NTCA - Use of the QuantiFERON-TB Gold In-Tube test (QFT-GIT) for targeted tuberculosis (TB) screening at two cubicle-style hotels

This investigation demonstrates our ability to successfully operationalize field testing using QFT in a non-traditional setting.
Lisa Trieu, MPH, Douglas C. Proops, MD, MPH, Shama D. Ahuja, PhD, MPH
New York City Department of Health and Mental Hygiene, New York, NY, USA

BACKGROUND: Interferon gamma release assays (IGRA) to detect tuberculosis infection require only one patient visit and are not confounded by prior Bacillus Calmette-Guérin (BCG) vaccination, making them suitable for congregate-site testing of transient and many foreign-born populations. We report the use of QFT-GIT, an FDA-approved IGRA, for TB screening of foreign-born, high-risk residents at two cubicle-style hotels.

METHODS: In July 2010, the New York City Bureau of TB Control (BTBC) conducted targeted screening at two hotels where an HIV-infected TB patient resided during the three month period prior to starting anti-TB treatment (infectious period). The longest duration of exposure occurred at Hotel A where he stayed during most of his infectious period; he spent the last week prior to hospitalization at Hotel B. The patient reported injection drug use with fellow residents at Hotel A; he could not provide names of contacts. Residents of both hotels were predominantly Asian-born and potentially transient, which led to the decision to use QFT-GIT instead of tuberculin skin test (TST). Fliers were posted to notify residents of the screening. Screening was performed in the hotel lobby by BTBC staff, including a trained phlebotomist. Close contacts were defined as residents living on the same floor at the same time as the patient, whereas other-than-close (OTC) contacts were defined as residents living on different floors. Residents whose stay did not overlap with the patient were considered to have limited/no exposure.

RESULTS: At Hotel A, 12/17 (71%) close contacts tested positive; 3/5 (60%) OTC contacts tested positive; and 3/7 (43%) minimally exposed contacts tested positive. Given the high proportion of positive results, the investigation was expanded to Hotel B. At Hotel B, 3/7 (43%) close contacts and 2/4 (50%) OTC contacts tested positive. As of April 2011, no secondary cases have been identified.

CONCLUSION: Although a high proportion of positivity was seen at both hotels, the greatest was seen at Hotel A where the patient spent most of his infectious period. At Hotel A, QFT-positivity decreased with decreasing exposure. Due to the increased specificity of QFT-GIT over TST, positive contacts were believed to be truly infected. This investigation demonstrates our ability to successfully operationalize field testing using QFT in a non-traditional setting.