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Tuberculosis (TB)

Tuberculosis (TB) is an infectious disease caused by TB bacteria and is spread through the air from person to person. Learn about TB disease symptoms, risks, treatment and who to call for more information.

Tuberculosis (TB) is an infectious disease caused by TB bacteria that usually attack the lungs. Other parts of the body, including kidneys, brain and spine can be affected as well. TB spreads through the air, from one person to another.

The Public Health Department makes sure to investigate all cases of tuberculosis (TB) and works with health care professionals in managing tuberculosis cases. In addition, we ensure clients have access to free medication. Below are the steps taken to manage and contain outbreaks as well as educate citizens about TB.

Case Management
(Latent and Active TB)

  • Ensure adequate TB treatment is received and completed
  • Follow-up of individuals exposed to TB
  • Educate clients and contacts
  • Order TB medication for clients with TB

Direct Observed Therapy

  • Ensure clients take medication correctly
  • Monitor for side effects
  • Prevent/reduce drug resistance caused by interrupted drug therapy

Immigration Medical Surveillance

  • Immigration Medical surveillance is a requirement of IRCC.
  • Immigrants, refugees, visitors, visa students/workers identified through immigration surveillance are monitored for TB disease
  • Order TB medication for clients with TB infection on immigration and routine surveillance


  • Provide free educational materials, community agencies and health professionals
  • Outreach to populations at higher risk for TB disease

TB and Tuberculin Skin Test (TST) Frequently Asked Questions

Tuberculosis spreads through the air when a person with TB coughs, sneezes, or sings and then other people breathe that bacteria into their lungs. Usually TB does not spread easily. It takes close and frequent contact with a person sick with TB to become infected with the bacteria.

Tuberculosis Infection

  • TB bacteria stay dormant and do not multiply.
  • Most people exposed do not get sick from TB.
  • People with TB infection:
    • do not look or feel sick
    • cannot spread TB to others
    • have a 10% risk of developing TB disease

Tuberculosis Disease

  • TB bacteria multiply when the body's defense system cannot fight the growth.
  • Most commonly found in the lungs. Extra-Pulmonary TB develops in other parts of the body and is not easily spread to others.
  • People with TB disease:
    • can spread TB to other people if the disease is in their lungs or throat
    • usually feel sick

Tuberculosis Symptoms

  • Cough lasting at least 3 weeks
  • Coughing up mucous, phlegm, 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

Individuals with any of the following conditions are most at risk for TB disease:

  • Weakened immune systems due to disease and/or medications such as diabetes, cancer, kidney
    disease and immunosuppressive drugs
  • Close contact to a person with TB disease
  • From a country with high rates of TB
  • Children under the age of 5
  • Work or live in nursing homes, clinics, hospitals, prisons, or homeless shelters
  • Malnourished, homeless, under-housed, alcohol dependent, or injection drug users

Early diagnosis is key for the control of Tuberculosis. A tuberculin skin test (TST) or Interferon-Gamma Release Assays (IGRAs) can help determine if you have been in contact with the TB bacteria. See What is a TST and What is an IGRAs for more information.

There is a 10% chance that a person with TB infection will develop TB disease. Your doctor may recommend preventative treatment in the form of medication if you test positive for TB infection.

Yes, TB is curable with the right medication. Patients take this medicine anywhere from 6-12 months to destroy all TB bacteria and cure TB disease. Failure to take your TB medication as prescribed can result in the development of drug resistant TB. If this happens, your condition may worsen.

No. Your local health department provides this medicine free of charge. A public health nurse remains in contact while you take this medication.

Yes, when taken as prescribed, TB medication is safe. As with most medicines, some people may experience side effects. Blood tests can help monitor these side effects.

Note: Tell your doctor if you do not feel well when taking your TB medication.

BCG is a live vaccine given 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

The protective effect of this vaccine decreases as a person ages and the closer they live to the equator. Because the vaccine is made from treated (attenuated) strains of TB bacteria, it may cause a person to have a false positive tuberculin skin test (TST).

People 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

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

Early diagnosis is very important in the control of tuberculosis (TB). A TST can assist in the diagnosis by confirming whether exposure to Mycobacterium tuberculosis bacteria has occurred.

You may need a TST for employment, travel or because you have been in contact with a person who has active TB. If you have been exposed to TB you may need more than one TST.

A tiny amount of test fluid called tuberculin will be injected 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. You will need to have your forearm checked 48 to 72 hours after the TST was given to measure the result and determine if the test is positive or negative.

If the TST is positive, it means that you may have been exposed to the TB bacteria. A TST 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 or cure TB.

What are IGRAs?

IGRAs are wholeblood tests that can help in diagnosing M. tuberculosis infection. IGRAs do not differentiate LTBI from tuberculosis disease. There are currently two tests licensed in Canada, QuantiFERON®-TB Gold (QFT) and T-Spot TB.

IGRAs measure the patient’s immune reactivity to M. tuberculosis, the bacterium that causes TB. White blood cells from most persons that have been infected with M. tuberculosis will release IFN-g when mixed with antigens derived from M. tuberculosis. The result is based on the amount of IFN-g produced.

What are the advantages of the IGRAs?

  • Requires a single patient visit
  • Results can be available in 2-10 days
  • Prior BCG vaccination does not cause a false positive result
  • Results not affected by most environmental Mycobacteriae
  • Results are not affected by repeated testing
  • Results are not affected by reader bias or error

What are the disadvantages of the IGRAs?

  • Cost is not covered by the OHIP
  • QuantiFERON®-TB Gold testing can only be obtained at certain laboratories
  • Please contact the laboratory for hours and availability of test
  • Limited data on the use of IGRAs to predict who will progress to TB disease in the future
  • Limited data on the use of IGRAs for:
    • Children younger than 5 years of age;
    • Persons recently exposed to M. tuberculosis;
    • Immunocompromised persons; and
    • Serial testing

When can IGRAs be considered?

  • As a confirmatory test when an individual has had a positive TST and when there is a low risk of the individual being infected with TB
  • For persons who have received BCG vaccination after infancy (1 year of age) and/or have had BCG vaccination more than once
  • For confirmation of LTBI particularly when preventative treatment is being considered
  • For persons from groups that historically have poor rates of return for TST reading

When should IGRAs not be considered?

  • For the diagnosis of active TB
  • When serial testing is indicated such as healthcare workers or other populations (e.g. corrections staff or prison inmates) with potential for ongoing exposure
  • When a live-virus vaccine has been administered unless they are both on the same day or 4-6 weeks after receiving the live vaccine

Who do I talk to if I have questions about this test or TB disease?

  • If you have any questions about IGRAs or about TB disease, talk to your doctor or call 311.

Sometimes the immune system of some individuals cannot remember past TB infection. This often occurs in the elderly and in persons whose immune system is weak. These people can have a negative reaction to the first TST. A second TST, given at least one week to as long as one year after the original TST, may produce a much greater response.

Two-step testing is recommended for:

  • People who will be re-tested periodically (i.e. healthcare workings, correctional facilities)
  • Residents (<65 years of age) and staff of long-term care homes, correctional facilities, homeless shelters and drop-in centers
  • Travelers planning a prolonged trip to an area with a high rate of TB
  • People recently immunized with an inactivated (dead virus) vaccine
  • Pregnant women
  • People who have had a previous Bacillus Calmette–Guérin (BCG) vaccination
  • People who have had a previous TST and have no record of the results or the test results were not recorded in “millimeters” of induration
  • People who have had a previous severe reaction to the TST (e.g. blistering)
  • People with extensive burns or eczema on forearm where 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

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

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

If you have any questions about the TST or TB, talk to your healthcare provider or call Halton Region Public Health by dialing 311 to speak with a nurse.