title: Risk factors for infection with verocytotoxigenic Escherichia coli in cattle on Ontario dairy farms.
abstract: Risk factors for prevalent infection with verocytotoxigenic Escherichia coli (VTEC) were studied in a random sample of 886 cows and 592 calves under 3 months of age on 80 randomly selected dairy farms in southern Ontario. Fecal-culture supernatants from each animal were screened for verocytotoxicity using a Vero cell assay (VCA) and for verocytotoxin (VT) genes by a polymerase chain reaction (PCR) procedure. Up to 20 F. colt isolates from positive samples were tested for VT production using VCA and PCR. VTEC isolates were serotyped. Farm managers were interviewed using a standardized questionnaire to obtain information on farm- and individual animal-level management practices and characteristics. There was a significant (P < 0.001) positive association between age of calves and their VTEC infection status, and calves were significantly more likely to be infected than cows. The proportion of calves infected on the farm was positively associated with both the use of regular pails for feeding calves (as opposed to nipple bottles or nipple pails) and bringing new animals into the herd in the previous year.
authors.affiliation: Ontario Veterinary College, University of Guelph, Canada. JWILSON@OVCNET.UOGUELPH.CA
authors.forename: J B
authors.initials: JB
authors.lastname: Wilson
authors.forename: S A
authors.initials: SA
authors.lastname: Renwick
authors.forename: R C
authors.initials: RC
authors.lastname: Clarke
authors.forename: K
authors.initials: K
authors.lastname: Rahn
authors.forename: D
authors.initials: D
authors.lastname: Alves
authors.forename: R P
authors.initials: RP
authors.lastname: Johnson
authors.forename: A G
authors.initials: AG
authors.lastname: Ellis
authors.forename: S A
authors.initials: SA
authors.lastname: McEwen
authors.forename: M A
authors.initials: MA
authors.lastname: Karmali
authors.forename: H
authors.initials: H
authors.lastname: Lior
authors.forename: J
authors.initials: J
authors.lastname: Spika
mesh_terms: D000367:Age Factors; D000822:Animal Husbandry / Q000592:standards; D000818:Animals; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000633:toxicity; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology*; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D003627:Data Interpretation, Statistical; D019992:Databases as Topic; D004768:Enterotoxins / Q000096:biosynthesis / Q000633:toxicity; D004926:Escherichia coli / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000175:diagnosis / Q000453:epidemiology / Q000662:veterinary*; D005243:Feces / Q000382:microbiology; D005260:Female; D015999:Multivariate Analysis; D009864:Ontario / Q000453:epidemiology; D016133:Polymerase Chain Reaction; D022622:Shiga Toxin 1; D012984:Software; D014709:Vero Cells / Q000187:drug effects
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins; D022622:Shiga Toxin 1