Modeling the Transport and Survival of E. Coli O157:H7 in Agricultural Settings.

E.coli O157:H7 is an important pathogen found in animal wastes that has been linked to food- and water-borne disease outbreaks in agricultural settings.  Much research has been directed to quantify the transport or the survival of E.coli O157:H7 in soils in order to assess and mitigate risks.  However, little research has examined the simultaneous transport and survival of E.coli O157:H7 because of the complexity of these individual processes, and differences in analytic methods, experimental procedures and time scales, and modeling approaches.  Risks of environmental dissemination of E.coli O157:H7 in agricultural settings are intimately linked to both transport and survival processes that are functions of temperature, solution chemistry, cell concentration, and water flow conditions.  A sophisticated mathematical model has been developed to simulate E.coli O157:H7 fate.  This model includes provisions for Weibull and logistic survival as a function of temperature, and advective and dispersive transport in the bulk aqueous phase, rolling on the solid phase, immobilization, aggregation, and release from the solid surface with solution ionic strength, water velocity, and input concentration.  This model was used to simulate the coupled survival and transport of E.coli O157:H7 under a variety of environmentally relevant scenarios.  Transport and survival parameters were derived from published experimental studies.