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Advice to give on winter vomiting bug (norovirus)

elena elisseeva/dreamstime.comA. This sounds like it could be a case of norovirus infection which, according to the latest Health Protection Agency information, is on the increase — so far there are 72 per cent more cases than there were last year.1 In previous years the trend has been for cases to increase in January and the agency predicts that numbers will rise further in the next few weeks.

The virus (formerly known as Norwalk-like virus or Norwalk virus), can be divided into at least five genogroups. Those from group II, genotype 4, are responsible for many cases of gastroenteritis in humans.2 Outbreaks often occur in close environments, such as on cruise ships.

Although the commonly used term for norovirus is “winter vomiting bug”, diarrhoea is also a feature. The first sign of infection is usually sudden nausea, which may be followed by forceful (projectile) vomiting and watery diarrhoea. Other symptoms include abdominal cramps, headache, fever and aching muscles.

Diagnosis can be confirmed by stool sample, but this is unnecessary in most cases.The infection is not usually dangerous and symptoms tend to clear up after a couple of days.

Norovirus is highly contagious. Current NHS advice to people who think they have norovirus is to stay at home rather than visit their GP, in order to help prevent spreading the infection, although those with co-morbidities or who still have symptoms after a few days should contact their GP.3

A painkiller can be recommended to alleviate any fever or aches. Paracetamol is probably a better choice than ibuprofen or aspirin in this case, to avoid adverse effects on the gastrointestinal tract.4 Use of antiemetics and antidiarrhoeals is discouraged.5

Key points

  • Typical signs of norovirus infection are sudden nausea, followed by forceful vomiting or watery diarrhoea, or both. Symptoms tend to last a couple of days. Use of antiemetics and antidiarrhoeals is discouraged.
  • The main danger of infection is dehydration and oral rehydration sachets may be recommended, particularly for at-risk groups.
  • Those infected should stay away from work or school for 48 hours after the last attack of vomiting or diarrhoea.

Watch out for dehydration

The main risk of norovirus infection is dehydration, particularly if symptoms are severe.

Children under five years of age are considered at increased risk of dehydration if they pass six or more diarrhoeal stools in 24 hours or if they vomit three times or more in 24 hours.6 Babies under six months old are at particularly high risk.7 Dehydration in adults is more likely in old people.

In this case, the father should be advised to look out for the symptoms of dehydration. Initially these include passing little urine, dark urine, a dry mouth and lips, weakness, lethargy and irritability.

RB teaser

Both the mother and child should drink plenty of fluids (more than they would normally), avoiding fizzy drinks and fruit juices, which can worsen diarrhoea. Adults will require at least 200ml after each bout of diarrhoea or vomiting. (After vomiting it is recommended to wait five to 10 minutes  before drinking slowly — small sips every few minutes.)

Oral rehydration therapy may be recommended to reduce the risks of dehydration. The summary of product characteristics for Dioralyte suggests the following quantities for fluid and electrolyte loss in diarrhoea:

  • One to one and a half times the usual 24 hour feed volume in infants up to two years
  • 200ml after every loose motion in children over two
  • 200–400ml (ie, one or two sachets) after every loose motion in adults

An oral syringe may be helpful for administering fluids slowly to children. Home-made salt or sugar drinks should be avoided.

Eat or fast?

It is not necessary to avoid eating and current advice is to eat small light meals if able. Fasting in children and babies is not considered appropriate unless a child is clinically dehydrated and being treated for dehydration.

Children should be encouraged to eat where possible but may have a reduced appetite. Getting enough fluid is most important. Breastfed babies should continue to be breastfed and bottle-fed babies should be given normal strength feeds.7

Other helpful advice

Norovirus is typically spread by the faecal-oral route. It can be caught by eating contaminated food or touching contaminated objects. To prevent its transmission, towels should not be shared and hands should be washed and dried after going to the toilet, vomiting or changing nappies and before preparing food or eating. Toilet seats, flush handles and taps can be disinfected with household bleach. People with norovirus should stay away from school or work until at least 48 hours after the last bout of diarrhoea and vomiting. In particular, they should also not visit hospitals during this time.

A person can be infected with norovirus several times because the virus is always changing and immunity is probably genotype specific. Research into a norovirus vaccine is ongoing.

About the author

Lin-Nam Wang, MRPharmS, is a community pharmacist and senior contributions editor at The Pharmaceutical Journal.

Citation: The Pharmaceutical Journal DOI: 10.1211/PJ.2013.11114317

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