title: Latent tuberculous infection in household contacts of multidrug-resistant and newly diagnosed tuberculosis.
abstract: Differences in the prevalence of latent tuberculous infection (LTBI) and tuberculosis (TB) disease among contacts of patients with multidrug-resistant TB (MDR-TB) and drug-susceptible TB are not well understood.
  
  
  
  To compare the prevalence of tuberculin skin test (TST) positivity in household contacts of patients with MDR-TB and in contacts of patients never previously treated for TB ('new TB').
  
  
  
  Consecutive patients with MDR-TB and their household contacts at nine urban district clinics in Viet Nam were screened for TB and LTBI, and followed up for 6 months. LTBI was defined as a TST result of at least 10 mm.
  
  
  
  A total of 167 patients with TB and their 337 household contacts were recruited. A total of 167/180 (25.8%) contacts of new TB patients and 60/147 (40.8%) contacts of MDR-TB patients were TST-positive (odds ratio [OR] 2.0, 95%CI 1.3-3.2). Contacts of MDR-TB patients were more likely to have baseline chest radiograph findings consistent with TB (OR 2.6, 95%CI 1.4-5.0).
  
  
  
  Contacts of MDR-TB patients have a high risk of developing TB. Measures to reduce Mycobacterium tuberculosis transmission and accelerate the detection of disease among high-risk contacts should be prioritised to curb the MDR-TB epidemic.
authors.affiliation: University of Sydney, Camperdown, New South Wales, Australia.
authors.forename: G J
authors.initials: GJ
authors.lastname: Fox
authors.affiliation: University of Sydney, Camperdown, New South Wales, Australia.
authors.forename: N T
authors.initials: NT
authors.lastname: Anh
authors.affiliation: National Lung Hospital, Hanoi, Viet Nam.
authors.forename: N V
authors.initials: NV
authors.lastname: Nhung
authors.affiliation: University of Sydney, Camperdown, New South Wales, Australia.
authors.forename: N T
authors.initials: NT
authors.lastname: Loi
authors.affiliation: National Lung Hospital, Hanoi, Viet Nam, International Union Against Tuberculosis and Lung Disease, Paris, France.
authors.forename: N B
authors.initials: NB
authors.lastname: Hoa
authors.affiliation: University of Sydney, Camperdown, New South Wales, Australia, National Lung Hospital, Hanoi, Viet Nam.
authors.forename: L T
authors.initials: LT
authors.lastname: Ngoc Anh
authors.affiliation: Hanoi Medical University, Hanoi.
authors.forename: N K
authors.initials: NK
authors.lastname: Cuong
authors.affiliation: National Tuberculosis Programme, Can Tho City, Viet Nam.
authors.forename: T N
authors.initials: TN
authors.lastname: Buu
authors.affiliation: University of New South Wales, Kensington, New South Wales, Australia.
authors.forename: G B
authors.initials: GB
authors.lastname: Marks
authors.affiliation: McGill University, Montreal, Quebec, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Menzies
mesh_terms: D000328:Adult; D015331:Cohort Studies; D016358:Contact Tracing; D005191:Family Characteristics; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D055985:Latent Tuberculosis / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis / Q000453:epidemiology* / Q000635:transmission; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis / Q000635:transmission*; D014744:Vietnam / Q000453:epidemiology; D055815:Young Adult