Table 1.

Selected highly exposed populations and proportion tuberculin skin test (TST) negative

Highly exposed population	Duration of exposure	Proportion TST negative (%)	References
American sailors shared cabin with seven pulmonary tuberculosis (TB) cases	6 months	19.7	8
Nurses, in 1930s New York hospital	3 years	7*	96
Household contacts in Jinan, China with average exposure 9 hr/day and proximity 30–40 cm	Not stated	31	97
Household case contacts in The Gambia sharing same bed		43	98
Gambian adults sharing room with patient		35	99
Contact at least alternate days with a patient with laryngeal TB	6 months	31	100

^*Boosting may occur in healthcare workers undergoing repeated TSTs.