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Tuberculosis
January 2010
Tuberculosis
What is Tuberculosis?
Tuberculosis (TB) is a contagious bacterial disease. After breathing in the bacteria, 5% to 10% of people will become sick and develop active TB overtime and usually in the lungs.
Cause
TB is caused by Mycobacterium tuberculosis, bacteria which are spread through the air, like the common cold.
After breathing in the bacteria, a person may develop a latent TB infection (LTBI) or active TB disease.
In LTBI, the bacteria remain alive but inactive in the body. Therefore, the infected person is not sick, does not show symptoms and is not contagious. LTBI may develop into active TB disease if the body’s defense (immune) system weakens.
In the active TB stage, a person is sick and shows symptoms of the TB disease. Active TB bacteria usually infect the lungs or airways but may also affect several organs (i.e.: lymph nodes, kidneys, etc). Those who have active TB in the lungs or airways are infectious.
For most travellers, the risk of developing LTBI and active TB is low.
Activities which 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 (i.e.: in prisons, homeless shelters, 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).
Travellers with increased risk of TB infection include those with a history of active TB and those who have come into close contact with individuals known or suspected of active TB
Travellers are also at greater risk of TB infection developing into TB disease if they have a weakened immune system such as those with HIV, children under 5 years of age, treatment with steroids, diabetes mellitus.
Severity
In about 90-95% of those infected with TB, there are no symptoms. This is called latent TB infection (“LTBI”) where the bacteria remain inactive in the body for many years to a lifetime. Over time, the chances of developing active TB lessen.
Among the other 5% to 10% infected, TB disease will develop, most likely in the lungs (pulmonary TB). Without proper treatment, TB can be fatal.
Prevention
- Avoid exposure to people known to have untreated TB disease in crowded and enclosed areas with poor air circulation. These areas can include some hospitals, prisons, homeless shelters and refugee camps in some low-income countries.
- A vaccine for TB exists, although it is not generally recommended for Canadian travellers.
Treatment
All TB can be treated with antibiotic drugs for at least 6 months.
Symptoms
- There are no symptoms for LTBI. However, LTBI can be determined with a tuberculin skin test (TST) or one of the new blood tests known as interferon-gamma release assays
- For active TB, symptoms usually include swollen and sore lymph glands, weakness or feeling very tired, weight loss, lack of appetite, chills, fever, night sweats
- For active TB in the lungs and airways (pulmonary TB), symptoms usually include a bad cough that lasts longer than three weeks, pain in the chest, coughing up blood or sputum (phlegm)
- In more severe cases, untreated TB may lead to death
Transmission
- Tuberculosis is spread through the air when a person with active pulmonary TB 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 through ingestion of unpasteurized, infected milk and milk products.
Where is Tuberculosis a concern?
- Tuberculosis occurs globally. It is estimated that one-third of the world’s population has LTBI, although only about 5-10% will eventually develop symptoms.
- The World Health Organization estimates that there were over 9 million new cases of TB worldwide in 2007. More than half of the new cases occurred in Asia and a third in Africa.
- The top five countries for new cases in 2007 were India, China, Indonesia, Nigeria and South Africa.
- A map of TB risk areas is available from the website of the Public Health Agency of Canada (PHAC)
Related Travel Health Notices
None.
Recommendations for Travellers
- Reduce your risk:
- Avoid exposure to people known to have active pulmonary TB in crowded and enclosed areas with poor air circulation;
- If you are travelling to work in health services, prison services, homeless shelters, or refugee camps, speak to someone in infection control or occupational health about personal protective gear;
- Avoid eating or drinking any unpasteurized milk and milk products
- Consult a physician:
- Travellers who may be at risk of contracting TB should discuss having pre- and post-travel tuberculin skin testing (“TST”)
- Travellers who may be at high risk of contracting TB should discuss the possibility of getting vaccinated.
- Monitor your health:
- Seek medical attention immediately if you think you may have been exposed to TB, or if you have TB-like symptoms
- Treatment of active TB infection and sometimes LTBI is an important way to prevent future infections
Don't Forget…
- Consult a doctor, nurse or health care provider or visit a travel health clinic at least six weeks before you travel.
- What to do if you get sick when you are travelling.
- What to do if you get sick after you return to Canada.
- Know what vaccines you need and when to get them.
Other Related Information
- Public Health Agency of Canada (PHAC) – Fact Sheets: Tuberculosis
- PHAC – Tuberculosis Prevention and Control
- Committee to Advise on Tropical Medicine and Travel (CATMAT) – Risk Assessment and Prevention of Tuberculosis among Travellers
- Health Canada – It’s Your Health
- World Health Organization (WHO) – Fact Sheets: Tuberculosis
- WHO – Global Tuberculosis Control (2009)
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