Tuberculosis

Tuberculosis is an infectious disease caused by the microbe Mycobacterium tuberculosis. It can develop quickly following the 1^st contact with this microbe. It can also appear several years later.

Over the past 30 years, tuberculosis has been on the decline in Québec. Thanks to treatment and care for people with the disease, the number of new cases in Québec is low, fluctuating between 200 and 280 annually. Cases of tuberculosis in Québec are among the lowest in Canada. They are also lower than those of many industrialized countries.

There are 2 types of tuberculosis:

• Latent tuberculosis infection
• Active tuberculosis

Latent tuberculosis infection is a state in which a person is infected by the tuberculosis germ but the microbe remains inactive. The infected person shows no symptoms. Latent tuberculosis infection is not contagious. A preventive antibiotic treatment can be recommended for a person with this type of tuberculosis to prevent the disease from becoming active in the future. In 90% of people infected, the infection remains latent and will not evolve into active tuberculosis.

Active tuberculosis is a condition in which tuberculosis microbes are active and lead to symptoms. This indicates that an infected person’s immune system has been unable to adequately defend itself against the bacteria. The disease most often develops in the lungs, but other parts of the body, such as the lymph nodes, kidneys and bones, can also be affected.

People with latent tuberculosis infection do not feel sick. They have no symptoms.

Symptoms of active tuberculosis depend on the part of the body infected. When tuberculosis develops in the lungs (pulmonary tuberculosis), its main symptoms are:

• Cough that lasts longer than 3 weeks, often accompanied by phlegm
• Fever
• Significant fatigue
• Decrease of appetite
• Night sweats
• Weight loss

Latent tuberculosis infection is not contagious.

Active tuberculosis can be contagious depending on the part of the body affected. Pulmonary tuberculosis is often contagious. When other organs or tissues in the body, such as kidneys and bones, are infected, the disease is not contagious.

When a person with pulmonary tuberculosis coughs or sneezes, microbes spread into the air. Other people can then get infected by inhaling these germs.

People treated for tuberculosis generally stop being contagious a few weeks after the beginning of their treatment. The doctor determines the end of the infectious period according to specific criteria and in collaboration with public health professionals.

Treatment for latent tuberculosis infection

A preventive antibiotic treatment for a few months can be recommended to prevent the disease from developing later.

Treatment for active tuberculosis

Tuberculosis is treated with several medicines that must be taken regularly over several months. Most people with tuberculosis heal when they take their medicines as prescribed. Once treated, tuberculosis is no longer contagious.

In Québec, tuberculosis is a disease that requires mandatory treatment.

People with the disease must sometimes be hospitalized for a short period. They can then continue their treatment at home and resume their normal activities.

Screening of latent tuberculosis infection

Screening of latent tuberculosis infection can be performed with 2 tests. The most common is the tuberculin skin test (TST), which consists of an injection under the skin. The interferon gamma release assay is less common and requires a blood sample.

The TST helps determine:

• If you have already been in contact with the tuberculosis microbe.
• If you are at risk of developing the disease later.

The TST requires 2 health appointments:

• In the 1^st appointment, a healthcare professional injects a small quantity of a substance called tuberculin under the skin of your arm.
• In the 2^nd appointment, which is 48 to 72 hours later, the healthcare professional analyzes the reaction on your arm to determine if the result is positive or negative.

If the healthcare professional determines that the result is positive, he or she may recommend additional tests, such as a chest X-ray and a medical exam. A preventive treatment could also be recommended.

For more information about this screening, consult a healthcare professional or call Info-Santé 811.

Vaccination

There is a vaccine for tuberculosis. It is called BCG. However, it is not widely distributed in Canada and not recommended for the general public in Québec. It is mostly used to lower the risk of developing a very severe type of tuberculosis in young children in settings where transmission rates of the disease are very high.

Anyone can get tuberculosis. Most cases of tuberculosis in Québec are diagnosed in people who have lived or travelled in regions of the world where tuberculosis is still very common, such as some countries in Asia or Africa.

Montréal, Montérégie and Laval have the highest number of reported cases of tuberculosis in Québec.

The transmission of tuberculosis is most common in Nunavik compared to other regions. It is the place in Québec with the highest rates of tuberculosis, even though the number of cases is relatively low. Social inequalities and housing conditions are factors that might contribute to the situation.

Other factors increase the risk of exposure to tuberculosis, including:

• Living under the same roof as a person with the disease. People who are in constant and prolonged contact with someone with the disease, such as a work colleague, are at risk of getting infected with tuberculosis.
• Being homeless.
• Having spent time in a detention centre.

In people already exposed to tuberculosis, and who have latent tuberculosis infection, a weakening of the immune system can lead to the development of active tuberculosis. Such is the case for people infected with HIV, for example.

In Québec, tuberculosis is a mandatory reportable disease. Laboratory workers and doctors who detect a case of tuberculosis are required to inform public health officials.

If you have been in contact with someone with tuberculosis and are concerned for your own health, call Info-Santé 811.