How does weather influence transmission of E. coli O157:H7 from animal operations to produce fields?

Animal operations adjacent to lands used for fresh produce production are a known risk for transmission of foodborne pathogens. Cattle represent one of the highest risk animals as they can be common reservoirs for numerous foodborne pathogens. Cattle operations have also been suspected in E. coli O157:H7 outbreaks associated with leafy greens in the past. We are still learning how the presence of animal operations contributes to pathogen contamination of adjacent lands. Weather has been suggested, but not proven, to influence the transmission of foodborne pathogens to the wider environment surrounding cattle operations. The goal of this study is to assess how specific weather conditions influence transmission of E. coli O157:H7 from animal operations to adjacent lands, and then develop a weather-based risk assessment model of E. coli O157:H7 transmission for field proximity to animal operations. This project will result in critical industry guidance about weather factors to account for environmental assessments during the pre-harvest stage of production for farms near cattle operations.

Animal operations adjacent to lands used for growing produce are a known risk for transmission of foodborne pathogens. Cattle represent one of the highest risk animals as they can be common reservoirs for numerous foodborne pathogens. Cattle operations have also been suspected in Escherichiacoli O157:H7 (E. coli O157:H7) leafy greens associated outbreaks in the past. Yet, we are still learning how the presence of animal operations contributes to contamination of adjacent lands. It has been hypothesized that weather may influence transmission and contamination of the wider environment surrounding cattle operations. The goal of this study is to assess specifically how weather conditions influence transmission of E. coli O157:H7 from animal operations to adjacent lands through the following objectives: 1) Identify normal and extreme weather events associated with an increased risk of E. coli O157:H7 transmission from a cattle feedlot to the surrounding environment, and 2) Development of risk assessment models based on field proximity to animal operation and E. coli O157:H7 transmission via weather. We hypothesize that overall weather conditions can be used to predict the distance and direction that E. coli O157:H7 will be transmitted from an animal operation to surrounding fields. We will accomplish these objectives by conducting environmental sampling of soil, air, water, surrogate plant samples, and cattle feces at the United States Meat Animal Research Center (USMARC) in Clay Center, Nebraska (NE). Sample collection will occur in eight different directions, at four different distances, and over ten two-week sampling periods from May to September for two years. We will use whole genome sequencing to genetically compare cattle and environmental strains of E. coli O157:H7 to confirm transmission from the animal operation. We will also collect data from on-site weather stations (temperature, precipitation, relative humidity, soil moisture, wind speed and direction) and conduct additional enhanced sampling before, and after extreme weather events (e.g. flooding, high wind, severe storms). These data will be merged with additional drought and weather indices, as well as wildlife/bird migration data to assess other potential sources of transmission. The final dataset will be used to develop risk assessment models for produce contamination based on presence of positive samples, persistence, and different distances to an animal feed operation. Machine learning and predictive analytics will be utilized to assess different weather patterns and factors associated with higher risk of transmitting E. coli O157:H7 from animal feed operations to produce fields or the surrounding environment. Overall, this project addresses strategic priority Section 3. Adjacent and Nearby Land Features and Activities, and the contribution of this project is twofold; these studies will 1) fill important gaps in our knowledge about the transmission of E. coli O157:H7 from a cattle operation onto adjacent lands via weather, and 2) result in critical industry guidance on how to assess environmental factors during the pre-harvest stage of production near cattle operations to best mitigate food safety risks.

Objective 1: Identify normal and extreme weather events associated with an increased risk of E. coli O157:H7 transmission from a cattle feedlot to the surrounding environment. 

Objective 2: Develop risk assessment models based on field proximity to animal operation and E. coli O157:H7 transmission via weather.

This project is ongoing. A final report will be provided when the project is finished.