Royal Free London NHS Foundation Trust
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Norovirus

General Information for Patients and Visitors

What is norovirus?

Norovirus is the most common cause of infectious diarrhoea and vomiting in the UK. It is also known as Norwalk virus or Small round structured virus and the illness it causes is often known as Winter vomiting disease. As the name suggests, the infection is much more common in the winter months, but it can occur at other times of the year.

Norovirus is highly infectious and spreads easily among people. Norovirus is not a hospital infection as such: the infection affects a lot of people in the community and outbreaks have been known to occur in workplaces, schools, hotels, cruise ships and in other situations where people congregate in a confined space. Up to 1 million people in the UK are thought to be affected by norovirus every year.

Norovirus

If it is brought into the hospital environment by someone incubating the infection, then it can easily spread to vulnerable hospital patients and also to staff. Norovirus is known to cause large outbreaks of infection in hospital which results in a lot of patients and staff being affected; wards often need to be closed in order to prevent spread. This has a huge detrimental affect on care provision. Hospitals, therefore, have very strict policies in place to control the spread of norovirus.

What are the symptoms of norovirus?

The incubation period is 24-72 hours. This is the time between catching the virus and developing symptoms

The symptoms usually start with the sudden onset of severe vomiting. This can be so forceful that it is termed ‘projectile vomiting’. Other symptoms include diarrhoea and stomach cramps.

The symptoms usually last for 24-48 hours, but most people feel ‘washed out’ for a few days after symptoms have settled.

There are no long term affects from norovirus and, even in the frail and the elderly, most people make a full recovery.

People remain highly infectious for at least 48 hours after symptoms have settled and may still excrete virus for 2 weeks after the illness. This makes transmission very difficult to control.

Unfortunately, immunity is short-lived. This means that even if a person has had norovirus in the past they may still get re-infected.

Is there any treatment?

There is no specific treatment to kill the virus. Fluid replacement by drinking plenty of clear fluids or giving fluid via a ‘drip’ will avoid dehydration.

How can you catch norovirus?

Norovirus can spread very easily from one person to another and only a very small amount of the virus is needed to cause infection. It may be caught:

  • Being exposed to virus in the vomit or diarrhoea of an infected person eg. when cleaning up.
  • Not washing hands after using the toilet.
  • Touching surfaces (such as toilet seats, bed rails, furniture) that have virus on them
  • From food that has been contaminated eg. oysters are commonly contaminated from sewage polluted sea.
  • By breathing in virus that remains in the air for some time after projectile vomiting.

How is norovirus prevented in hospital?

Because the virus spreads so easily and can be spread via people who are asymptomatic, it is impossible to prevent all norovirus infection in hospital. Instead, we concentrate on measures that will reduce the chance of the virus spreading.

  1. Good hand washing with soap and water is the key to preventing norovirus from spreading. Alcohol handgel does not kill norovirus.
    • Staff should clean their hands before and after touching any patient but it is particularly important that they wash their hands with soap and water after tending to a norovirus patient to prevent it spreading to other patients via their hands.
    • Visitors should wash their hands with soap and water after visiting a ward which has norovirus and they should not interact with other patients other than the person they’ve come to visit.
    • Staff and visitors should wash their hands before handling food and after visiting the toilet.
  2. Isolating patients with the virus. Patients with norovirus will be isolated from non-infected patient. The infected patient will normally be placed in a single room, but if there are a few cases of infection on the ward, infected patients will be nursed in adedicated bay. If there are a large number of cases, the ward may be closed to new admissions. Visiting may also be restricted to prevent visitors getting the infection.
  3. Cleaning. Enhanced cleaning using bleach-containing products is needed to eradicate norovirus from the environment. Vomit and diarrhoea must be cleaned up immediately and general ward cleaning will be increased.
  4. Symptomatic people must stay away from hospital. Staff and visitors who develop symptoms must not come into the hospital and they must remain away from the hospital until they have been free of symptoms for 48-72 hours. Staff must be cleared by occupational health before returning to work.

Further information

Further information on norovirus can be found at www.hpa.org.uk

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page last reviewed: 10 March 2010