Tuberculosis, a primarily pulmonary infection

Tuberculosis is a disease caused by a bacillus (Mycobacterium tuberculosis) that most commonly affects the lungs (pulmonary tuberculosis) but can sometimes affect other organs (extrapulmonary tuberculosis).

After being exposed to the tuberculosis bacillus, 10% of people will go on to develop the disease, with a large proportion doing so in the first few years following infection. There is therefore a distinction between so-called latent tuberculosis infection (LTBI), which presents no clinical signs and is not contagious, and active tuberculosis, which manifests with symptoms.

The risk of developing active tuberculosis following a tuberculosis infection is higher in children and immunocompromised individuals.

Tuberculosis, a Contagious Infection

Tuberculosis is an airborne disease transmitted through the dispersion of droplets of bronchial secretions from an infectious patient, particularly when they cough. Only forms of the disease affecting the respiratory system can be contagious. Among these, the most contagious forms are those in which Mycobacterium tuberculosis is detected in sputum through direct microscopic examination.

Tuberculosis Control

The rapid identification of tuberculosis cases—whether through active case finding (investigation of tuberculosis cases or targeted screening) or through spontaneous presentation for care—and their appropriate management remain the most important elements of tuberculosis control. These measures help limit the transmission of the infection in the community while preventing the development of resistance to anti-tuberculosis drugs.

Other components of tuberculosis control include:

• the treatment of latent tuberculosis infections identified in children, on the one hand, and in adults at highest risk of developing the disease, on the other;

• BCG vaccination of children most at risk of developing tuberculosis.

BCG (Bacillus Calmette-Guérin) vaccination primarily protects against severe forms of tuberculosis in children (tuberculous meningitis and miliary tuberculosis).

Infection is not always symptomatic

Infection with the tuberculosis bacillus does not necessarily cause symptoms right away. Symptoms appear only when the infection progresses to active tuberculosis, and these signs vary depending on where the disease is located. The main signs suggesting pulmonary tuberculosis are:

• a persistent cough;

• a persistent fever and night sweats;

• coughing up blood;

• weight loss;

• persistent fatigue.

In cases of extrapulmonary tuberculosis, symptoms vary depending on the location of the disease.

Tuberculosis is suspected based on clinical signs observed during a physical examination and radiological findings that vary depending on the location of the disease.
The disease is confirmed through bacteriological tests (microscopic examination, culture, and detection of Mycobacterium tuberculosis nucleic acid via PCR analysis).

Long-term management

Management of a patient with tuberculosis involves treating them with a combination of several antibiotics over an extended period, typically 6 months. Regular and consistent adherence to the treatment throughout its duration is essential, as it enables the patient to recover, limits the period during which the patient is contagious, and also prevents the development of antibiotic resistance. In cases of multidrug-resistant tuberculosis (resistance to isoniazid and rifampicin—MDR for multidrug-resistant), treatment was typically longer, lasting approximately 18 to 24 months. Highly effective treatment options now exist that no longer involve injectable antibiotics, are less toxic, and are now as short as the standard regimen for drug-sensitive tuberculosis.