title: An Outbreak of Cryptosporidium parvum across England & Scotland Associated with Consumption of Fresh Pre-Cut Salad Leaves, May 2012.
abstract: BACKGROUND
  We report a widespread foodborne outbreak of Cryptosporidium parvum in England and Scotland in May 2012. Cases were more common in female adults, and had no history of foreign travel. Over 300 excess cases were identified during the period of the outbreak. Speciation and microbiological typing revealed the outbreak strain to be C. parvum gp60 subtype IIaA15G2R1.
  
  
  METHODS
  Hypothesis generation questionnaires were administered and an unmatched case control study was undertaken to test the hypotheses raised. Cases and controls were interviewed by telephone. Controls were selected using sequential digit dialling. Information was gathered on demographics, foods consumed and retailers where foods were purchased.
  
  
  RESULTS
  Seventy-four laboratory confirmed cases and 74 controls were included in analyses. Infection was found to be strongly associated with the consumption of pre-cut mixed salad leaves sold by a single retailer. This is the largest documented outbreak of cryptosporidiosis attributed to a food vehicle.
authors.affiliation: Public Health England, Field Epidemiology Services, London, England, United Kingdom; Field Epidemiology Training Programme, Public Health England, London, England, United Kingdom.
authors.forename: Caoimhe
authors.initials: C
authors.lastname: McKerr
authors.affiliation: Department of Gastrointestinal, Emerging & Zoonotic Infections, Public Health England, London, England, United Kingdom.
authors.forename: Goutam K
authors.initials: GK
authors.lastname: Adak
authors.affiliation: Department of Gastrointestinal, Emerging & Zoonotic Infections, Public Health England, London, England, United Kingdom; Norwich Medical School, University of East Anglia, Norwich, England, United Kingdom; Faculty of Medicine, University of Thessaly, Larissa, Greece; European Centre for Environment and Human Health, University of Exeter, Exeter, England, United Kingdom.
authors.forename: Gordon
authors.initials: G
authors.lastname: Nichols
authors.affiliation: Public Health England, Field Epidemiology Services, London, England, United Kingdom.
authors.forename: Russell
authors.initials: R
authors.lastname: Gorton
authors.affiliation: Cryptosporidium Reference Unit, Public Health Wales, Swansea, Wales, United Kingdom.
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Chalmers
authors.affiliation: Statistics, Modelling and Economics Department, Public Health England, London, England, United Kingdom.
authors.forename: George
authors.initials: G
authors.lastname: Kafatos
authors.affiliation: Public Health England, London, England, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Cosford
authors.affiliation: Statistics, Modelling and Economics Department, Public Health England, London, England, United Kingdom.
authors.forename: Andre
authors.initials: A
authors.lastname: Charlett
authors.affiliation: Public Health England, Field Epidemiology Services, London, England, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Reacher
authors.affiliation: Health Protection Scotland, Glasgow, Scotland, United Kingdom.
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Pollock
authors.affiliation: Health Protection Scotland, Glasgow, Scotland, United Kingdom.
authors.forename: Claire L
authors.initials: CL
authors.lastname: Alexander
authors.affiliation: Public Health England Centre, Yorkshire & Humber, England, United Kingdom.
authors.forename: Stephen
authors.initials: S
authors.lastname: Morton
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003457:Cryptosporidiosis / Q000453:epidemiology* / Q000469:parasitology; D016785:Cryptosporidium parvum / Q000235:genetics / Q000472:pathogenicity*; D004196:Disease Outbreaks; D004739:England / Q000453:epidemiology; D005260:Female; D005517:Foodborne Diseases / Q000453:epidemiology*; D006801:Humans; D018545:Lactuca / Q000469:parasitology; D008297:Male; D008875:Middle Aged; D018515:Plant Leaves / Q000469:parasitology; D012606:Scotland / Q000453:epidemiology; D055815:Young Adult