title: Prevalence of Escherichia coli O157:H7 in range beef calves at weaning.
abstract: This study was designed to determine the prevalence of Escherichia coli O157:H7 infection of beef calves at weaning, prior to arrival at the feedlot or mixing with cattle from other sources. Fifteen range cow-calf herds, which weaned calves in October and November, were sampled in Kansas, Missouri, Montana, Nebraska and South Dakota. Faecal culture for E. coli O157:H7 was performed and anti-O157 serum antibody titres were determined by blocking ELISA. Thirteen of the 15 herds (87%) were found to have at least one positive isolation of E. coli O157:H7 in faecal samples. Within positive herds, prevalence ranged from 1.7-20.0%, with an average of 7.4+/-6.2% S.D. of individual animals shedding E. coli O157:H7 in faeces. All herds had high prevalence of anti-O157 antibodies, ranging 63-100% of individuals within herds seropositive. This study indicates that E. coli O157:H7 infection before weaning, prior to entry into feedlots, is widespread. Furthermore, serologic evidence suggests that most calves (83%) and all herds (100%) have been exposed to E. coli O157.
authors.affiliation: Animal Health Research Unit, US Meat Animal Research Center, USDA, ARS, Clay Center, Nebraska 68933, USA.
authors.forename: W W
authors.initials: WW
authors.lastname: Laegreid
authors.forename: R O
authors.initials: RO
authors.lastname: Elder
authors.forename: J E
authors.initials: JE
authors.lastname: Keen
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000382:microbiology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D004797:Enzyme-Linked Immunosorbent Assay; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D007615:Kansas / Q000453:epidemiology; D008923:Missouri / Q000453:epidemiology; D009009:Montana / Q000453:epidemiology; D009329:Nebraska / Q000453:epidemiology; D015995:Prevalence; D013023:South Dakota / Q000453:epidemiology