Viruses implicated in ‘gastric flu’ include the ‘winter vomiting bug’ norovirus and rotavirus, and less commonly adenovirus, astrovirus, and sapovirus. Viruses can be foodborne or inhaled, but norovirus is usually transferred into the mouth by a hand having touched a contaminated item; faecal-oral transmission is typical. The general term for an inanimate object carrying an infectious agent is a ‘fomite’.3,12,13

Public health laboratories differentiate between 15 of at least 28 different norovirus genocluster strains or genotypes. While norovirus is one of the most common causes of foodborne illness, it has been difficult to study as it is difficult to grow human norovirus in vitro and there is no suitable animal model. Norovirus evolves rapidly, and since 2001, five major GII.4 strains (the most common UK type) have emerged with significant antigenic changes, hampering vaccine development.14,15,16

Rotavirus is the major cause of gastroenteritis in infants and young children, and can have serious implications due to an increased risk of becoming severely dehydrated.17