title: Twenty years and counting: epidemiology of an outbreak of isoniazid-resistant tuberculosis in England and Wales, 1995 to 2014.
abstract: An outbreak of isoniazid-resistant tuberculosis first identified in London has now been ongoing for 20 years, making it the largest drug-resistant outbreak of tuberculosis documented to date worldwide. We identified culture-confirmed cases with indistinguishable molecular strain types and extracted demographic, clinical, microbiological and social risk factor data from surveillance systems. We summarised changes over time and used kernel-density estimation and k-function analysis to assess geographic clustering. From 1995 to 2014, 508 cases were reported, with a declining trend in recent years. Overall, 70% were male (n = 360), 60% born in the United Kingdom (n = 306), 39% white (n = 199), and 26% black Caribbean (n = 134). Median age increased from 25 years in the first 5 years to 42 in the last 5. Approximately two thirds of cases reported social risk factors: 45% drug use (n = 227), 37% prison link (n = 189), 25% homelessness (n = 125) and 13% alcohol dependence (n = 64). Treatment was completed at 12 months by 52% of cases (n = 206), and was significantly lower for those with social risk factors (p < 0.05), but increased over time for all patients (p < 0.05). The outbreak remained focused in north London throughout. Control of this outbreak requires continued efforts to prevent and treat further active cases through targeted screening and enhanced case management.
authors.affiliation: Farr Institute of Health Informatics Research, Department of Infectious Disease Informatics, University College London, London, United Kingdom.|These authors contributed equally to this work.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Smith
authors.affiliation: These authors contributed equally to this work.|Field Epidemiology Service, Liverpool, United Kingdom.|Field Epidemiology Training Programme, Public Health England, London, United Kingdom.|European Programme for Intervention Epidemiology Training, European Centre for Disease Prevention and Control, Stockholm, Sweden.
authors.forename: Suzan C M
authors.initials: SC
authors.lastname: Trienekens
authors.affiliation: Field Epidemiology Service - South East and London, Public Health England, London, United Kingdom.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Anderson
authors.affiliation: Public Health England TB Section, Centre for Infectious Disease Surveillance and Control, Colindale, London, United Kingdom.|Research Department Infection and Population Health, Centre for Infectious Disease Epidemiology, University College London, London, United Kingdom.
authors.forename: Maeve K
authors.initials: MK
authors.lastname: Lalor
authors.affiliation: Public Health England National Mycobacterium Reference Laboratory, Whitechapel, London, United Kingdom.
authors.forename: Tim
authors.initials: T
authors.lastname: Brown
authors.affiliation: Farr Institute of Health Informatics Research, Department of Infectious Disease Informatics, University College London, London, United Kingdom.|Find and Treat, University College Hospitals NHS Foundation Trust, London, United Kingdom.
authors.forename: Alistair
authors.initials: A
authors.lastname: Story
authors.affiliation: Centre for Advanced Spatial Analysis, University College London, London, United Kingdom.
authors.forename: Hannah
authors.initials: H
authors.lastname: Fry
authors.affiliation: Farr Institute of Health Informatics Research, Department of Infectious Disease Informatics, University College London, London, United Kingdom.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Hayward
authors.affiliation: Field Epidemiology Service - South East and London, Public Health England, London, United Kingdom.|Research Department Infection and Population Health, Centre for Infectious Disease Epidemiology, University College London, London, United Kingdom.
authors.forename: Helen
authors.initials: H
authors.lastname: Maguire
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000995:Antitubercular Agents / Q000627:therapeutic use*; D004196:Disease Outbreaks; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D007538:Isoniazid / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D012150:Polymorphism, Restriction Fragment Length; D012307:Risk Factors; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy* / Q000453:epidemiology*; D014852:Wales / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents; D007538:Isoniazid
keywords: antimicrobial resistance; geographic information system – GIS; outbreaks; social risk factors; tuberculosis; typing