Investigation on Norovirus Occurrence in Foodstuffs during the Years 2010-2020

Norovirus is a non-enveloped and single-stranded positive RNA virus belonging to the family Caliciviridae that affect a wide range of mammalian species including humans, dogs, cats, pigs, sheep, and cattle. The human Norovirus is reported as the main non-bacterial cause of foodborne outbreaks among people of all age groups worldwide. It is estimated that 212,000 individuals die from such infection every year, especially in the developing countries. The clinical symptoms occur after an incubation period of 24-48 hours and are characterized by nausea, sudden onset of vomiting and/or watery non-bloody diarrhea, abdominal or general muscle pain, headache, and mild fever. More severe conditions, i.e., dehydratation, hospitalization and potential death, have been also described in vulnerable groups, such as children and elderly. The main infection routes include person-to-person transmission, ingestion of contaminated water or food, fomites, and the environment. In the year 2020, the Rapid Alert System for Food and Feed reported a total of 58 notifications of foods contaminated by Norovirus, distinguished according to the food category in 50 deriving from bivalve molluscs (oysters and clams) and the remaining 8 from fruits and vegetables, such as frozen raspberries, frozen forest fruits, and pre-packaged iceberg lettuce. Among them, 11 were associated with foodborne outbreaks caused or suspected to be caused by Noroviruses. The most represented country of origin was France, while Italy was the notifying country with 35.5% of notifications. This chapter will investigate the liaison between the contaminated foods and occurrence of illness in consumers, with the objective to provide a picture of reports during the years 2010-2020. Some preventive strategies will be also described. In live bivalve molluscs, depuration or relaying, as well as cooking, pasteurization, freezing, or high-pressure processing can be performed, while in foods that are consumed without any treatment, irradiation, chlorine sanitization or disinfection with other chemicals are described.