A highly contagious virus that causes sudden vomiting and diarrhoea and spreads easily through infected food handlers and contaminated food.
Most often through an infected food handler who prepares food while sick or too soon after recovering, spreading the virus from unwashed hands. It can also come from contaminated water or shellfish such as oysters grown in polluted water.
They should not handle food while they have symptoms and should stay away until at least 48 hours after vomiting and diarrhoea have stopped, following state health guidance. The virus can still be shed for a time after feeling better.
Alcohol-based sanitisers are less effective against norovirus than thorough handwashing with soap and running water. Proper handwashing is the key defence, especially after using the toilet and before handling food.
Symptoms usually start 12 to 48 hours after exposure and last one to three days. Most people recover fully, though young children and older adults need to watch for dehydration.
It takes only a tiny number of virus particles to cause infection, the virus is hardy on surfaces, and it spreads easily person to person. This makes closed settings like aged care, childcare and food venues prone to rapid outbreaks.