title: Contact investigation in households of patients with tuberculosis in Hanoi, Vietnam: a prospective cohort study.
abstract: METHODS
  Existing tuberculosis control strategies in Vietnam are based on symptomatic patients attending health services for investigation. This approach has not resulted in substantial reductions in the prevalence of tuberculosis disease, despite the National Tuberculosis Program achieving high treatment completion rates. Alternative approaches are being considered.
  
  
  OBJECTIVE
  To determine the feasibility and yield of contact investigation in households of patients with smear positive pulmonary tuberculosis among household members of tuberculosis patients in Hanoi, Vietnam.
  
  
  METHODS
  Household contacts of patients with smear positive pulmonary tuberculosis were recruited at four urban and rural District Tuberculosis Units in Hanoi. Clinical and radiological screening was conducted at baseline, six months and 12 months. Sputum microscopy and culture was performed in contacts suspected of having tuberculosis. MIRU-VNTR molecular testing was used to compare the strains of patients and their contacts with disease.
  
  
  RESULTS
  Among 545 household contacts of 212 patients, four were diagnosed with tuberculosis at baseline (prevalence 734 cases per 100,000 persons, 95% CI 17-1451) and one was diagnosed with tuberculosis during the subsequent 12 months after initial screening (incidence 180 cases per 100,000 person-years, 95% CI 44-131). Two of these cases were culture positive for M. tuberculosis and both had identical or near-identical MIRU-VNTR strain types.
  
  
  CONCLUSIONS
  Household contacts of patients with potentially infectious forms of tuberculosis have a high prevalence of disease. Household contact investigation is feasible in Vietnam. Further research is required to investigate its effectiveness.
authors.affiliation: Woolcock Institute of Medical Research, Sydney, New South Wales, Australia. greg.fox@sydney.edu.au
authors.forename: Gregory James
authors.initials: GJ
authors.lastname: Fox
authors.forename: Nguyen Viet
authors.initials: NV
authors.lastname: Nhung
authors.forename: Dinh Ngoc
authors.initials: DN
authors.lastname: Sy
authors.forename: Luu Thi
authors.initials: LT
authors.lastname: Lien
authors.forename: Nguyen Kim
authors.initials: NK
authors.lastname: Cuong
authors.forename: Warwick John
authors.initials: WJ
authors.lastname: Britton
authors.forename: Guy Barrington
authors.initials: GB
authors.lastname: Marks
mesh_terms: D015331:Cohort Studies; D016358:Contact Tracing / Q000379:methods*; D005191:Family Characteristics; D006801:Humans; D015995:Prevalence; D015397:Program Evaluation / Q000379:methods; D011446:Prospective Studies; D014376:Tuberculosis / Q000453:epidemiology* / Q000635:transmission*; D014744:Vietnam / Q000453:epidemiology