Ecology And Epidemiology Of Salmonella And Listeria Monocytogenes In New York State Produce Production Environments

Abstract

Foodborne pathogen contamination of produce in the preharvest environment continues to present a considerable challenge and can lead to recalls or even outbreaks. Thus, there is a need for further development of science-based approaches to assist growers in minimizing the risk of preharvest contamination of produce. Salmonella and Listeria monocytogenes are two foodborne pathogens of concern in produce that both cause severe illness in humans. In these studies, we employed several approaches to model Salmonella and L. monocytogenes contamination in the preharvest environment as an ecological process. Specifically, the studies presented here investigated (i) the use of Geographical Information Systems (GIS) modeling to predict pathogen prevalence based on landscape and meteorological factors, (ii) the association between pathogen presence and field management practices to quantify likelihood of preharvest contamination, and (iii) the application of subtyping-based source tracking of pathogens in the preharvest environment. We observed that Salmonella and L. monocytogenes prevalence was not uniform across croplands, and that prevalence in a specific area may be significantly higher based on specific factors. For example, the localized prevalence of L. monocytogenes was higher in areas close to water. We also showed that Salmonella and L. monocytogenes isolation in fields was significantly influenced by specific management factors and that many of those factors were time dependent. For instance, application of manure to a field within a year increased the odds (OR=16.7, 95% CI=3.0, 94.4) of a Salmonella-positive field. Lastly, we found that Salmonella serotypes were diverse in the preharvest environment, and that PFGE type varied based on geographic region. Collectively, these findings suggest that risk management of pathogen contamination in the preharvest environment requires tailoring to each specific farm, as each farm has a unique set of factors that influence the risk of contamination. Knowledge of such factors for a farm will allow growers to prioritize risks. The ability to prioritize risks on produce farms will develop a preventative approach to preharvest food safety. Produce growers will be able to target areas within their farms that are at high risk for contamination, or implement more informed field management practices to reduce potential contamination of produce.