TB: What you should know

Zoomer | August 6th, 2007

Tuberculosis was once again in the news with reports of a passenger diagnosed with the disease on a flight from Frankfurt-to-Detroit. And although the Centers of Disease Control (CDC) spokeswoman said that the risk was low that other passengers may have been infected, health officials were seeking to contact people seated near the sick passenger so they can be tested for tuberculosis as a “cautionary move.”

It brings to mind another case of an infected passenger, Andrew Speaker, who became headline material when he chose to travel by airplane from the United States to Europe in order to be married. He had been diagnosed with TB in the United States but claims he did not know it was of a type called “extensively drug resistant” until he was in Rome. Even so, he boarded a commercial flight to return to the US – and flew through Canada on the way.

According to a recent World Health Organization survey, multidrug-resistant tuberculosis (MDR-TB) is at the highest rates ever with nearly half a million new cases of MDR-TB a year, which is about 5 per cent of nine million new TB cases of all types.

TB: What you should know
In order to become infected with tuberculosis, an individual must breathe the TB bacteria into his or her lungs. The bacteria are spread only through coughing and then direct inhalation – it is not transmitted through things like handshaking or sharing dishes. Although this can happen through casual contact, it is much more likely in the case of prolonged contact with someone who has the disease.

Often the immune system is able to kill the tuberculosis bacteria. In some cases, however, the individual’s immune system is not able to respond, and then the infection can become tuberculosis disease. This most commonly occurs in the first 2 years after exposure.

If an adult has the tuberculosis infection he or she may progress to the disease if their immune system is weakened. This happens in about ten per cent of cases (after the initial 2 year period).

The disease itself is a serious disease which attacks the lungs and can spread to other parts of the body. TB in the lungs may cause:
• a bad cough that lasts longer than 2 weeks
• pain in the chest
• coughing up blood or sputum (phlegm)
• weakness or feeling very tired
• weight loss
• no appetite
• chills
• fever
• night sweats

With most strains of the disease, antibiotics can be an effective treatment. Antibiotics can be given in the case of tuberculosis infection to reduce the chances of full-blown tuberculosis disease. In the case of tuberculosis disease, the treatment is lengthy – 6 months or longer, taking more than one antibiotic.

Risk factors
The Public Health Agency of Canada highlights the following risk factors for tuberculosis:
• people born in or travelling to countries where TB is common
• people with an Aboriginal background
• homeless people
• alcoholics
• people who work or live in a prison or jail
• people over 65 years of age
• people who work with any of the above high-risk groups (i.e., health care workers)

The risk of getting drug-resistant TB are still very low – in the United States there were only 49 cases from 1993 to 2006. It’s most likely to develop in individuals with TB who do not take their medication properly – or from being exposed to an individual who has the disease.

Testing
If a person has TB infection, a skin test will often indicate the presence of TB bacteria in the bloodstream. TB disease, however, is most commonly diagnosed through a chest x-ray, or by testing phlegm. A positive skin test does not always indicate TB, however, as some vaccines and other related bacteria in the system will also trigger a positive skin test. It also takes 2 to 12 weeks for the test to become positive after a person has been exposed to the TB bacteria.

Sources: World Health Organization; Associated Press; Public Health Agency of Canada.

This was updated on March 18, 2009.