Diagnosis of Latent Tuberculosis Infection

Abstract

For 2015, tuberculosis (TB) incidence in the United States has plateaued at 3.0 per 100,000. This remains the lowest case rate since recording started. On the global level, although the TB epidemic is larger than previously estimated, TB deaths and incidence rate continue to fall. For both low and high incidence countries, accelerating the decline in TB incidence towards elimination goals requires that more emphasis be placed on strengthening systems for detection and treatment of latent TB infection (LTBI) in addition to improving TB care globally. Here, we review the tuberculin skin test and gamma interferon release assays currently available for the detection of LTBI.

FIGURE 1

Distribution of reactions to 5 TU of PPD among Alaskans tested in 1962. Reprinted with permission from Archives of Environmental Health (6).

FIGURE 2

Distribution of reactions to 5 TU of PPD among white Navy recruits from the state of Georgia, with estimate of proportion infected with M. tuberculosis. Reprinted with permission from The Tuberculin Test: Supplement to Diagnostic Standards and Classification of Tuberculosis and Other Mycobacterial Diseases (7).

FIGURE 3

Schema of probable distribution of reactors to 5 TU of PPD in the New York City metropolitan area.

FIGURE 4

Schematic representation of three booster effect possibilities. (See text for discussion.)