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Title: PREVALENCE OF ESCHERICHIA COLI O157:H7 IN RANGE BEEF CALVES AT WEANING

Author
item LAEGREID, WILLIAM
item ELDER, ROBERT
item KEEN, JAMES

Submitted to: Epidemiology and Infection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: E. coli O157:H7 is an important cause of foodborne disease in the U.S. This bacteria is present in beef cattle which serve as a reservoir for human infection. To control E. coli O157:H7 in cattle we must understand how many and at what points in the production cycle cattle become infected. We asked the following question: are most calves becoming infected before weaning or after weaning in the feedlot? Range beef calves from 15 herds in 5 states were sampled at weaning. Thirteen of fifteen herds were positive, with an average of 7.4% of calves shedding E. coli O157:H7 in their feces. More than 83% of all calves had antibodies to O157, indicating previous exposure to E. coli O157:H7. These results show that most calves on range have been exposed or infected with E. coli O157:H7 prior to weaning. Thus, efforts to control E. coli O157:H7 should include interventions early in the production cycle.

Technical 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. Fecal culture for E. coli O157:H7 was performed and anti-O157 serum antibody titers were determined by blocking ELISA. Thirteen of the fifteen herds (87%) were found to have at least one positive isolation of E. coli O157:H7 in fecal samples. All herds had high prevalence of anti-O157 antibodies, with seroprevalence ranging from 63 to 100%. 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.