Food safety experts from the UK's Food Standards Agency (FSA) have also detected the norovirus bug in one in every 27 bags of frozen raspberries.
"Norovirus is the commonest cause of gastrointestinal disease in the UK causing millions of cases annually. One should not expect to find a norovirus in one's lettuce or raspberry," researchers told the Sunday Times, noting negligence by food suppliers and retailers.
The pathogen entering the food supply chain is the consequence of guidance on food hygiene not being adhered to, they added.
The National Health Service (NHS) explains that the bug can be spread when there is close contact with someone with norovirus, when a person touches surfaces or objects that have the virus on them and then touching their mouth, as well as when one eats food that's been prepared or handled by someone with norovirus.
The finding by researchers raised concerns that the vomiting bug could also be possibly prevalent in other fresh produce.
Norovirus, which can't be killed by alcohol hand gels, takes up to 300 lives every year.