Tuberculosis screening using a T-cell interferon-γ release assay in Japanese medical students and non-Japanese international students.

Screening of medical students and international students for tuberculosis (TB) at the time of admission is a key strategy to control and prevent the spread of infection on university campus and teaching hospitals because of the high risk of exposure to TB patients. The Mycobacterium tuberculosis antigen-specific T-cell interferon-γ release assays (IGRAs) are specific latent tuberculosis detection methods used in such groups. Currently, in Japan, there are no guidelines and no baseline data on IGRAs to evaluate the risk of TB in these high-risk groups. In order to evaluate TB risk at the time of admission in university campus and medical schools in Japan, a retrospective study was conducted. A total of 969 students (585 Japanese students and 384 international students) were screened for TB using the IGRAs at the time of admission. Eight Japanese students (0.9%) were positive for IGRAs, but none were diagnosed with active TB at the follow-up. In contrast, 30 international students (7.8%) were positive for IGRAs, including two students diagnosed with active TB during follow up. Positive ratio of IGRAs in international students was significantly higher than that of medical students at the time of admission. Here we propose a standard approach for TB screening with IGRAs at the time of admission for medical students and international students in Japan.