title: A four-year nationwide molecular epidemiological study in Estonia: risk factors for tuberculosis transmission.
abstract: METHODS
  Estonia has a high proportion of multidrug-resistant tuberculosis (MDR-TB). It is important to link molecular and epidemiological data to understand TB transmission patterns.
  
  
  OBJECTIVE
  To use 24-locus variable numbers of tandem repeat (VNTR) typing and national TB registry data in Estonia from 2009 to 2012 to identify the distribution of drug resistance patterns, Mycobacterium tuberculosis isolate clustering as an index for recent transmission, socio-demographic and clinical characteristics associated with recent transmission, and the distribution of transmission between index and secondary cases.
  
  
  METHODS
  A retrospective nationwide cross-sectional study.
  
  
  RESULTS
  Of 912 cases with isolate and patient information, 39.1% of isolates were from the Beijing lineage. Cluster analysis identified 87 clusters encompassing 69.1% of isolates. The largest cluster comprised 178 isolates from the Beijing lineage, of which 92.1% were MDR- or extensively drug-resistant TB (XDR-TB). Factors associated with recent transmission were polyresistant TB, MDR- and XDR-TB, human immunodeficiency virus positivity, Russian ethnicity, non-permanent living situation, alcohol abuse and detention. XDR-TB cases had the highest risk of recent transmission. The majority of transmission cases involved individuals aged 30-39 years.
  
  
  CONCLUSIONS
  Recent TB transmission in Estonia is high and is particularly associated with MDR- and XDR-TB and the Beijing lineage.
authors.affiliation: United Laboratories, Tartu University Hospital, Tartu, Estonia ; Department of Pulmonary Medicine, University of Tartu, Tartu, Estonia.
authors.forename: K
authors.initials: K
authors.lastname: Toit
authors.affiliation: Department of Pulmonary Medicine, University of Tartu, Tartu, Estonia ; Lung Clinic, Tartu University Hospital, Tartu, Estonia.
authors.forename: A
authors.initials: A
authors.lastname: Altraja
authors.affiliation: Tuberculosis and M/XDR-TB Programme, Division of Communicable Diseases, Health Security & Environment, World Health Organization Regional Office for Europe, Copenhagen, Denmark.
authors.forename: C D
authors.initials: CD
authors.lastname: Acosta
authors.affiliation: National Institute for Health Development, Tallinn, Estonia.
authors.forename: P
authors.initials: P
authors.lastname: Viiklepp
authors.affiliation: Tuberculosis and M/XDR-TB Programme, Division of Communicable Diseases, Health Security & Environment, World Health Organization Regional Office for Europe, Copenhagen, Denmark ; Centre for Infectious Diseases Control, National Institute of Public Health and the Environment, Bilthoven, The Netherlands.
authors.forename: K
authors.initials: K
authors.lastname: Kremer
authors.affiliation: United Laboratories, Tartu University Hospital, Tartu, Estonia.
authors.forename: T
authors.initials: T
authors.lastname: Kummik
authors.affiliation: Lung Clinic, Tartu University Hospital, Tartu, Estonia.
authors.forename: M
authors.initials: M
authors.lastname: Danilovitš
authors.affiliation: Medical Department, Brussels Operational Center, Médecins Sans Frontières MSF-Luxembourg, Luxembourg.
authors.forename: R
authors.initials: R
authors.lastname: Van den Bergh
authors.affiliation: International Union Against Tuberculosis and Lung Disease, Paris, France ; London School of Hygiene & Tropical Medicine, London, UK.
authors.forename: A D
authors.initials: AD
authors.lastname: Harries
authors.affiliation: Institut National de la Santé et de la Recherche Médicale 1019, Lille, France ; Unités Mixtes de Recherche 8204, Centre national de la Recherche scientifique, Lille, France ; Center for Infection and Immunity of Lille, Institut Pasteur de Lille, Lille, France ; University Nord de France, Lille, France.
authors.forename: P
authors.initials: P
authors.lastname: Supply
keywords: Beijing lineage; MDR-TB; SORT IT; clustering; operational research