Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2006
Publication Date: 12/20/2006
Citation: Edrington, T.S., Callaway, T.R., Ives, S.E., Engler, M.J., Looper, M.L., Anderson, R.C., Nisbet, D.J. 2006. Seasonal shedding of Escherichia coli O157:H7 in ruminants: A new hypothesis. Foodborne Pathogens and Disease. 3(4):413-421.
Interpretive Summary: Cattle and sheep are naturally infected with E. coli O157:H7, a bacteria that causes food sickness in humans. This bacteria is more common in cattle in the summer months than in the winter but nobody knows the reason for this seasonality. Temperature has been suggested as the cause, however, E. coli is quite common in Canada and the Northern United States, as well as the Southern United States, suggesting temperature is not the causative factor. Analysis of research reporting the prevalence of E. coli O157:H7 in cattle shows that a positive correlation exists between day-length and E. coli prevalence and that temperature is weakly correlated. Understanding the biology of E. coli O157:H7 will enable the design of effective strategies to control this bacteria.
Technical Abstract: Seasonal shedding of E. coli O157:H7 is well documented, however viable explanations for this phenomenon are lacking. Nine references reporting E. coli O157:H7 prevalence in cattle were selected for similarity of sampling technique, culture methodology, cattle type, and ability to determine approximate sampling month and location, representing three regions in North America (southern Canada, midwest U.S., and the southern U.S./Mexico). Correlation and regression analysis revealed a positive correlation existed between day-length (r = 0.67; R**2 = 0.45; P = 0.0009) and to a lesser extent, ambient temperature (r = 0.43; R**2= 0.19; P = 0.05), and E. coli O157:H7 prevalence.