What is the risk from wild animals in food-borne pathogen contamination of plants?

Abstract

Fresh fruits, nuts and vegetables are increasingly linked to food-borne illnesses, outbreaks and recalls. The trend represents a modern-day public health conundrum wherein consumers are encouraged to eat more fresh produce to help prevent chronic health problems such as obesity and heart disease, but at the same time consumption of contaminated produce can lead to potentially life-threatening acute food-borne disease. Identification of environmental sources responsible for the contamination of raw and minimally processed or fresh-cut plant commodities is necessary to develop prevention strategies. Produce-related outbreaks have been caused by faecal contamination of plants or surrounding watersheds following intrusion by wild or feral animals. A wild animal shedding a zoonotic food-borne pathogen could contaminate plants directly through faecal deposition or indirectly via faecal contamination of agriculture water or soil in contact with the plants. Owing to the low infectious dose of zoonotic enteric pathogens and the potential for attachment and possibly ingress into edible parts of plants, even a low level of contamination from faecal pathogens represents a significant public health concern. This review focuses on potential produce food safety risks from wild animals at the pre-harvest level, and downstream processes that may promote pathogen survival and amplification that could lead to human food-borne illnesses, outbreaks, and recalls. Microbe-plant interactions for the major zoonotic food-borne pathogens and higher risk plant commodities are reviewed. Finally, current guidelines and regulations to minimize risks related to wild animal activity in the production environment are summarized.Review Methodology: Databases used in this review included NCBI PubMed and the Center for Produce Safety Global Research Database. References from existing EndNote files and articles obtained from the database searches were also used to identify additional relevant material. Conference proceedings following two special sessions on wildlife and food safety held at the 23rd and 25th Vertebrate Pest Conferences were also reviewed. Produce and plant product safety regulations and guidance documents were found by searching agency/organization websites including the US Food and Drug Administration, Western Growers and the University of California Postharvest Technology online libraries.

Enteric Human Pathogens of Wild Boar, Feral Swine, and Javelina (Order: Artiodactyla)

“…The findings underscore the importance of continued public health education efforts to protect hunters from exposure to these pathogens when handling game animals. Fresh fruit and vegetable growers should continue to prevent intrusions by wild and feral animals in the produce production environment to minimize transport of fecal-borne pathogens to crops intended for human consumption (Jay andWiscomb 2008, Massei et al 2011).…”

“…There is increasing evidence that some wild ungulate species are important reservoirs of enteric human pathogens, and they may contribute to foodborne disease transmission directly through ingestion of undercooked game meat, and indirectly via fecal contamination of fresh fruit and vegetable crops or agricultural water sources (Langholz and Jay-Russell 2013). The enteric zoonotic bacterial foodborne pathogens of greatest concern with regard to food safety and wildlife include Campylobacter spp., Shiga toxin-producing Escherichia coli (STEC), and Salmonella enterica, although Yersinia enterocolitica, Y. pseudotuberculosis, and Listeria monocytogenes may also be shed in the feces (Jay-Russell 2013). This paper focuses on fecal-borne bacterial zoonoses, but wild boar and feral swine are also important reservoirs of other bacterial, parasitic, and viral pathogens that may be transmitted through ingestion of contaminated game meat and/or direct contact (e.g., Brucella, Cryptosporidium, Toxoplasma, Trichinella, Hepatitis E, etc.…”

Persistence of Escherichia coli in the soil of an organic mixed crop‐livestock farm that integrates sheep grazing within vegetable fields

“…Foodborne pathogens can be transmitted to humans directly through contact with faeces, or indirectly through contaminated water or produce and they can exist in the soil for extended periods of time (Franz, Schijven, Husman, & Blaak, 2014;Fraser, MacRae, Ogden, Forbes, & Strachan, 2013;Harris et al, 2013;Moriarty, Mackenzie, Karki, & Sinton, 2011;Ongeng et al, 2015). STEC is usually introduced into agricultural environments by livestock and/or wildlife faeces (Jay-Russell, 2013;Reed-Jones, Marine, Everts, & Micallef, 2016). Sheep are asymptomatic reservoirs of STEC and faecal shedding from ruminants may increase during periods of stress (Cooley et al, 2013;Edrington et al, 2009;Moynihan, Richards, Ritz, Tyrrel, & Brennan, 2013;Ongeng et al, 2014;Schilling et al, 2012).…”

Breeding Crops for Enhanced Food Safety

“…The fresh produce industry faces several major challenges related to controlling risks from in-field contamination of crops by zoonotic enteric pathogens (Beuchat, 1996;Cooley et al, 2007;Jay-Russell, 2013;Jeamsripong et al, 2019). First, zoonotic fecal-borne pathogens may be widespread in the environment, but rarely detected in field crop, thus making it difficult to precisely define the most important direct and indirect routes of contamination (e.g., agriculture water, animal intrusion, bioaerosols, soil amendments, etc.).…”