Non-infectious tuberculosis

Tuberculosis which is not contagious. It usually refers to extrapulmonary or pulmonary tuberculosis for which the sputum-based microbiological tests are negative.

Infectious period

Time period during which a person with tuberculosis is considered infectious and capable of transmitting M. tuberculosis to other persons. This period is typically defined as 12 weeks before tuberculosis diagnosis or onset of cough until the patient has been put on TB treatment and has evidence of negative microbiological tests from specimens of affected organs.

Infectious tuberculosis

Tuberculosis that is transmissible to others, i.e.contagious, usually determined by a bacteriologically positive sputum or other respiratory sample.

High tuberculosis transmission setting

Setting with a high frequency of people with undetected or undiagnosed tuberculosis, or where people with infectious tuberculosis are present and there is a high risk of tuberculosis transmission.

Household contact

Person who shared the same enclosed living space as the index case of tuberculosis for one or more nights or for frequent or extended daytime periods during the 3 months before the start of current treatment.

Exposed cohort

Groups of persons (e.g., family members, co-workers, friends, club, team or choir members, persons in correctional facilities, children in orphanages and other institutional living settings, or homeless shelter residents) who have shared the same air space with a person diagnosed with tuberculosis during the infectious period. A person in the exposed cohort is a contact.

Exposure period

Coincident period when a contact shared the same air space as a person with tuberculosis during the infectious period.


Any person who has been exposed to a person with tuberculosis.

Contact investigation

Systematic screening of people with previously undiagnosed tuberculosis or M. tuberculosis infection among the contacts of an index case of tuberculosis in the household and in comparable settings in which transmission occurs. It consists of identification, screening, clinical evaluation and/or testing, as appropriate.

Contagious (infectious) tuberculosis patient

A patient with pulmonary or laryngeal laboratory-confirmed tuberculosis who is able to spread infectious droplet nuclei containing viable M. tuberculosis while coughing, sneezing, talking or conducting any other respiratory maneuvers.


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