Transmission

• M. tuberculosis is carried in airborne particles called droplet nuclei that can be generated when persons who have pulmonary or laryngeal TB disease cough, sneeze, shout, or sing. These particles, about one to five microns in diameter, can remain in the air for several hours, depending on the environment and ventilation (See Module 7 for more information).


• Transmission begins with the inhalation of infectious aerosols containing M. tuberculosis. This generally occurs indoors, since ventilation removes droplet nuclei from a contaminated space and direct sunlight rapidly kills M. tuberculosis.