Tuberculosis (TB)

TB is spread through the air from one person to another when someone who is sick with active TB in the lungs coughs, sneezes, talks or sings. TB does not spread easily. It takes close, frequent and long-lasting contact with someone who is sick with the disease. TB is not spread by shaking hands, sharing dishes/utensils, clothing or touching surfaces that have been touched by someone with TB.

TB infection (TBI) is when someone has breathed in TB germs into their body, but their defense system has been able to stop the germs from growing. People with TBI:

• Do not feel sick and do not have symptoms
• Cannot spread TB to other people
• Have a normal chest-ray
• Have a 10% risk of developing TB disease in their lifetime

Active TB Disease is when someone who has breathed in the TB germs and their body’s defense system cannot stop the bacteria from growing. Once the active germs begin to grow, it can damage the body. Most times it is found in the lungs, but it can cause damage to other parts of the body including lymph nodes, bones, kidneys, stomach, and your brain. Active TB can be spread to other people.

• New or worsening cough lasting more than 3 weeks
• Coughing up blood
• Fever, chills or excessive sweating at night
• Loss of appetite or unexplained weight loss
• Tiredness or weakness
• Pain or swelling in other parts of your body where the TB germs are growing

People who are most at risk for developing TB disease are:

• Close contacts of a person with TB disease
• People who have lived or travelled to countries where TB is common
• People who had TB in the past and did not complete their prescription
• People with HIV/AIDS
• People with weakened immune systems from disease and/or medications (i.e. diabetes, cancer, kidney disease, and immunosuppressive drugs)
• Children under the age of five and the elderly
• People who are underweight
• People who drink heavily or smoke
• People who inject drugs

A tuberculin skin test (TST) can help determine if someone has been in contact with TB germs. A TB skin test must be checked 48-72 hours after it is injected. The TB skin test is NOT a vaccine.

A blood test called the Interferon Gamma Release Assay (IGRA) can also be done to see if a person has the TB germs. One type of IGRA blood test is called the QuantiFERON®-TB Gold Plus (QFT).

If you have a positive skin test or IGRA test, it cannot tell if you have active TB or TB infection. More tests will be needed including a health check-up, a chest x-ray and sputum collection.

TB medication can be used to treat and cure TB. TB germs are very strong and hard to get rid of, so it is important to take the medication every day until your doctor tells you that it is okay to stop. Your doctor will decide how many months you will need to take the medicine, it can be up to 6-12 months.

A person with a positive TB Skin Test or IGRA test can take TB medication to prevent them from getting Active TB Disease in the future. If you have TB infection, your doctor may recommend medication to keep you from getting sick. This is called “preventative treatment”. If your doctor prescribes preventative treatment, it is important to take your medication until the doctor tells you to stop.

No. All TB medications are available free of charge from Halton Region Public Health. A public health nurse will stay in touch with you while you are taking this medicine.

Yes. When TB medicine is taken as it is prescribed, it is safe. Some people may experience some side effects. It is important to tell your doctor right away if you do not feel well when you are taking your TB medicine.

Bacille Calmette-Guerin (BCG) is a vaccine for TB. It is a 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 Active TB disease are more common. The following groups of people may have had the BCG vaccine:

• People born in countries with a high rate of TB
• First Nations and Inuit people from communities with high rates of TB
• People born in Quebec and Newfoundland from 1940 to the early 1980s

BCG does not provide lifelong protection from TB infection or Active TB disease. It is most protective against certain types of TB in babies and young children. As a person gets older, the vaccine protection decreases so they may still be at risk for infection.

People vaccinated with BCG vaccine can sometimes have a false positive TB skin test. Sometimes, the QFT blood test is done to rule out a false positive. Since BCG does not provide a lifetime of protection, a person should ignore the BCG vaccine as a cause of a positive TB skin test if they:

• Had BCG in infancy
• Had contact with a case of active TB disease
• Is from a country with a high rate of TB
• Is from a First Nations or Inuit Community with high rates of TB
• Has a weakened immune system
• Has a high-risk medical condition (e.g. Diabetes, renal failure)
• Has an abnormal chest x-ray

A TST is not a vaccine, and it cannot give you TB. A tiny amount of test fluid is injected just under the skin of the forearm. There may be slight discomfort, such as itching and redness at the test site. The site should not be touched or covered after the injection. The reaction at the site is measured 48 to 72 hours after the TST was given. If the TST is positive, it means that you may have been in contact with TB germs. A TST cannot tell if you have active TB disease. If you have a positive TST, a chest x-ray will be required to determine if the TB germs are in your lungs.

A TST can help determine if you have been in contact with TB germs. You may need a TST for employment, student placement, volunteering purposes, before starting certain medication, travel or because you have been in contact with a person who has active TB.

Sometimes the immune system cannot remember a past TB infection and can cause people to have a negative reaction to the first TST. A second TST, given at least one week to as long as one year after the first TST, may produce a much greater response. A two-step TST is recommended for:

• Health care workers or people in homeless shelters
• Travelers planning a long trip to an area with a high rate of TB

Yes. Most people will have no side effects. The TST can cause pain, redness, rash, swelling, blistering, bleeding or a sore at the injection site, however these side effects are rare.

• People who currently have a major viral infection
• People who have received a live virus vaccine, (e.g., chickenpox, shingles, MMR, mpox, etc.) in the past 4 weeks

• People who have never had a TST
• People who had a previous TST and have no record of the results or the test results were not recorded in “millimeters” of induration (where the area becomes firm)
• Pregnant women
• People who have had a previous Bacillus Calmette–Guérin (BCG) vaccine
• People recently immunized with an inactivated (dead virus) vaccine (e.g., Polio, Hepatitis A)
• People who have had a COVID-19 vaccine. However, if the TST is negative and there is a high suspicion of TB, it is recommended for the individual to have a repeat TST 4 weeks after receiving the COVID-19 vaccine. This is to avoid missing persons with TB infection, as there is a possible risk that the COVID-19 vaccine could temporarily result in a false negative TST

• People who have had a previous severe reaction to a TST (e.g., blistering)
• People with severe burns or eczema on forearm where the test will be given
• People who are known to have had active TB or have a record of TB treatment
• People with a record of a positive TST recorded in “millimeters” of induration

IGRAs are blood tests that can help determine if someone has been in contact with the TB germs. The IGRA test cannot tell if you have active TB or TB infection. It can only tell if a person has the TB germs. The IGRA blood test measures the person’s immune response to the TB germs. There are currently two types of IGRA tests available in Canada: The QuantiFERON®-TB Gold Plus (QFT) and the T-Spot.TB Assay.

• When a person has had a positive TB skin test but they have not been around others that have active TB or in an area that has high rates of TB
• When a person has received a Bacillus Calmette–Guérin (BCG) vaccine after 1 year of age and/or has had BCG vaccination more than once
• To see if a person has TBI so that TB medications can be used to prevent a person from getting active TB
• For a person whose TST is not a good indicator of TB

• It only needs a single patient visit
• The results can be available in 2-10 days
• Getting the BCG vaccination as a baby does not cause a false positive result
• Results are not affected by other bacteria and viruses (germs)

• Cost is not covered by the Ontario Health Insurance Plan (OHIP)
• IGRA tests can only be done at certain laboratories. You will need to contact the laboratories to see where it is available
• IGRA tests are less effective on:
  • Children under 2 years of age;
  • Persons with weakened immune systems
  • Health care workers or other populations (corrections staff or prison inmates) that go for repeat testing

• To see if someone has have active TB
• When repeated testing is needed for healthcare workers or other populations (e.g. corrections staff or prison inmates) who are at risk for getting the disease

For people who have had a COVID-19 vaccine and had a negative IGRA and there is a high suspicion of TB, it is recommended for the individual to have a repeat IGRA test 4 weeks after receiving the COVID-19 vaccine. This is to avoid missing persons with TBI, as there is a possible risk that the COVID-19 vaccine could temporarily result in a false negative IGRA.