Virological fit-for-purpose risk assessment in a leafy green production enterprise

The purpose of the study was to provide an example of integrated monitoring and control of foodborne viruses using the assessment of one vertical production enterprise and the recommendations given to it. A risk assessment for virological hazards in lettuce was carried out based on the Codex Alimentarius framework, modified to consider viral hazards associated with fresh (whole) lettuce. The fit-for-purpose model was constructed by a complex process of: 1) identification of premises-selection of sampling sites, through the analysis of background information questionnaires based on HACCP audit principles and food safety fact-finding visits, 2) development of sampling guidance documents, 3) a half-year sampling campaign, 4) molecular analysis of the presence of index, human adenoviruses (hAdV) and human pathogenic viruses, noroviruses (NoVGI, NoVGII), and hepatitis A virus (HAV), 5) fit-for-purpose risk assessment, 6) development of a fit-for-purpose guidance sheet for the enterprise food safety manager for the prevention of contamination of leafy greens by viruses. Molecular virological analysis resulted in the detection of hAdV (55.65%, 123/221), and NoVGII (16.66%, 4/24), while NoVGI (0/55) and HAV (0/60) were not detected in the analyzed samples. HAdVs were detected in samples of all three phases (production, processing, and point of sale). The elevated prevalence of hAdVs supports the existence of routes of produce viral contamination. NoVs GI were detected at the point of sale in fresh lettuce heads, supporting the previous finding that pathogenic viruses can follow the routes of index viruses. NoVs GII were detected in irrigation water, harvestersʹ hands and manure samples, indicating sewage contamination of water, and unsatisfactory levels of hygiene concerning hands hygiene and use of toilet facilities. As a result of the study a fit-for-purpose guidance sheet was finally produced for the prevention of contamination of leafy green vegetables by viruses. The integrated monitoring and control process of the study can be applied to all leafy green vegetables production sites.