Q&A: What is norovirus?

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Q & A: What is norovirus? from Times Online January 3, 2008

As a virulent gastric bug affects more than 100,000 a week, the Health

Protection Agency explains what it is

What are noroviruses?

Noroviruses are a group of viruses that are the most common cause of

gastroenteritis (stomach bugs) in England and Wales. In the past,

noroviruses have also been called " winter vomiting viruses " , " small

round structured viruses " or " Norwalk-like viruses " .

How does norovirus spread?

The virus is easily transmitted from one person to another. It can be

transmitted by contact with an infected person; by consuming

contaminated food or water or by contact with contaminated surfaces or

objects.

What are the symptoms?

The symptoms of norovirus infection will begin around 12 to 48 hours

after a person becomes infected. The illness is self-limiting and the

symptoms will last for 12 to 60 hours. They will start with the sudden

onset of nausea followed by projectile vomiting and watery diarrhoea.

Some people may have a raised temperature, headaches and aching limbs.

Most people make a full recovery within one to two days, however some

people (usually the very young or elderly) may become very dehydrated

and require hospital treatment.

Why does norovirus often cause outbreaks?

Norovirus often causes outbreaks because it is easily spread from one

person to another and the virus is able to survive in the environment

for many days. Because there are many different strains of norovirus,

and immunity is short-lived, outbreaks tend to affect more than fifty

percent of susceptible people. Outbreaks usually tend to affect people

who are in semi-closed environments such as hospitals, nursing homes,

schools and on cruise ships.

How can these outbreaks be stopped?

Outbreaks can be difficult to control and long-lasting because

norovirus is easily transmitted from one person to another and the

virus can survive in the environment. The most effective way to

respond to an outbreak is to disinfect contaminated areas, to

institute good hygiene measures including hand-washing and to provide

advice on food handling. Those who have been infected should be

isolated for up to 48 hours after their symptoms have ceased.

How is norovirus treated?

There is no specific treatment for norovirus apart from letting the

illness run its course. It is important to drink plenty of fluids to

prevent dehydration.

If I'm suffering from norovirus, how can I prevent others from

becoming infected?

Good hygiene is important in preventing others from becoming infected

– this includes thorough hand washing before and after contact. Food

preparation should also be avoided until three days after symptoms

have gone altogether.

Who is at risk of getting norovirus?

There is no one specific group who are at risk of contracting

norovirus – it affects people of all ages. The very young and elderly

should take extra care if infected, as dehydration is more common in

these age groups.

Outbreaks of norovirus are reported frequently in semi-closed

institutions such as hospitals, schools, residential and nursing homes

and hotels. Anywhere that large numbers of people congregate for

periods of several days provides an ideal environment for the spread

of the disease. Healthcare settings tend to be particularly affected

by outbreaks of norovirus. A recent study done by the Agency shows

that outbreaks are shortened when control measures at healthcare

settings are implemented quickly, such as closing wards to new

admissions within four days of the beginning of the outbreak and

implementing strict hygiene measures.

How common is norovirus?

Norovirus is not a notifiable disease so reporting is done on a

voluntary basis. The HPA only receives reports of outbreaks and we see

between 130 and 250 outbreaks each year. It is estimated that

norovirus affects between 600,000 and a million people in the UK each

year.

Are there any long-term effects?

No, there are no long-term effects from norovirus.

What can be done to prevent infection?

It is impossible to prevent infection, however, taking good hygiene

measures (such as frequent hand washing) around someone who is

infected is important. Certain measures can be taken in the event of

an outbreak, including the implementation of basic hygiene and food

handling measures and prompt disinfection of contaminated areas, and

the isolation of those infected for 48 hours after their symptoms have

ceased.

Source: Health Protection Agency, an umbrella authority set up in 2003

to connect government public health authorities and organisations.

http://www.timesonline.co.uk/tol/life_and_style/health/article3126026.ece