title: High Proportion of Asymptomatic Infections in an Outbreak of Hepatitis E Associated With a Spit-Roasted Piglet, France, 2013.
abstract: BACKGROUND
  On 11 December 2013, 3 clustered cases of hepatitis E were reported on a French coastal island. Individuals had taken part in a wedding meal that included a spit-roasted piglet. The piglet had been stuffed with a raw stuffing partly made from the liver. Investigations were carried out to identify the vehicle of contamination and evaluate the dispersion of the hepatitis E virus (HEV) in the environment.
  
  
  METHODS
  A questionnaire was administered to 98 wedding participants who were asked to give a blood sample. Cases were identified by reverse transcription-polymerase chain reaction and serological tests. A retrospective cohort study was conducted among 38 blood-sampled participants after the exclusion of 14 participants with evidence of past HEV infection. Relative risks (RR) and 95% confidence intervals were calculated based on food consumed at the wedding meal using univariate and multivariable Poisson regressions. Phylogenetic analyses were performed to compare the clinical HEV strains. Strains were detected in the liquid manure sampled at the farm where the piglet was born and in the untreated island wastewater.
  
  
  RESULTS
  Seventeen cases were identified, 70.6% were asymptomatic. Acute HEV infection was independently associated with piglet stuffing consumption (RR = 1.69 [1.04-2.73], P = .03). Of clinical strains from the index cases, veterinary and environmental HEV strains were identical.
  
  
  CONCLUSIONS
  Our investigation attributed this large HEV outbreak to the consumption of an undercooked pig liver-based stuffing. After infection, the cases became a temporary reservoir for HEV, which was detected in the island's untreated wastewater.
authors.affiliation: Regional Epidemiology Unit for the Brittany region, Institut de veille sanitaire, Rennes.
authors.forename: Yvonnick
authors.initials: Y
authors.lastname: Guillois
authors.affiliation: National Reference Center for Hepatitis E virus, Centre hospitalier universitaire, Toulouse.
authors.forename: Florence
authors.initials: F
authors.lastname: Abravanel
authors.affiliation: Laboratoire de Microbiologie, LSEM-SG2M, Ifremer, Nantes.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Miura
authors.affiliation: UMR 1161 Virology, Animal Health Laboratory, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail, Maisons-Alfort.
authors.forename: Nicole
authors.initials: N
authors.lastname: Pavio
authors.affiliation: Department of Infectious diseases, Institut de veille sanitaire, Saint-Maurice.
authors.forename: Véronique
authors.initials: V
authors.lastname: Vaillant
authors.affiliation: National Reference Center for Hepatitis E virus, Centre hospitalier universitaire, Toulouse.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Lhomme
authors.affiliation: Laboratoire de Microbiologie, LSEM-SG2M, Ifremer, Nantes.
authors.forename: Françoise S
authors.initials: FS
authors.lastname: Le Guyader
authors.affiliation: Swine Epidemiology and Welfare unit, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail, Ploufragan/Plouzané laboratory, Ploufragan, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Rose
authors.affiliation: Laboratoire de Microbiologie, LSEM-SG2M, Ifremer, Nantes.
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Le Saux
authors.affiliation: Regional Epidemiology Unit for the Brittany region, Institut de veille sanitaire, Rennes.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: King
authors.affiliation: National Reference Center for Hepatitis E virus, Centre hospitalier universitaire, Toulouse.
authors.forename: Jacques
authors.initials: J
authors.lastname: Izopet
authors.affiliation: Department of Infectious diseases, Institut de veille sanitaire, Saint-Maurice.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Couturier
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D058345:Asymptomatic Infections / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D004783:Environmental Microbiology; D005260:Female; D005517:Foodborne Diseases / Q000453:epidemiology*; D005602:France / Q000453:epidemiology; D016751:Hepatitis E / Q000453:epidemiology*; D016752:Hepatitis E virus / Q000145:classification / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012698:Serologic Tests; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: asymptomatic infection; hepatitis E virus; outbreak; pork liver; wastewater