Winter Vomiting Disease

The so-called 'winter vomiting disease', also called ‘winter vomiting bug’, viral gastroenteritis or gastric flu, is a virus causing a stomach upset with vomiting and/or diarrhoea. It is most commonly caused by a virus known as the Norwalk-like Virus (NLV) or Small Round Structured Virus (SRSV). While the virus usually causes short-lasting outbreaks, it can be extremely infectious.

The incubation period is usually around 24-48 hours but may be as short as six hours.

What are the symptoms?

The first symptoms are often abdominal pain and nausea. These are then followed by vomiting and diarrhoea. The vomiting may be of sudden onset, severe, projectile and very tiring. The diarrhoea is usually quite mild. Other symptoms can include fever, headache and muscle aches. The illness is usually mild, lasting less than 2-3 days; however the symptoms can be quite unpleasant and debilitating in older people.

How is the disease spread?

Humans are the only known source of NLV. The virus is extremely contagious and may be spread by:

  • Person to person – primarily when a person who is ill vomits. When sudden projectile vomiting occurs, a fine mist of virus particles passes into the air and can be readily spread to others in a wide area. This is particularly common in hospitals and nursing homes. Contamination can also occur through transfer of the virus onto people’s hands.
  • Infected food handlers – passing the virus on to people with whom they may come in contact.
  • Water – drinking water that is contaminated and not properly treated may transmit the virus, as may contaminated ice-cubes and swimming in or brushing teeth with contaminated water.
  • Contaminated food – often shellfish, but also fruit and salads that have been washed with contaminated water.

The NLV virus can also remain infectious for several days on surfaces and in fabrics and upholstery. Thorough decontamination to remove the virus from soiled surfaces and furnishings is therefore necessary.

How common is winter vomiting disease?

There have been a number of outbreaks of winter vomiting disease in Ireland in recent years, as well as similar outbreaks around the world. Better detection and reporting may explain some of the increase in reports of the illness.

Although mild, an outbreak of the illness can have serious economic consequences, closing hospitals, hotels and other services. Recent outbreaks in hospitals in Ireland show how infectious this virus can be. While the illness is mild, outbreaks can result in hospitals having to close for disinfection and staff being unable to work while they are unwell, often resulting in the cancellation of non-essential operations and procedures.

What should I do if I have winter vomiting disease?

Medications are not normally necessary for winter vomiting disease and as the disease is caused by a virus, antibiotics are ineffective. The affected person normally recovers without medical treatment within a few days. It is important to ensure that you drink plenty of fluids to prevent dehydration.

The most important thing is to prevent the virus from spreading to others.

Good personal hygiene is essential, especially if you are suffering from diarrhoea or vomiting. Frequent hand washing with hot water and soap for at least 20 seconds is a very effective way of limiting the spread of all bacteria and viruses that cause gastroenteritis. It is essential for those looking after elderly people, babies and small children and people who have difficulty with personal hygiene.

The Irish Health Protection Surveillance Centre (HPSC) advises that you should wash your hands:

In the bathroom

  • After using the toilet or touching surfaces in the bathroom.
  • After changing nappies - wash the child's hands also.
  • After helping a child go to the toilet.
  • Whenever your hands have come contact with vomit, saliva and runny noses.

In the kitchen

  • Before preparing or eating food, especially food that does not need any further cooking.
  • After touching raw meat, poultry, fish or eggs.
  • After meals and snacks.


  • After touching any animals, even your own pets.
  • After working or playing in the garden.
  • After touching bins and other waste.
  • Whenever your hands are dirty.

It is very important that people who have been ill with vomiting or diarrhoea should stay out of work for at least 2 full days and preferably 3 days after their symptoms have stopped. This and thorough handwashing are two of the very best ways to prevent the spread of the winter vomiting disease.

Reviewed: November 2, 2006