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In the 1940s, tuberculosis was considered to be a fatal illness, with over 7 000 cases a year reported in Canada. This number has now dwindled to some 2 000 cases a year, with 400 in Quebec alone. The bacterium is estimated to have infected one third of the earth's population. Canada currently has one of the lowest tuberculosis rates in the world, thanks to disease control, new drugs, public health measures, education and improved living conditions.

TB disease (active)

People with (active) TB disease are potentially contagious and through speech, coughing or sneezing, can spread infectious bacilli that are carried in the ambient air in the form of tiny droplets. It should be noted that only individuals with pulmonary tuberculosis are considered contagious. A weakened immune system may allow multiplication of the bacilli and eventually produce classic TB symptoms.

TB infection (latent)

A small percentage of those who come in contact with people suffering from (latent) TB infection will inhale these airborne droplets, and will themselves be stricken with TB infection in its latent form. Only 10% of those who are infected with tuberculosis will develop (active) TB disease during the course of their lives.

Carriers of (latent) TB infection are not contagious and develop no symptoms. They do not represent a risk for themselves or for others because they are neither ill nor contagious. Furthermore, a preventive treatment is available that can significantly reduce the chances of the latent infection developing into active TB.


Tuberculosis is a contagious disease, caused by the Mycobacterium tuberculosis, also known as Koch’s bacillus. The latter usually establishes itself in the lungs, creating cavities that end up destroying the lung tissue. It can also lodge in various parts of the body like the ganglia, kidneys, skin, bones and reproductive system. Contamination by Koch’s bacillus mainly occurs through the respiratory tract (airborne transmission).

Persons at risk

Anyone having extended contact with a person suffering from (active) TB disease runs the risk of becoming infected with the mycobacteria.

HIV/AIDS-infected individuals are more likely to develop an (active) TB disease should they get infected with the bacilli. People who live in distressed social environments with poor sanitary conditions are also more exposed to the disease.

Signs and symptoms

People with tuberculosis have one or several persistent symptoms, which may sometimes be confused with other illnesses:

  • Coughing that lasts more than 3 weeks
  • Fever
  • Loss of energy
  • Loss of weight
  • Night sweats
  • Chest pain
  • Loss of appetite
  • Traces of blood in the sputum

A person who coughs for several weeks for no apparent reason, such as a cold/flu/allergy/asthma and is more tired than usual, should consult a doctor.


The doctor will establish a diagnosis after examining the person’s medical history, assessing his/her general health, taking into account the symptoms and the point at which they appeared, studying a lung X-ray and performing lab tests designed to detect the presence of Koch’s bacillus (KB) in the sputum.

The tuberculin skin test based on the Mantoux method calls for the injection of a product called PPD which is used to screen for TB infection.


Since the introduction of effective antibiotics in the fight against tuberculosis, its evolution and prognosis have improved considerably. Treatment is designed to totally eliminate the bacilli.

The treatment of (active) TB disease takes place over a six-month period and usually involves taking four antibiotics:

  • INH=Isoniazid
  • RIF=Rifampin
  • PZA=Pyrazinamide
  • EMB=Ethambutol

If these drugs are taken as prescribed by the doctor, the tuberculosis quickly becomes non-contagious and the individual is completely cured by the end of the treatment. It is very important that the person suffering from tuberculosis follow the entire treatment, i.e. that he/she take the prescribed drug combination, not skip any doctor’s appointments and submit to the follow-up examinations in order to assure proper recovery.

Without patient cooperation, the best drugs remain ineffective and the disease is bound to gain some ground at the patient’s expense. Furthermore, poor compliance raises the risk of contagion.

Quickly notify the doctor if you experience any discomfort when taking your medication.

People with (latent) TB infection receive a treatment referred to as prophylactic, in order to prevent the disease from developing. Isoniazide (INH) is the drug of choice and must be taken daily for a period of 6 to 12 months. This preventive treatment is designed to destroy the inactive microorganisms that have not yet begun to take their toll but might become active a few years later.

Tuberculosis is a disease that can be treated and cured if the patient methodically adheres to the advice provided by the team of healthcare professionals.

It should be noted that the Montreal Chest Institute is a medical facility focussing on respiratory health, including tuberculosis.

  • Vaccination

Did you know that

The Quebec Lung Association offers direct services to the population. For more information, visit our Patient Resources section.