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Norwalk viruses
Last reviewed: 04.07.2025
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In 1968, during an outbreak of acute gastroenteritis among schoolchildren and teachers in the city of Norwolk (USA), the causative agent of this outbreak was discovered - a virus called Norwolk. It was identified using the method of immune electron microscopy. The virus has a spherical shape and a diameter of 27-32 nm. Similar viruses were discovered in many other outbreaks of gastroenteritis in England, the USA, and Australia.
Antigenically, they were found to be heterogeneous, with at least 4 serovariants identified. The genome is represented by single-stranded, non-fragmented RNA of positive polarity. The virus is classified as belonging to the Caliciviridae family; these are the most common causative agents of gastroenteritis in children over 4 years of age and in adults. The virus is excreted in the first 48-72 hours after the disease, and is very stable in the external environment. It is spread by the fecal-oral route through contaminated water and food.
The incubation period is 18-48 hours. The onset of the disease is acute, vomiting in 70% of cases, diarrhea in 65%. The disease lasts 2-3 days. In elderly people, a fatal outcome is possible. Diagnosis of the disease is difficult due to the lack of laboratory test systems and the impossibility of culturing the virus in vitro.
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