One reason is to determine whether persons are infected with M. tuberculosis . Persons who are infected with M. tuberculosis may be given treatment of latent infection to prevent them from developing TB disease. Another reason is to determine whether persons have TB disease . Persons who have TB disease are given treatment for the disease. Whether testing focuses on finding infection or finding disease depends on the setting.
Flexibility is needed in defining high-priority groups for testing.
The changing epidemiology of TB indicates that the risk for TB among groups currently considered high priority may decrease over time, and groups currently not identified as being at risk subsequently may be considered as high priority. Testing for Latent TB Infection Testing for latent TB infection is done with the Mantoux tuberculin skin test. Testing should be targeted at either of two groups. In some circumstances, testing for TB disease with chest radiographs or sputum smears may be more appropriate than testing for infection with the Mantoux tuberculin skin test. For example, chest radiography may be the best method in jails or homeless shelters, where the time required to give skin tests to large numbers of transient persons and to read results makes testing for infection impractical.