title: Environmental and food safety aspects of Escherichia coli O157:H7 infections in cattle.
abstract: The presence of E. coli O157:H7 in cattle illustrates the complex, interrelated nature of the environment, livestock production practices, food safety, and the science of microbiology, particularly microbial ecology. Enterohemorrhagic E. coli, including E. coli O157:H7, can cause severe human diseases that can be debilitating and life threatening. Cattle are currently considered to be the definitive source for E. coli O157:H7 in the food supply, but this view may be simplistic and incomplete. E. coli O157:H7, appears widespread among U.S. cattle herds, while individual animal prevalence is low and transient. Most individual animals appear to be a transient reservoir for E. coli O157:H7 although the issue of carrier animals still remains unresolved. Epidemiological studies of the cattle production system have not clearly identified risk factors or management practices that affect E. coli O157:H7 prevalence in cattle feces. The problem of E. coli O157:H7 increases during the summer and fall months, but the environmental factors that contribute to this increase are poorly understood. Possible environmental factors that may influence E. coli O157:H7 shedding in cattle include livestock feed and waste handling practices as well as insects and microbial interactions in soil and water. Studies of E. coli O157:H7 ecology in cattle and the environment have been limited, but they suggest that a consideration of other independent, environmental sources of this microbe seems appropriate. The natural ecology of cholera may serve as a useful environmental model for pursuing additional environmental research on the occurrence and transmission of E. coli O157:H7 in nature.
authors.affiliation: Periparturient Diseases of Cattle Research Unit , USDA, Agricultural Research Service, Ames, IA 50010, USA. mrasmuss@nadc.ars.usda.gov
authors.forename: M A
authors.initials: MA
authors.lastname: Rasmussen
authors.forename: T A
authors.initials: TA
authors.lastname: Casey
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D004197:Disease Reservoirs; D017753:Ecosystem; D004783:Environmental Microbiology; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000472:pathogenicity*; D056890:Eukaryota / Q000382:microbiology; D005516:Food Microbiology; D006801:Humans; D012449:Safety; D014481:United States; D014774:Virulence