Norovirus in fresh and frozen produce on retail sale
Recently published Food Standards Agency (FSA) research on foodborne viruses included a large retail survey conducted in 2015-16. It showed that 5.3% of lettuce, 2.3 % of fresh raspberries and 3.6% of frozen raspberries, tested positive for Norovirus, a food safety concern. The publication of this data received widespread media attention in December.
It is the first and only prevalence survey of its kind to have been performed in the UK. The survey, which was conducted over the course of a year, analysed produce sold by retailers, including UK supermarkets, wholesalers and other outlets. It sets a useful benchmark for monitoring Norovirus contamination of produce. This benchmark data will be useful for evaluating conformance to industry standards (e.g. Global GAP). Public Health England (PHE) statistics for the year 2015-2016 (when the study was performed) showed that it was a lowincidence year for Norovirus illness in the community.
Why the lack of prevalence data?
Major prevalence studies like this do not occur often as they can be logistically very challenging and require significant resources / funding. Also, information on positive samples is already available via reports entered on the EU Rapid Alert System for Food and Feed (RASFF) system, which originate mainly from routine monitoring of samples by individual companies or as demanded by local authorities. This EU information suggests that a zero-tolerance stance is usually taken in the event the virus is detected, with actions including withdrawal from the market, detention by operator and recall from consumers.
No routine monitoring of fresh and frozen produce for the presence of Norovirus (or Hepatitis A Virus) is performed in the UK, therefore no prevalence data has been available to help companies and retailers introduce risk mitigation strategies. The FSA study has gone some way to filling the data gap associated with this combination of risks and commodities.
What can you / should you do if you grow, harvest, distribute and sell these types of food?
Currently, in the UK there are no regulations or microbiological criteria in place for viruses in foods, over and above the general requirement for food to be safe – mainly being due to the lack of prevalence data available.
The new survey data (from a low incidence year) can be used to benchmark where producers / suppliers rank in relation to this new data set. It can also be useful to undertake monitoring at various critical points in the supply chain. If it revealed an issue with produce at harvest, checks would need to be carried out to ensure that all procedures were being rigorously adhered to (for example, good agricultural practices and good hygienic practices), in addition to ensuring that irrigation water quality was monitored regularly. Critical points can include where produce is processed, such as for berries which are frozen, or at point-of-sale, where additional handling may take place.