|Cray, Jr, William|
|Moon, Harley - IOWA STATE UNIV., AMES|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 4, 1996
Publication Date: N/A
Technical Abstract: Escherichia coli O157:H7 has been isolated from approximately 1-2% of U.S. cattle during farm and feedlot surveys. Cattle are intermittently infected and the organism appears to be confined to the G.I. tract in healthy animals. Some herds maintain a high or low prevalence over time, suggesting that management practices may affect intra-herd prevalence. In experimentally inoculated cattle of the same age, there is wide variation in magnitude and duration of fecal shedding of E. coli O157:H7. Shedding of E. coli O157:H7 is usually longer in calves than adults and may persist for several months. Serum antibody titers to O157 LPS or Shiga-like toxin 1 neutralizing antibody titers do not appear to be associated with duration of shedding of the organism, nor do they protect calves from reinfection by the same strain of E. coli O157:H7. Susceptibility to infection by the organism increases when food is withheld from cattle, which may occur when animals are marketed. Because shedding of E. coli O157:H7 varies greatly among animals of similar age, unknown ecological factors may modulate growth of the organism in vivo. When these factors are identified, they may be exploited to help limit E. coli O157:H7 in cattle.