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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR BIOLOGY AND GENOMICS OF FOODBORNE PATHOGENS

Location: Produce Safety and Microbiology Research

Title: Enteric human pathogens associated with fresh produce: sources, transport and ecology.

Author
item Mandrell, Robert

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: August 10, 2008
Publication Date: September 1, 2009
Citation: Mandrell, R.E. 2009. Enteric human pathogens associated with fresh produce: sources, transport and ecology. In: Fong, X., Niemira, B.A., Doona, C.J., Feeherry, F.E., Gravani, R.B., Editors. Microbial Safety of Fresh Produce. Ames, Iowa: Blackwell Publishing: pgs:5-41.

Interpretive Summary: The consumption of fresh fruits and vegetables has been growing in the United States and other western countries due to their health benefits and the year-round availability of many produce commodities. However, the increase in consumption has correlated with an increase in foodborne outbreaks associated with fresh produce contaminated with bacterial, viral or protozoal pathogens. The commodities implicated most frequently have been leafy greens (lettuce, cabbage, mesclun mix, spinach), greens-based salads, sprouts and tomatoes. Numerous recent outbreaks associated with these commodities have been caused by contamination with either Salmonella enterica or Escherichia coli O157:H7. Potential sources of pre-harvest contamination seem logical (livestock manure, human or wild animal feces, irrigation water), however, definitive information about pathogen fate and transport processes relevant to produce contamination has been lacking. Various biotic and abiotic processes link primary environmental pathogen reservoirs to fields by dynamic and transient processes including animal vectors and watersheds, and possibly other transport processes or routes of dissemination. Processes that result in contamination of produce with potential infectious doses of pathogens are important to identify and eliminate. This chapter will present a review of the results of laboratory and field studies of enteric pathogen incidence, survival and transport relevant to pre-harvest contamination of fresh produce.

Technical Abstract: The consumption of fresh fruits and vegetables has been growing in the United States and other western countries due to their health benefits and the year-round availability of many produce commodities. However, the increase in consumption has correlated with an increase in foodborne outbreaks associated with fresh produce contaminated with bacterial, viral or protozoal pathogens. The commodities implicated most frequently have been leafy greens (lettuce, cabbage, mesclun mix, spinach), greens-based salads, sprouts and tomatoes. Numerous recent outbreaks associated with these commodities have been caused by contamination with either Salmonella enterica or Escherichia coli O157:H7. Indeed, more that 20 leafy green-associated outbreaks occurring between 1995 and 2008 were due to E. coli O157:H7 contamination, and 12 of the outbreaks were traced to produce grown in or near the Salinas Valley of California. Moreover, investigations revealed that pre-harvest contamination was responsible for at least some of the outbreaks. Similarly, recent S. enterica outbreaks associated with lettuce, and recurrent outbreaks associated with tomatoes, cantaloupes and raw almonds also appear consistent with a scenario of pre-harvest contamination. Potential sources of pre-harvest contamination seem logical (livestock manure, human or wild animal feces, irrigation water), however, definitive information about pathogen fate and transport processes relevant to produce contamination has been lacking. Various biotic and abiotic processes link primary environmental pathogen reservoirs to fields by dynamic and transient processes including animal vectors and watersheds, and possibly other transport processes or routes of dissemination. Processes that result in contamination of produce with potential infectious doses of pathogens are important to identify and eliminate. The results of laboratory and field studies of enteric pathogen incidence, survival and transport relevant to pre-harvest contamination of fresh produce will be presented and discussed.

Last Modified: 9/20/2014
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