HealthLink BC File #51, April 2012
- What is tuberculosis?
- How does TB spread?
- What is the difference between TB infection and TB disease?
- How long must I be exposed to TB before I can become infected?
- What are the chances of a TB infection becoming TB disease?
- What are the symptoms of TB disease?
- How can I be tested for TB?
- Where can I get tested?
- What do the results mean?
- What is the treatment?
- How can I reduce the risk of giving TB to other people?
Tuberculosis, also known as TB, is caused by germs that are spread through the air when a person with TB exhales. Anybody nearby is at risk of breathing these air-borne germs into their lungs. TB usually affects the lungs, but it can also affect other parts of the body, like glands, bones, joints, kidneys, the brain, and reproductive organs. A person with TB can die if they do not get treatment.
When TB germs are expelled into the air, they can stay in the air for several hours, depending on the environment. As the air containing the TB germs is breathed in by other people, the germs can attack the lungs and grow. This can cause damage to the lungs and the germs can then spread to other people. TB from parts of the body other than the lungs is not likely to spread to others. However, people with TB in other parts of the body may also have TB in the lungs, and therefore be able to spread the germs to other people.
TB infection occurs when you breathe TB germs into your lungs and your body's defenses stop the germs from growing. A person infected with TB will not feel sick, and cannot spread TB germs to others. This is also called Latent TB infection.
TB disease occurs when you breathe the germs into your lungs and the germs start to grow and become active. You may or may not feel sick, but when you have the disease you can spread TB germs to those around you. This is also called Active TB.
Usually a significant amount of exposure is needed to become infected with TB. However, this depends on many factors such as how infectious the case is, the age and the immune system of the exposed person, and the ventilation in the place where the exposure occurred. Therefore, if you think you have been exposed to TB, you should speak to your doctor or health care provider.
If you have Latent TB infection, you have a 5 to 10 per cent chance of developing Active TB disease over your lifetime. However, if your body's resistance to infection is lowered, there is a higher risk you can develop Active TB disease.
You can reduce your risk of Latent TB infection developing into Active TB disease by using preventive treatment for 9 months. Speak to your doctor or health care provider about preventative treatment.
Symptoms may include a cough lasting longer than 3 weeks, loss of appetite, weight loss, fatigue, fever or night sweats. If the disease is in your lungs you may also have chest pains and shortness of breath.
If TB has affected other parts of your body, the symptoms may vary.
A tuberculin skin test is used to test for Latent TB infection. It is not routinely used to test for Active TB disease. It is a two-part test. A tiny needle injects a small amount of a harmless test substance under the first layer of skin on your forearm. Although there is minimal risk, you will be asked to stay in the clinic for 15 minutes following the skin test to see if you experience any allergic reaction.
The reaction you may get from this is a raised area where the needle was given. If the area gets itchy, do not scratch it, instead apply ice.
Two or 3 days later, you must go back to have your reaction to the injection measured. Depending on your reaction, you may need further tests, such as a chest x-ray or a sputum (spit) sample.
Active TB is typically tested by examining the mucous produced from your cough. It is sent to a laboratory, and tested to see if there are TB germs present.
You can get tested at your local health unit, your doctor, or one of the following clinics:
655 West 12th Avenue
#100 - 237 Columbia Street East
New Westminster, B.C.
1952 Bay Street
When your skin test is measured, your test will be negative or positive.
If your skin test is negative, you probably do not have TB germs in your body. You may be asked to be re-checked in 2 months if you have had contact with someone with TB.
A positive skin test means you have been infected with TB germs or you had a vaccination against TB, known as a BCG vaccination. People who have had the BCG vaccination can still get infected with TB germs. You will need more tests to determine which of these reasons provided positive results.
A chest x-ray will be done to see if your lungs are affected. If your x-rays are abnormal, or you are feeling sick, you will be asked to give a sputum (spit) sample to test for TB germs.
If you develop Active TB disease, you must have treatment to cure you and to prevent you from spreading TB to other people.
Treatment consists of taking several types of pills regularly for at least 6 to 9 months. During this time, you will have several chest x-rays and sputum (spit) samples to check your progress.
Some people do not finish all the pills they are prescribed because they start to feel better. Even though you may start to feel better after only a few weeks or months of taking these pills, the germs are still active in your body. It is very important to take all the pills you are given, exactly as directed, until you have used up all of your medication.
If you do not take all the pills you are given for as long as the doctor or nurse tells you to, there is a good chance that the germs in your body will become resistant to the medicine.
If this happens, you may feel more ill than you were before, and you may need to have more treatment for a longer period of time.
You will still be contagious for at least 2 to 3 weeks after starting treatment. If you have TB of the respiratory system, you will be instructed to wear a mask and stay away from other people. This is to reduce the risk of spreading TB to others.
You will be asked where and with whom you have been in contact. All information you give will be kept confidential.
Any people you may have had contact with will be checked to see if they are infected too. If they are infected, they will be offered preventive treatment to make sure they do not develop TB disease.
To reduce the risk of giving TB to other people, take the following precautions until you are told you are not infectious:
- Stay at home and away from others;
- Wear a surgical mask to all medical and lab appointments;
- Cover your nose and mouth when coughing, sneezing or laughing;
- Use disposable tissue when coughing up and discard tissue in a waste basket or toilet;
- Avoid poorly ventilated spaces and rooms;
- Take all medicine as instructed; and
- Avoid being around young children.
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