Evaluation of two-step tuberculin testing in a Massachusetts correctional facility

Area of Science:

• Public Health
• Infectious Disease Epidemiology
• Occupational Health

Background:

• Tuberculosis (TB) infection control in correctional facilities is crucial.
• Accurate identification of TB infection at admission is essential for preventing outbreaks.
• Annual retesting aims to estimate TB conversion rates.

Purpose of the Study:

• To evaluate the feasibility and utility of two-step tuberculin skin testing for newly admitted inmates.
• To improve the identification of inmates with tuberculosis infection upon admission.
• To obtain more accurate estimates of TB conversion rates through annual retesting.

Main Methods:

• A two-step tuberculin skin testing protocol was implemented for newly admitted inmates.
• A second skin test was administered one week after the first for individuals with negative initial results.
• Data were collected from inmates admitted to the Addiction Center between January and May 1994.

Main Results:

• Out of 628 admissions, 51 inmates (8%) reported a history of positive skin tests.
• The initial tuberculin skin test yielded positive results in 12 out of 570 read tests (2.1%).
• The second tuberculin skin test identified an additional 5 positive results out of 510 read tests (1%).

Conclusions:

• Two-step tuberculin skin testing identified 40% more inmates with positive results compared to single testing.
• The method's utility is high, but successful implementation depends on achieving a high initial skin test reading rate (99% in this study).
• Serial testing is expected to enhance TB identification in correctional facilities, but should be deferred until initial reading rates improve across facilities.