KEY TAKEAWAYS:
- Two-year project is examining E. coli O157:H7 transmission from an animal feeding operation based on weather and field proximity.
- Sample sites are located at varying distances from a 6,000-head cattle feeding operation.
- Weather data, including for major storms, will be collected from on-site stations.
- Data will be used to develop risk-assessment and predictive models for potential produce contamination based on positive samples, persistence and field location.
Referenced CPS Research:
While nearby concentrated animal feeding operations (CAFOs) have been suspected in a few E. coli O157:H7 produce outbreaks, little data exists about how far potential contamination risks may extend and weather’s role.
To fill in some of the knowledge gaps, Kerry Cooper, Ph.D., at the University of Arizona, is leading research to develop a risk-assessment model of E. coli O157:H7 transmission from an animal operation to adjacent land based on environmental conditions and field proximity.
His two-year project is essentially a proof of concept. But Cooper said he hopes in the future to build a user-friendly model producers could use to guide risk assessments of produce fields near animal operations.
“Initially we’re going to have a model to give some guidance in a general sense to everybody, with the idea that we’re going to move forward to eventually create something like an app, and I think an app is going to be ideal,” Cooper said.
Joining him as co-investigators are Erika Austhof, Ph.D., at the University of Arizona, and Jim Bono, Ph.D., with the U.S. Department of Agriculture’s Agricultural Research Service. Austhof brings expertise in computer modeling of foodborne pathogen transmission and weather.
Based at the U.S. Meat Animal Research Center (MARC) in Clay Center, Nebraska, Bono has extensive knowledge of the endemic E. coli O157:H7 strain within the center’s 6,000-head cattle herd as well as predominant wind patterns.
Although the MARC facility is far removed from most leafy green production, Cooper said it had several advantages that lent itself to research. For example, the USDA provides Cooper’s team complete access to the feedlot and cattle for sampling, something that would be impossible elsewhere.
The researchers established 24 sample sites radiating in eight directions from the feedlot center, with distances varying from 100 meters to 1,500 meters, or roughly a mile. Each site consists of two sets of soil, air, water and surrogate plant surface sampling.
Because it would be nearly impossible to cultivate a leafy green crop at the sites, Cooper said they tried to use a synthetic surface to act as a plant leaf stand-in. But the approach proved ineffective. In the meantime, the researchers are clipping vegetation at the sample sites to see if pathogens have colonized them.
“It’s not perfect, but we’re working on tweaking suggestions from the industry folks to come up with a better surface,” he said.
The researchers plan to collect samples every two weeks from May through September for two years. In addition, they’ll use whole genome sequencing to genetically compare the cattle E. coli O157:H7 strain to those in their samples to confirm transmission from the animal operation.
On the west end of the feedlot is a tree line, which Cooper said they’re also going to monitor to determine its potential role in pathogen dispersion.
At the suggestion of the CPS advisory committee, Cooper added student workers to collect flies possibly emanating from the feedlot and assay them for E. coli O157:H7 following protocols.
As part of the project, the researchers also will collect data from on-site weather stations and conduct enhanced sampling before and after extreme weather, such as flooding, high winds and severe storms. That data will be merged with additional drought and weather indices and wildlife migration information to assess other potential transmission sources.
The researchers will then use the information to develop risk-assessment and predictive models for potential produce contamination based on positive samples, persistence and varying distances from an animal feeding operation.
“We’re trying to gather some key data but also some predictive data to see how we can build off of this to help the industry,” Cooper said.
While the researchers are conducting their work with cattle, he said the general risk-assessment concepts should be applicable to other types of animal feeding operations.
“Our goal is hopefully to create a general model that shows (vegetable) producers what they need to be concerned about,” he said.