Pulmonary tuberculosis (TB) is a common worldwide infection and a medical and social problem causing high mortality and morbidity, especially in developing countries.
Tuberculosis, also known as consumption, spread widely as an epidemic during the 18th and 19th centuries in North America and Europe. After the discovery of antibiotics like streptomycin and especially isoniazid, along with improved living standards, doctors were better able to treat and control the spread of TB.
M. tuberculosis is carried in airborne particles, called droplet nuclei, are produced when persons with pulmonary or laryngeal TB cough, sneeze, speak, or sing.
The particles, which measure 1–5 µm in size, can be kept airborne by normal air currents for prolonged periods of time, resulting in dispersion throughout a room or building. Transmission occurs when a person inhales droplet nuclei containing M. tuberculosis, and the droplet nuclei traverse the mouth or nasal passages, upper respiratory tract, and bronchi to reach the alveoli of the lungs.
Pulmonary TB frequently develops slowly, without a definite date of onset. Patients with active pulmonary TB may be asymptomatic, have mild or progressive dry cough, or present with multiple symptoms including low-grade fever, anorexia fatigue, night sweats, and weight loss that may persist for weeks to months.
TB can be active or latent (inactive). Active TB is sometimes referred to as TB disease. This is the type of TB that is contagious.
Pulmonary tuberculosis
