title: Molecular epidemiology of foodborne hepatitis a outbreaks in the United States, 2003.
abstract: BACKGROUND
  Molecular epidemiologic investigations can link geographically separate foodborne hepatitis A outbreaks but have not been used while field investigations are in progress. In 2003, outbreaks of foodborne hepatitis A were reported in multiple states.
  
  
  METHODS
  Case-control studies were conducted in 3 states. Hepatitis A virus was sequenced from serologic specimens from individuals associated with outbreaks and from individuals concurrently ill with hepatitis A in non-outbreak settings in the United States and Mexico.
  
  
  RESULTS
  Case-control studies in Tennessee (TN), North Carolina (NC), and Georgia (GA) found green onions to be associated with illness among restaurant patrons (TN: odds ratio [OR], 65.5 [95% confidence interval {CI}, 8.9-482.5; NC: OR, 2.4 [95% CI, 0.3-21.9]; GA: OR, 20.9 [95% CI, 3.9-110.3]). Viral sequences from TN case patients differed by 2 nt, compared with those from case patients in NC and GA. A third sequence, differing from the TN and GA/NC sequences by 1 nt, was identified among case patients in a subsequent outbreak in Pennsylvania. Each outbreak sequence was identical to > or =1 sequence isolated from northern Mexican resident(s) with hepatitis A. The sources of green onions served in restaurants in TN and GA were 3 farms in northern Mexico.
  
  
  CONCLUSIONS
  Ongoing viral strain surveillance facilitated the rapid implementation of control measures. Incorporation of molecular epidemiologic methods into routine hepatitis A surveillance would improve the detection of hepatitis A outbreaks and increase our understanding of hepatitis A epidemiology in the United States.
authors.affiliation: Epidemic Intelligence Service, Epidemiology Program Office and Division of Viral Hepatitis, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Amon
authors.forename: Rose
authors.initials: R
authors.lastname: Devasia
authors.forename: Guoliang
authors.initials: G
authors.lastname: Xia
authors.forename: Omana V
authors.initials: OV
authors.lastname: Nainan
authors.forename: Stephanie
authors.initials: S
authors.lastname: Hall
authors.forename: Brian
authors.initials: B
authors.lastname: Lawson
authors.forename: Julie S
authors.initials: JS
authors.lastname: Wolthuis
authors.forename: Pia D M
authors.initials: PD
authors.lastname: Macdonald
authors.forename: Colin W
authors.initials: CW
authors.lastname: Shepard
authors.forename: Ian T
authors.initials: IT
authors.lastname: Williams
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Armstrong
authors.forename: Julie A
authors.initials: JA
authors.lastname: Gabel
authors.forename: Paul
authors.initials: P
authors.lastname: Erwin
authors.forename: Lorinda
authors.initials: L
authors.lastname: Sheeler
authors.forename: Wendi
authors.initials: W
authors.lastname: Kuhnert
authors.forename: Priti
authors.initials: P
authors.lastname: Patel
authors.forename: Gilberto
authors.initials: G
authors.lastname: Vaughan
authors.forename: Andre
authors.initials: A
authors.lastname: Weltman
authors.forename: Allen S
authors.initials: AS
authors.lastname: Craig
authors.forename: Beth P
authors.initials: BP
authors.lastname: Bell
authors.forename: Anthony
authors.initials: A
authors.lastname: Fiore
mesh_terms: D016022:Case-Control Studies; D004196:Disease Outbreaks / Q000706:statistics & numerical data; D005511:Food Handling; D005516:Food Microbiology; D005517:Foodborne Diseases / Q000453:epidemiology / Q000821:virology; D006506:Hepatitis A / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality; D030041:Hepatitis A virus / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D017720:Molecular Epidemiology; D014481:United States / Q000453:epidemiology