Most are caused by Norwalk-like viruses, but we need to know more about these

Media attention on outbreaks of infection caused by salmonella species and Escherichia coli 0157 and more recently on new variant Creutzfeldt-Jakob disease have highlighted the importance of foodborne transmission of infectious agents, but what of the role of viruses? A recent report from the Advisory Committee on the Microbiological Safety of Food (ACMSF) provides a timely reminder of the importance of these agents, points to gaps in our knowledge, and offers advice for their control.1

Although the list of viruses causing intestinal disease in humans is long, the epidemiology of foodborne outbreaks in the United Kingdom reveals the predominance of a single group, the Norwalk-like viruses.2 Also known as small round structured viruses, these are an antigenically diverse group of caliciviruses which have similar morphology under the electron microscope and appear to cause an identical clinical picture of projectile vomiting and diarrhoea. They include Hawaii, Snow Mountain, Taunton, Mexico, and Grimsby viruses.3 4

Norwalk-like viruses can cause illness at any age, possibly due to their antigenic diversity but also because infection appears …