SURVIVAL OF E. COLI 0157:H7 IN AERATED DAIRY MANURE LAGOONS.

Authors: Stanker, Larry; Ravva, Subbarao

Submitted to: United States Japan Joint Protein Research Panels
Publication Type: Proceedings
Publication Acceptance Date: 12/10/2002
Publication Date: 12/10/2002
Citation: Stanker, L.H. and Ravva, S.V., 2002. Survival of E. coli 0157:H7 in aerated dairy manure lagoons. In Cherry, J.P. and Pavlath, A.E. (eds.) Proceedings of the 31st United States-Japan Cooperative Program in Natural Resources (UJNR) Protein Resources Panel, p. M1-6, December 1-6, 2002, Monterey, CA.

Interpretive Summary: N/A

Technical Abstract: Foodborne illnesses caused by pathogenic bacteria are increasingly being linked to contaminated fruits and vegetables. Animal manure is a potential pathogen reservoir, and the close proximity of dairies and croplands in California cannot be ignored. We are evaluating the cycle of transfer of pathogens from animals to agricultural crops and factors that stimulate pathogen re-growth and transmission to dairy animals. Aeration of manure lagoons is gaining importance in recent years for reduction of odors, retention of nutrients and controlling pathogens. The survival of human pathogenic E. coli O157:H7 marked with rifampin resistance was monitored in aerated and non-aerated manure water from a California dairy farm with active manure management practices that include separation of manure solids followed by aeration in lagoons. Laboratory scale manure water microcosms aerated with miniaturized circulating aerators were used to monitor the survival and proliferation of pathogens. The populations of E .coli O157:H7 declined rapidly from 105 cells/mL to undetectable levels in less than 1 week. Strain variations were noted for the extent of survival in manure lagoon microcosms. A strain of O157:H7 recently isolated from a dairy survived longer than did isolates obtained from the Albany culture collection. The possibility of pathogen re-growth (to levels capable of causing outbreaks) as a result of continuous fecal shedding of pathogens in manure water lagoons was evaluated in laboratory microcosms. The levels of E. coli O157:H7 were monitored in manure lagoon waters that were repeatedly inoculated (the bacterial concentration was adjusted to 105 E. coli O157:H7 cells/ml) at weekly intervals for one. The pathogen failed to establish itself during the five weekly re-inoculation periods and the numbers repeatedly declined to undetectable levels between re-inoculation intervals. The practical implication of the absence of re-growth on dairy farms of low levels of pathogen during active fecal shedding of pathogenic E. coli needs further evaluation. The studies on pathogen survival in manure lagoons are critical in determining the potential for pathogen transmission through crops grown on-site following fertilization and irrigation with manure water.