title: [Prevalence and risk factors of latent tuberculosis infection in close contacts of tuberculosis patients among non-resident populations in Shanghai, China].
abstract: OBJECTIVE
  To investigate the prevalence of latent tuberculosis (TB) infection (LTBI), and to identify the risk factors in close contacts of pulmonary TB patients among non-resident population in Shanghai.
  
  
  METHODS
  The study subjects were the close contacts of pulmonary TB patients among non-resident populations in Xuhui, Minhang and Songjiang Districts in Shanghai from 2013 to 2014.Questionnaire interview was applied to collect the socio-demographics, TB-related clinical and TB exposure information from the enrolled TB patients and their close contacts. The T-SPOT.TB test was used to identify the infection of M. TB. LTBI was defined as a positive T-SPOT.TB result inthe absence of signs and symptoms related to TB.
  
  
  RESULTS
  In total, 182 pulmonary TB patients and 360 close contacts were enrolled in the present study. The mean age of the close contacts was (34±14) years(range, 2-83 years), including 160 men and 200 women. The T-SPOT.TB test and TB related examination revealed that 17.2% (62/360) of the close contacts were latently infected with M. TB. All the LTBI subjects were household contacts (χ(2)=16.814, P<0.001). In multivariate analysis, the risk of LTBI was statistically associated with the presence of TB symptoms of the index case (OR=2.696, 95%CI: 1.060-6.857) and duration of exposure (OR=1.007, 95%CI: 1.001-1.014); whereas there were no statistically significant associations among age, gender, diagnostic delay of index case, environment of contact place and the risk of LTBI among the studied close contacts.
  
  
  CONCLUSIONS
  The prevalence of LTBI in close contacts of pulmonary TB patients among non-resident population in Shanghai is 17.2%.Contact with patients with TB symptoms and longer duration of exposure might increase the risk of LTBI.
authors.affiliation: Department of Epidemiology, School of Public Health, Fudan University, the Key Laboratory on Public Health Safety Ministry of Education, Collaborative Innovation Center of Social Risks Governance in Health, Shanghai 200032, China.
authors.forename: Jiangjun
authors.initials: J
authors.lastname: Xu
authors.forename: Yi
authors.initials: Y
authors.lastname: Hu
authors.forename: Weili
authors.initials: W
authors.lastname: Jiang
authors.forename: Jianjun
authors.initials: J
authors.lastname: Hong
authors.forename: Lihong
authors.initials: L
authors.lastname: Tang
authors.forename: Meixia
authors.initials: M
authors.lastname: Yang
authors.forename: Xin
authors.initials: X
authors.lastname: Shen
authors.forename: Biao
authors.initials: B
authors.lastname: Xu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D057210:Delayed Diagnosis; D005190:Family; D005260:Female; D006801:Humans; D007223:Infant; D055985:Latent Tuberculosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014397:Tuberculosis, Pulmonary; D055815:Young Adult