title: Herd-level risk factors associated with the presence of Phage type 21/28 E. coli O157 on Scottish cattle farms.
abstract: BACKGROUND
  E. coli O157 is a bacterial pathogen that is shed by cattle and can cause severe disease in humans. Phage type (PT) 21/28 is a subtype of E. coli O157 that is found across Scotland and is associated with particularly severe human morbidity.
  
  
  METHODS
  A cross-sectional survey of Scottish cattle farms was conducted in the period Feb 2002-Feb 2004 to determine the prevalence of E. coli O157 in cattle herds. Data from 88 farms on which E. coli O157 was present were analysed using generalised linear mixed models to identify risk factors for the presence of PT 21/28 specifically.
  
  
  RESULTS
  The analysis identified private water supply, and northerly farm location as risk factors for PT 21/28 presence. There was a significant association between the presence of PT 21/28 and an increased number of E. coli O157 positive pat samples from a farm, and PT 21/28 was significantly associated with larger E. coli O157 counts than non-PT 21/28 E. coli O157.
  
  
  CONCLUSIONS
  PT 21/28 has significant risk factors that distinguish it from other phage types of E. coli O157. This finding has implications for the control of E. coli O157 as a whole and suggests that control could be tailored to target the locally dominant PT.
authors.affiliation: Centre for Infectious Diseases, University of Edinburgh, Easter Bush, Roslin, Midlothian, EH25 9RG, UK. J.E.B.Halliday@sms.ed.ac.uk
authors.forename: Jo E B
authors.initials: JE
authors.lastname: Halliday
authors.forename: Margo E
authors.initials: ME
authors.lastname: Chase-Topping
authors.forename: Michael C
authors.initials: MC
authors.lastname: Pearce
authors.forename: Iain J
authors.initials: IJ
authors.lastname: McKendrick
authors.forename: Lesley
authors.initials: L
authors.lastname: Allison
authors.forename: Dave
authors.initials: D
authors.lastname: Fenlon
authors.forename: Chris
authors.initials: C
authors.lastname: Low
authors.forename: Dominic J
authors.initials: DJ
authors.lastname: Mellor
authors.forename: George J
authors.initials: GJ
authors.lastname: Gunn
authors.forename: Mark E J
authors.initials: ME
authors.lastname: Woolhouse
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D001434:Bacteriophage Typing; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology; D003090:Coliphages / Q000302:isolation & purification*; D015169:Colony Count, Microbial; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000145:classification / Q000302:isolation & purification / Q000821:virology; D005243:Feces / Q000382:microbiology; D012307:Risk Factors; D012606:Scotland / Q000453:epidemiology; D022622:Shiga Toxin 1 / Q000235:genetics; D014881:Water Supply
chemical_list: D022622:Shiga Toxin 1