# Monday, October 6, 2008
                 

Ontario public health officials are trying to contact 27 people who have been exposed to tuberculosis from a passenger on a bus traveling from Toronto to Windsor this past August. The passengers are being publicly urged to contact their local health units in order to be tested for TB as a safeguard. As the TB bacteria cannot be detected for at least 3 weeks following exposure, people may not be aware that they could potentially become ill. The risk that other passengers may have been exposed is low, but it is still necessary to be tested to determine if anyone else has caught the disease.

Approximately 1600 new cases of TB are reported in Canada every year, so the risk of developing the disease is relatively low. However, it can have serious health risks, so it is important for Canadians to recognize the symptoms as well as minimize the risk of becoming infected. TB is transmitted by frequent exposure to someone that has active tuberculosis; the bacterium is spread via sneezing, singing, coughing, etc. It is not as contagious as other diseases such as influenza or the chicken pox.

Most people can be exposed to TB bacteria and not develop the disease. It is possible for the immune system to effectively kill the germs. If this doesn't happen the bacteria can remain alive in the body which is called TB infection. Someone with TB infection will show no symptoms and not fall ill; they are also at no risk of spreading the disease. TB infection occurs when the immune system cannot stop the bacteria from growing; this risk is highest within 2 years of becoming infected. Approximately 10% of people will become infected with tuberculosis within their lifetime.

The symptoms of tuberculosis in the lungs are:

• bad cough that lasts longer than 3 weeks
• pain in the chest
• feeling very weak and/or tired
• coughing up blood and/or sputum
• loss of appetite
• fever and/or night sweats

A simple skin test can determine whether or not a person has a TB infection. This is accomplished by a very small amount of non-infectious TB protein being injected under the surface of the skin; a hard swelling will develop within 48-72 hours if the person is infected. At this point the health care provider will probably recommend antibiotic treatment in order to prevent the infection from developing into TB disease. Additional tests as well as chest x-rays may be needed in order to determine whether or not TB disease is present.

For those people who have TB disease it is extremely important to be treated as soon as the disease has been determined. A course of antibiotics for a minimum of 6 months is needed in order to kill all of the TB bacteria. Finishing the course of treatment is vital in order to prevent the risk of developing a strain of the disease that will be drug resistant, which is harder as well as more expensive to treat. As well, people who do not finish the treatment also pose a risk of spreading TB to others.

People with a weakened immune system are more at risk of developing TB infection and/or disease. People who have HIV/AIDS are 50-170 times more likely to develop TB disease; therefore this population group should always be tested for TB. Conversely, people who test positive for TB infection and/or disease should also get tested for HIV in order to help the physician determine the best course of treatment. Other populations that have an increased risk for TB infection are anyone:

• who has come into close contact with someone who has or is suspected to have active TB
• with a history of active TB and/or has had an x-ray suggesting that they had TB in the past but did not receive treatment
• who is living in an Aboriginal community that has a high rate of TB infection and/or disease
•  who is living or working at a long-term care facility, correctional facility
• who has had an organ transplant and is being treated with immunity-suppressing drugs
• who has a lung disease known as silicosis
• who has chronic lung failure and requires dialysis
• who has cancer of the head and/or neck
•  who has been infected with the TB bacteria within the past 2 years
•  who has had a chest x-ray that shows signs of old TB
• who is being treated with glucocorticoids
• who is receiving treatment with tumor necrosis factor alpha inhibitors (for auto-immune disorders such as rheumatoid arthritis)
• who has any type of diabetes
• who is underweight with a body mass index of under 20
• who smokes one pack of cigarettes or more per day
• who is under five years old when first infected with the bacteria

If you suspect that you have been exposed to someone that has tuberculosis, make an appointment with your health care provider for testing. You can also visit The Lung Association website for more information regarding tuberculosis.

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