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Istituto Superiore di Sanità
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Epidemiology for public health - ISS

First isolated and discovered in 1972, noroviruses belong to the Caliciviridae family of single-stranded RNA viruses, and are among the most common agents of non-bacterial acute gastroenteritis. As a result, they pose a serious threat to food safety. They are sometimes referred to as Norwalk virus, after the city in Ohio where an outbreak of gastroenteritis started in 1968. Norovirus infections mainly occur in community settings, hospitals, nursing homes, schools or enclosed environments, such as merchant ships and cruise ships. Noroviruses are not culturable, which led to diagnostic problems in the past. Until a few years ago, they could be identified only with an electronic microscope, due to their tiny size, or by measuring the presence of antibodies in the blood. Over the last ten years, rapid diagnostic tests have been developed, using molecular markers or commercial Elisa (Enzyme-Linked Immunosorbent Assay) kits, to detect the virus in biological samples. Three norovirus genogroups (GI, GII and GIV) are currently known to infect humans. These genogroups can be further divided into over 30 genotypes.


Publication date: 28 January 2021