title: Methamphetamine injecting is associated with phylogenetic clustering of hepatitis C virus infection among street-involved youth in Vancouver, Canada.
abstract: BACKGROUND
  Among prospective cohorts of people who inject drugs (PWID), phylogenetic clustering of HCV infection has been observed. However, the majority of studies have included older PWID, representing distant transmission events. The aim of this study was to investigate phylogenetic clustering of HCV infection among a cohort of street-involved youth.
  
  
  METHODS
  Data were derived from a prospective cohort of street-involved youth aged 14-26 recruited between 2005 and 2012 in Vancouver, Canada (At Risk Youth Study, ARYS). HCV RNA testing and sequencing (Core-E2) were performed on HCV positive participants. Phylogenetic trees were inferred using maximum likelihood methods and clusters were identified using ClusterPicker (Core-E2 without HVR1, 90% bootstrap threshold, 0.05 genetic distance threshold).
  
  
  RESULTS
  Among 945 individuals enrolled in ARYS, 16% (n=149, 100% recent injectors) were HCV antibody positive at baseline interview (n=86) or seroconverted during follow-up (n=63). Among HCV antibody positive participants with available samples (n=131), 75% (n=98) had detectable HCV RNA and 66% (n=65, mean age 23, 58% with recent methamphetamine injection, 31% female, 3% HIV+) had available Core-E2 sequences. Of those with Core-E2 sequence, 14% (n=9) were in a cluster (one cluster of three) or pair (two pairs), with all reporting recent methamphetamine injection. Recent methamphetamine injection was associated with membership in a cluster or pair (P=0.009).
  
  
  CONCLUSIONS
  In this study of street-involved youth with HCV infection and recent injecting, 14% demonstrated phylogenetic clustering. Phylogenetic clustering was associated with recent methamphetamine injection, suggesting that methamphetamine drug injection may play an important role in networks of HCV transmission.
authors.affiliation: Viral Hepatitis Clinical Research Program, The Kirby Institute, UNSW Australia, Sydney, NSW, Australia. Electronic address: ecunningham@kirby.unsw.edu.au.
authors.forename: Evan B
authors.initials: EB
authors.lastname: Cunningham
authors.affiliation: Viral Hepatitis Clinical Research Program, The Kirby Institute, UNSW Australia, Sydney, NSW, Australia.
authors.forename: Brendan
authors.initials: B
authors.lastname: Jacka
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; School of Public Policy, Simon Fraser University, Vancouver, BC, Canada.
authors.forename: Kora
authors.initials: K
authors.lastname: DeBeck
authors.affiliation: Viral Hepatitis Clinical Research Program, The Kirby Institute, UNSW Australia, Sydney, NSW, Australia.
authors.forename: Tanya L
authors.initials: TL
authors.lastname: Applegate
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada.
authors.forename: P Richard
authors.initials: PR
authors.lastname: Harrigan
authors.affiliation: BC Centre for Disease Control, Vancouver, BC, Canada.
authors.forename: Mel
authors.initials: M
authors.lastname: Krajden
authors.affiliation: Department of Epidemiology, Brown University School of Public Health, Providence, RI, United States.
authors.forename: Brandon D L
authors.initials: BD
authors.lastname: Marshall
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Division of AIDS, Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Julio
authors.initials: J
authors.lastname: Montaner
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Division of AIDS, Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Viviane Dias
authors.initials: VD
authors.lastname: Lima
authors.affiliation: BC Centre for Disease Control, Vancouver, BC, Canada.
authors.forename: Andrea D
authors.initials: AD
authors.lastname: Olmstead
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Division of AIDS, Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: M-J
authors.initials: MJ
authors.lastname: Milloy
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Division of AIDS, Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Evan
authors.initials: E
authors.lastname: Wood
authors.affiliation: Viral Hepatitis Clinical Research Program, The Kirby Institute, UNSW Australia, Sydney, NSW, Australia.
authors.forename: Jason
authors.initials: J
authors.lastname: Grebely
mesh_terms: D000293:Adolescent; D000328:Adult; D001955:British Columbia / Q000453:epidemiology; D005260:Female; D006526:Hepatitis C / Q000453:epidemiology* / Q000635:transmission / Q000821:virology*; D018453:Homeless Youth / Q000706:statistics & numerical data*; D006801:Humans; D007267:Injections; D008297:Male; D008694:Methamphetamine / Q000008:administration & dosage*; D010802:Phylogeny; D011446:Prospective Studies; D012651:Self Medication / Q000009:adverse effects; D015819:Substance Abuse, Intravenous / Q000150:complications / Q000453:epidemiology* / Q000821:virology*
chemical_list: D008694:Methamphetamine
keywords: Clustering; Injection drug use; Methamphetamine; Phylogenetic clustering; Phylogenetics; Street-involved youth