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Norwalk virus,

highly contagious viral disease caused by infection with an RNA virus of the genus Norovirus. The virus causes acute gastroenteritis, usually one to two days after infection; typical symptoms are abdominal pain and cramps, diarrhea, vomiting, and a low-grade fever. Dehydration may result if enough liquids are not consumed to replace lost fluids. There is no treatment for norovirus, which usually lasts one to three days and does not result in severe illness, but it may become life-threatening if an infected person becomes dehydrated. Dehydration may be treated by administering fluids intravenously. A person typically remains contagious for several days after the acute illness has ended.

Norovirus is transmitted by the fecal-oral route, most commonly through person-to-person contact a result of poor hygiene or through food contaminated by an infected food preparer or handler. Ingestion of uncooked shellfish harvested from contaminated waters or of contaminated drinking water may also transmit the disease. Outbreaks most commonly occur in settings where individuals are in close quarters, such as hospitals, nursing homes, and retirement homes, vacation resorts and cruise ships, and child-care centers and schools, and spread rapidly; most epidemic viral gastroenteritis is caused by a Norovirus. The virus can persist in the environment on some surfaces for a relatively extended period of time, and is resistant to disinfection by alcohol- or detergent-based agents, but soap and water is effective in blocking the spread of the disease. The disease was first identified as result of an outbreak in a Norwalk, Ohio, elementary school in 1968.

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The main aim is to help prevent and control the spread of norovirus in residential care homes during the winter.
Norovirus generally causes mild gastrointestinal symptoms such as vomiting and diarrhoea.
Lopman and colleagues analysed 175 published reports to compile data on the prevalence of norovirus in individuals with acute gastroenteritis between 1990 and 2014.
The case definition for norovirus illness was acute onset of nausea, vomiting, or diarrhea (i.
Alice Casey, Cardiff and Vale Health board's chief operating of-ficer, said that while norovirus is extremely common in the community at this time of year, it can present problems when it spreads in hospitals.
Also, fewer subjects in the vaccine group shed norovirus at day 10 after the challenge (22.
A spokeswoman for the Food Standards Agency said: "Following detailed and constructive discussions, during which many different views were expressed, it was agreed that no limits should be set at this stage due to the limitations of the current methodology and the gaps in current knowledge about norovirus.
In the laboratory, the pesticide solutions were spiked with one of two clinical strains of norovirus isolated from stools of infected people (hNoV GI.
The norovirus is highly contagious, and a new strain of the stomach bug is even more likely to affect large groups of people.
Once you have caught norovirus you are immune to the illness for around 14 weeks.
com An unknown illness, suspected of being a norovirus, has sickened 194 passengers and 11 crew members aboard the luxury ship Queen Mary 2 cruising in the Caribbean, causing vomiting and diarrhea, federal health officials said in New Yorkon Friday.
The number of laboratory confirmed cases of norovirus is 83% higher than the same time last year, the Health Protection Agency (HPA) said.