick and have no symptoms. The TB germs in their body are in a “latent” state (dormant, inactive, or sleeping). People with latent TB infection will usually have a positive skin test (TST) and usually have a normal chest x-ray and negative lab tests. Latent TB infection is not contagious and does not spread to other people. About 5-10% of people with latent TB infection go on to develop TB disease.

• Tuberculosis(link is external) (Government of Canada)
• Tuberculosis: Get Tested, Get Treated and Get Cured!(link is external) (Health Canada)

• The TB skin test, also known as the Mantoux test, tells if your body has been exposed to the TB germ.
• The nurse will inject a small amount of fluid just under the skin of the left forearm.
• You will see a little bubble or blister appear right away at the injection site.  This is normal and it will soon disappear.
• After 2-3 days, you will be asked to see the nurse to have the area checked and the reaction measured.
• If there is no reaction after 2-3 days, you most probably have not been exposed to the TB germ.
• If there is a reaction, some redness and a small bump will appear on the arm.
• A measurement of 10 millimetres or more is "positive", and means you may have the TB germ in your body.  At that point, the nurse will request additional information and tests, including chest x-ray and the collection of sputum samples.  When results are abnormal, the nurse will then consult with a medical health officer who may then recommend a further course of action.