Abstract: Objective To investigate the situation of tuberculosis (TB) morbidity and infection among applicants for living abroad in Beijing, and to fill this knowledge gap which will be used for establishing an effective monitoring and management system at the ports, thereby preventing TB transmission across national boundaries. Methods A retrospective analysis was conducted. The data used for analysis were from 15 598 immigration applicants to the United States (US) who received TB screening at Beijing International Travel Health Care Center from July 2008 to June 2013. Tuberculin skin testing (TST) or interferon gamma release assays (IGRAs) was performed on 2488 children aged 2-<15 years; chest X-ray (CXR) was taken on 13 110 applicants aged 15 years and older, sputum smear and culture were performed on 401 applicants with a CXR result suggesting pulmonary TB (PTB) or suspected PTB, strain identification of Mycobacterium tuberculosis (Mtb) and drug susceptibility testing (DST) were done using the strains isolated by culture. Results Accordance to the updated guidelines for using IGRAs to detect Mtb infection issued by US CDC in 2010 and the Chinese diagnostic criteria for PTB, the following results were obtained: (1) Active PTB: among 401 applicants with abnormal CXRs who were identified from 13 110 applicants aged 15 years and older, 15 PTB cases were detected (114.42 per 100 000), including 11 bacteriologically confirmed cases and 4 bacteriologically-negative cases (83.91 and 30.51 per 100 000, respectively). (2) Inactive TB: 386 inactive TB were found among applicants aged 15 years and older, the rate was 2944.32 per 100 000. (3) Latent TB infection (LTBI) in children: among 2488 children aged 2-<15 years, 444 children were diagnosed as LTBI with normal CXRs, including 423 were TST≥10 mm and 21 were IGRAs positive. The rate of LTBI among children was 17 845.66 per 100 000. (4) There were 2 close contacts of TB patients among the applicants aged 15 years and older. (5) Bacteriological examinations: 3 sputum specimens were collected from each of 401 applicants with abnormal CXRs and aged 15 years and older, smear and culture were performed, of which were detected: 4 cases were smear-positive and culture-positive (S+C+), 7 cases were smear-negative but culture-positive (S-C+) and 390 cases were smear-negative and culture-negative (S-C-). All of the 11 culture-positive cases were identified as Mtb, 9 of them were confirmed by DST as susceptible TB while other 2 were drug-resistant TB (1 was multidrug-resistant TB and 1 was poly drug-resistant TB). (6) The active TB prevalence reached a peak for the age group 60 years and older (371.52 per 100 000), followed by the age group 15-<30 years (145.88 per 100 000).  Conclusion People with abnormal CXRs and aged 15 years and older should be considered as the target populations of TB control in the immigration health check-up, and those with TST≥10 mm or IGRAs positive and aged 2-<15 years should not be neglected either.

Key words: Tuberculosis, pulmonary/prevention &, control, Transients and migrants, Beijing city