Tuberculosis is a bacterial disease usually affecting the lungs (pulmonary TB). Other parts of the body can also be affected, for example: lymph nodes, kidneys, bones, joints, etc. (extrapulmonary TB).
Tuberculosis can affect anyone of any age. Most often, it is associated with older people who have had previous tuberculosis exposure. Immunocompromised individuals, such as those with AIDS (or those infected with the human immunodeficiency virus, or HIV), are at increased risk.
Tuberculosis is spread through the air. When a person with infectious tuberculosis coughs or sneezes, the bacteria gets into the air. Prolonged exposure to the tuberculosis organisms is normally necessary for infection to occur. Only persons with TB in the lungs are infectious.
Tuberculosis infection may result after close contact with a person who has pulmonary tuberculosis disease. Tuberculosis infection is determined by a significant reaction to a TB skin test, absence of symptoms of tuberculosis and a normal chest X-ray. Persons with TB infection are not infectious. Tuberculosis disease is characterized by the appearance of symptoms, an abnormal chest X-ray (if pulmonary TB) and significant lab findings.
The symptoms of pulmonary TB include a low-grade fever, night sweats, fatigue, weight loss and a persistent cough. Some people may not have obvious symptoms.
Symptoms may occur as early as several weeks after infection, or it could take many years before a person would develop TB disease. The period of time for greatest risk of developing TB disease is within the first two years after infection.
A person with pulmonary TB disease may remain contagious until he/she has been on appropriate treatment for several weeks. However, a person with TB infection cannot spread the disease to others.
People with TB disease are prescribed multiple-drug therapy for at least six months. Persons newly identified with TB infection can also be treated (usually with one drug) to prevent developing disease at some later time.
The most important way to stop the spread of tuberculosis is to promptly identify and treat active cases and to preventively treat TB infections.