title: Use of the T-SPOT.TB assay to screen latent tuberculosis infection among the TB contacts in Shanghai, China.
abstract: BACKGROUND
  There is limited information on the prevalence of latent tuberculosis infection (LTBI) and the risk factors among contacts of pulmonary TB, which might contribute significantly to TB burden and therefore become the major concern for TB control in Shanghai, China.
  
  
  METHODS
  A total of 45 diagnosed TB patients from each of 7 Shanghai districts were chosen and approximately 3 contacts per case were randomly selected. A structured 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.
  
  
  RESULTS
  Of 969 enrolled contacts, 39% were men, average age was 45 ± 19.1 years, and 76.3% were household contacts. LTBI was identified in 29.6% of subjects. Those contacting smear-positive TB patients were 2.24 times (95%CI, 1.586-3.162) more likely to develop LTBI than those otherwise; household contact significantly increased the likelihood of LTBI by 1.52 times (95%CI, 1.061-2.180). Furthermore, among household contacts, the risk of LTBI was higher in spouses and first-degree relatives and increased with age and contact duration.
  
  
  CONCLUSIONS
  A high prevalence of LTBI was observed among the TB contacts in Shanghai, highlighting the need of intervention among the household contacts and those contacting smear-positive TB patients.
authors.affiliation: Department of Epidemiology, School of Public Health, Fudan University, Shanghai 200032, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Hu
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhao
authors.forename: Edward A
authors.initials: EA
authors.lastname: Graviss
authors.forename: Weili
authors.initials: W
authors.lastname: Jiang
authors.forename: Zhengan
authors.initials: Z
authors.lastname: Yuan
authors.forename: Biao
authors.initials: B
authors.lastname: Xu
mesh_terms: D000328:Adult; D000368:Aged; D002681:China; D019411:Clinical Laboratory Techniques / Q000379:methods; D005260:Female; D006801:Humans; D059425:Interferon-gamma Release Tests / Q000379:methods; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology*; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D015995:Prevalence; D011795:Surveys and Questionnaires