Tuberculosis


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What is tuberculosis?

Tuberculosis (TB) is a contagious disease caused by bacteria called Mycobacterium tuberculosis that are spread through the air like the common cold. 

After breathing in the bacteria, a person may develop what is called a latent TB infection (LTBI), where there are no symptoms, or TB disease (also known as active TB), where there are disease symptoms. About 10% of people who are infected will become sick and develop active TB over time.

What is my risk?

For most travellers, the risk of developing LTBI and active TB is low.

Activities that can increase risk include:

  • Working in a health care setting in a country with a high rate of TB.
  • Working or being regularly exposed to people with active TB (e.g., in prisons, homeless shelters, health care settings or refugee camps).
  • Visiting friends and relatives in a country with a high rate of TB.
  • Eating or drinking unpasteurized milk and milk products (for bovine TB).

The risk of TB infection is higher for travellers with a history of active TB and those who have come into close contact with individuals having known or suspected active TB.

Those with a weakened immune system such as those with HIV, children under five years of age, those taking steroid medication or those with diabetes mellitus are at a greater risk of TB infection developing into active TB.

How is it transmitted?

  • TB is spread through the air when a person with active TB in the lungs or airways coughs, sneezes, sings or talks. Tiny droplets containing TB bacteria can stay in the air for hours.
  • Bovine TB (i.e., TB from cattle) is transmitted by eating or drinking unpasteurized, infected milk and milk products.

What are the symptoms?

  • The majority of those infected with TB do not have any symptoms. They are considered to have a latent TB infection.
  • The bacteria remain alive but inactive in the body for many years to a lifetime. The infected person is not contagious. LTBI may develop into active TB if the body’s defense (immune) system weakens. Over time, the chances of developing active TB lessen.
  • For active TB, symptoms usually include weakness or feeling very tired, weight loss, lack of appetite, chills, fever, night sweats, a bad cough that lasts longer than two to three weeks, pain in the chest, coughing up blood or sputum (phlegm).
  • Active TB bacteria usually infect the lungs but may also affect several organs (for example, lymph nodes, kidneys, etc.). Those who have active TB in the lungs or airways are infectious.
  • In more severe cases, untreated TB may lead to death.

Can tuberculosis be treated?

Both LTBI and active TB can be treated with TB drugs (antibiotics).

Where is tuberculosis a concern?

  • Tuberculosis occurs globally. It is estimated that about one-third of the world’s population has LTBI, although on average, about 10% of individuals with LTBI will eventually develop active TB.  
  • The Public Health Agency of Canada publishes a list of TB incidence rates by country.

Recommendations

Consult a health care provider or visit a travel health clinic preferably six weeks before you travel.

1. Reduce your risk:

  • Avoid close contact with people known to have active TB (in the lungs or airways) in crowded and enclosed areas with poor air circulation.
  • If you will be working in health services, prison services, homeless shelters or refugee camps, speak to your employer about infection control (personal protective gear).
  • Avoid eating or drinking any unpasteurized milk and milk products.

2. Speak to a health care provider:

  • Travellers who may be at risk of contracting TB should discuss having pre- and post-travel tuberculin skin testing.
  • In general, travellers do not need the Bacillus Calmette–Guérin vaccine. The vaccine may be considered for long term travellers to countries with a high risk of TB, for example:
    • Young children (under five years of age), who may not have access to regular tuberculin skin testing.
    • Individuals in an occupational setting who may be regularly exposed to multidrug-resistant TB.
    • Travellers who, for medical or personal reasons, may not be able to follow the recommended preventative measures against TB.

3. Monitor your health:

  • Seek medical attention if you think you may have been exposed to TB or if you have TB-like symptoms. Treatment of active TB and LTBI is an important way to prevent future infections.

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