Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: November 28, 2005
Publication Date: February 4, 2006
Citation: Edrington, T.S., Callaway, T.R., Genovese, K.J., Anderson, R.C., Nisbet, D.J. 2006. Research examining seasonal shedding of E. coli O157:H7 [abstract]. American Society of Animal Science. Paper No. 90. Technical Abstract: Recent estimates suggest that E. coli O157:H7 may have cost the beef industry as much as $2.7 billion in the past 10 years and does not include the nearly $1 billion spent annually on the approximately 73,000 human illnesses that occur in the United States as a result of this pathogen. Cattle are natural reservoirs for this bacterium and typically appear non-symptomatic while shedding this pathogen into the environment. Seasonal variation has been associated with E. coli O157:H7 with peak prevalence occurring during the summer and early fall and very low levels of infection reported in the winter months. Interestingly, although seasonal shedding of E. coli O157:H7 is well documented and generally accepted, a plausible explanation has not been produced. Ambient temperature is most often suggested as responsible for the seasonality of E. coli O157:H7, however, recent research at our laboratory has demonstrated day-length and physiological responses within the host animal as a result of changing day-length, may play a greater role. The pineal and thyroid are two glands known to respond to seasonal changes in day-length. Results of research examining exogenous melatonin as well as thyroid inhibition and tri-iodo-thyronine (T3) administration, supports our hypothesis that hormonal response to changing day-length may be involved in seasonal shedding patterns of E. coli O157:H7 in beef cattle.