Evaluation of F-specific RNA coliphages as markers of enteric viral pathogens on fresh produce

Since contaminated produce have caused several large disease outbreaks, concerns about the microbial safety of fresh produce have increased steadily. The issuance of produce safety guidance and the voluntary adoption of Hazard Analysis and Critical Control Points (HACCP) systems by the produce industry have resulted in a reduction in the frequency of produce associated outbreaks. However, because of our limited understanding of the ecology and transmission of viruses and protozoan pathogens, there is little assurance that current safety measures offer acceptable levels of protection from produce associated outbreaks caused by those pathogens. Gaps in scientific knowledge have precluded the development of food safety objectives, performance standards, and microbiological criteria that would help ensure the microbial safety of fresh produce that enters the United States market. Validated and standardized methods for detecting virus and protozoan pathogens in foods such as fresh produce are not yet available; and thus, scientific health risk assessment and produce safety criteria based on detection of these pathogens is not feasible. A system for monitoring and assessing the virological status of produce entering the United States food market is needed, but direct detection of viruses in non-clinical settings is an extremely difficult and time-consuming feat, and is generally unsuccessful. There is a growing body of evidence that FRNA phages could play a useful role as an index of enteric virus contamination of fresh produce, or as an indicator of produce sanitizing efficacy. This thesis project represents the first use of a surrogate virus to compare the survival of a major enteric viral pathogen (NoV) and its potential indicators FRNA phages and E. coli on fresh produce.