As part of a larger study, begun in January 2014, researchers for the UK’s Food Standards Association (FSA) have revealed the results of testing berry fruit and salad vegetables in the United Kingdom.
The NoVAS study aims to determine how much Norovirus is transmitted through contaminated food stuffs, what the role of infected food handlers in transmission is and whether or not it is possible to differentiate between infectious (intact) and non-infectious (damaged) Norovirus in a variety of food matrices.
Exactly 1,152 samples of fresh produce sold at retail in the UK were analysed for Norovirus. Of 568 samples of lettuce, 30 (5.3 percent ) were Norovirus-positive. Most (24 out of 30) lettuce samples which tested positive for Norovirus were grown in the UK and 19 of those 24 samples contained NoV GI.
Seven out of 310 (2.3 percent) samples of fresh raspberries were Norovirus-positive. Most (six out of seven) of the positively-testing fresh raspberry samples were imported, but no predominance of a geno-group, or any seasonality, was observed. Ten out of 274 (3.6 percent) samples of frozen raspberries were Norovirus-positive.
The country of origin of the positively-testing frozen raspberry samples was not identified in most (seven out of ten) instances. An FSA spokesperson said: “While the vast majority of the estimated 2.8 million illnesses each year caused by Norovirus are due to close contact between people and touching contaminated surfaces, a small percentage (around, on average, 2.5 percent) comes from contaminated food. “We know that outbreaks of Norovirus have been caused by consumption of contaminated oysters and fresh produce, such as berries and salad, as well as from those who handle food for others. “That’s why we’re funding a large study to find out more about how we can reduce the burden of the Norovirus illness in the UK through food. The results of this will be out next year. “The collected data adds to the currently limited body of prevalence information on Norovirus in fresh produce, and indicates the need for implementation of effective food safety management of foodborne viruses.