[Latent tuberculosis infection and associated risk factors among the tuberculosis contacts in one of district in Shanghai].

Objective: To investigate the prevalence of latent tuberculosis infection(LTBI) and associated risk factors among the tuberculosis(TB) contacts in Minhang District of Shanghai. Methods: A self-designed questionnaire was used to acquire socio-demographic information and to assess the degree of exposure to index cases. LTBI screening was performed by T-SPOT.TB assay. Pearson chi-square test and Logistic regression analyses were used to identify the risk factors associated with LTBI among the TB contacts. Results: A total of 137 contacts from 59 mycobacterial (culture) positive pulmonary TB patients were enrolled in this study. In these contacts, there were 54 men and 83 women, with the average age of 42. LTBI was identified in 20% (27/137) of these contacts. Several risk factors were found by logistic analyses in this study. The worse the ventilation in the exposure location was, the more likely to develop LTBI. Contacts aged more than 60 (42.1%) were 3.9 times more likely to develop LTBI than those aged less than 60 (16.1%). Individuals in contact with TB patients for more than 40 h/week(25.8%) had a 4.2 times risk of LTBI as compared to those for less than 40 h/week(6.8%). Conclusion: The prevalence of LTBI was 20% among the TB contacts in this study, highlighting the need of TB screening and intervention among TB contacts.