Norovirus infection

What is norovirus?

Norovirus is a virus that causes gastroenteritis. A person with norovirus usually gets better within 1 to 2 days without treatment.

Norovirus is sometimes called ‘winter vomiting’. This is because there are often more cases in winter than warmer months. In winter, people tend to stay together indoors. Some other common names for norovirus infection are:

• gastric flu
• stomach flu
• viral gastro

What are the symptoms of norovirus?

The main symptoms of norovirus are:

• vomiting
• nausea (feeling sick in your stomach)
• diarrhoea
• cramp-like stomach pain
• slight fever
• muscle aches

Symptoms usually appear 1 or 2 days after infection. They can develop more quickly, even as soon as 12 hours after.

Symptoms usually last for 1 or 2 days. They rarely cause long-term harm in people who are otherwise healthy.

Symptoms can be more severe and long-lasting in some groups of people. These include:

• elderly people
• young children
• people with a compromised immune system

A compromised immune system means it is harder to fight off infection. Examples of this are people who:

• are having treatment for cancer
• have an autoimmune disease and take immunosuppressants

If you or someone you care for has a severe gastroenteritis infection, seek medical or hospital care.

What causes norovirus?

Many viruses can cause gastroenteritis. Norovirus is the name of one group of viruses that cause the illness. It ‘s one of the more common gastroenteritis viruses.

Norovirus is highly contagious. This means it’s easily spread to other people.

The virus can be found on surfaces touched by the infected person. This can include:

• handrails
• door knobs
• chair handles

The virus can stay alive for long periods on surfaces.

Someone can catch norovirus from an infected person if they:

• touch the infected person’s vomit or faeces (poo)
• touch the infected person’s unwashed hands
• touch surfaces or objects that have been touched or used by the infected person
• breathe in virus particles that are in the air after someone has vomited
• eat food or drink water that has been contaminated by the infected person

Norovirus often causes gastro outbreaks in places where a lot of people work, play or live together. This can include:

• aged care facilities
• child care centres
• schools
• cruise ships

These are closed environments where lots of people mix with each other and spend time together.

Norovirus infection and outbreaks can also happen in restaurants and fast-food shops. Many people may become sick if a batch of food is contaminated by one infected person.

When should I see my doctor?

See your doctor if:

• your diarrhoea lasts for more than 2 days in an adult, or for more than 24 hours in a baby
• you get dehydrated
• you also have a fever
• you have severe pain in your abdomen (tummy) or rectum
• your diarrhoea is bloody or black

How is norovirus diagnosed?

Norovirus infection is usually diagnosed from your symptoms.

A formal diagnosis needs laboratory testing of your stool (poo) sample. Public health staff sometimes ask for stool samples to help manage an outbreak of illness.

How is norovirus treated?

The best treatment for a norovirus infection is rest. It’s also important to avoid dehydration. This is when you lose more fluid than you take in. Keeping hydrated is particularly important for elderly people and babies.

Keep hydrated by drinking plenty of fluids. You can buy oral rehydration solutions at a pharmacy.

If you don’t have a rehydration drink from the pharmacy, you can drink diluted, clear fruit juice or cordial.

It must be mixed with water as juice, soft drink and cordial contain a lot of sugar. This can make diarrhoea worse.

You can have these drinks diluted:

• Juice or soft drink — mix 1 part drink to 4 parts water (for example, 40 ml of the drink with 160 ml water)
• Cordial — mix 1 part cordial to 20 parts water (for example, 5 ml cordial with 100 ml water)

There is no medicine or antibiotic to treat norovirus. You should only use anti-vomiting or anti-diarrhoeal medicines if your doctor has told you to use them.

How is norovirus prevented?

Norovirus is easily spread to other people. Good hygiene is very important.

To help prevent infection:

• wash your hands with soap and running water after using the toilet or changing nappies
• wash your hands with soap and water before eating or handling food
• wash your food before eating, especially oysters and shellfish, and fruits and vegetables
• wash your bedding and clothing if they are stained by diarrhoea or vomit
• wipe down household surfaces and disinfect with a diluted bleach-based cleaner
• clean contaminated soft furnishings or carpet with hot water and detergent followed by a steam clean

You will still be contagious for a couple of days after the diarrhoea or vomiting has stopped.

You should stay away from work until 48 hours (2 days) after your symptoms have stopped. Infected children should also stay home from school or childcare until 48 hours after symptoms have disappeared.

There is no vaccine to prevent norovirus infection.