Transmission
Close community contact
A person who is not in the same household but shares an enclosed space, such as a social gathering place, workplace, or facility for extended periods during the day with the index patient during the 3 months before commencement of the current treatment episode.
Airborne M. tuberculosis transmission
Principal means of spreading M. tuberculosis, through which airborne droplet nuclei are suspended in airspace and subsequently inhaled by a host.
Secondary (‘second generation’) transmission
Transmission of M. tuberculosis from a secondary tuberculosis case whose index case had also been identified.
Risk of M. tuberculosis transmission
Probability of passing M. tuberculosis to another individual. This may be influenced by factors such as the frequency of contact with the source person, proximity and duration of contact, use of respiratory protection, environmental factors, and infectiousness of the source person.
Infectiousness
Probability of tuberculosis transmission from an individual with tuberculosis (usually pulmonary tuberculosis) to a susceptible individual through aerosols with droplet nuclei containing viable M. tuberculosis.
Infection-control programme (for tuberculosis)
Programme designed to control transmission of M. tuberculosis through early detection, isolation, and treatment of persons with infectious tuberculosis.
Exposure site
Location that the index patient visited during the infectious period (e.g., a school, bar, bus, or residence).
Cluster (TB)
Group of persons with tuberculosis that are linked by epidemiological or genotyping data.
Bacillary load
Quantity of M. tuberculosis bacilli present in a human body, although usually used to refer to the M. tuberculosis concentration present in a sputum sample.
