Noroviruses are a group of viruses that can cause gastroenteritis (inflammation of the stomach and intestines) with diarrhoea, stomach pain and vomiting. Common names used for gastroenteritis due to norovirus are 'gastric flu' or 'stomach flu', 'winter vomiting' and 'viral gastro'.
Noroviruses are found in the faeces or vomit of infected people. People can become infected with the virus in several ways, including:
- eating food or drinking liquids that are contaminated with norovirus
- touching surfaces or objects contaminated with norovirus, and then placing their hand in their mouth
- small airborne particles from projectile vomiting
- having direct contact with another person who is infected and showing symptoms (for example, when caring for someone with illness, or sharing foods or eating utensils with someone who is ill).
Anyone can become infected with these viruses. There are many different strains of norovirus, which makes it difficult for a person's body to develop long-lasting immunity. Therefore, norovirus illness can recur throughout a person's lifetime.
People working in day-care centres or nursing homes should pay special attention to children or residents who have norovirus illness. This virus is very contagious and can spread rapidly throughout such environments.
Symptoms of norovirus illness usually begin about 24 to 48 hours after ingestion of the virus, but they can appear as early as 12 hours after exposure.
The symptoms of norovirus illness usually include nausea, vomiting, diarrhoea, and some stomach cramping. Sometimes people also have a low-grade fever, chills, headache, muscle aches, and a general sense of tiredness. The illness often begins suddenly, and the infected person may feel very sick. The illness is usually brief, with symptoms lasting only about 1 or 2 days, but can last longer. In general, children experience more vomiting than adults.
Currently, there is no antiviral medication that works against norovirus and there is no vaccine to prevent infection. Norovirus infection cannot be treated with antibiotics. This is because antibiotics work to fight bacteria and not viruses.
Norovirus illness is usually brief in healthy individuals. When people are ill with vomiting and diarrhoea, they should rest and drink plenty of fluids to prevent dehydration. Dehydration is the most serious health effect that can result from norovirus infection, and it is a particular concern in young children, the elderly, and people with weakened immune systems.
Noroviruses are very contagious and can spread easily from person to person. Both faeces and vomit are infectious. Particular care should be taken with young children in nappies who may have diarrhoea.
People infected with norovirus are contagious from the moment they begin feeling ill. If your job involves handling food or beverages or you are a childcare or health care worker you must not return to work until 48 hours after recovery (ie. until 48 hours after you last vomited or 48 hours after your bowel motions return to normal), as this is generally regarded as the period when people are infectious. However the virus can be present in faeces at low levels for several weeks after recovery, so it is important for people to continue to use good handwashing and other hygienic practices.
People infected with norovirus should not prepare food while they have symptoms and for 48 hours after they recover from their illness. Food that may have been contaminated by an ill person should be disposed of properly.
You can decrease your chance of coming in contact with noroviruses by following these preventive steps:
- Frequently wash your hands, especially after toilet visits and changing nappies and before eating or preparing food.
- Carefully wash fruits and vegetables, and steam oysters before eating them.
- Flush or discard any vomitus or faeces in the toilet and make sure that the surrounding area is kept clean.
- Use a detergent and hot water to wipe down the area where vomit was present so that no evidence of vomit is visible.
- Thoroughly clean and disinfect contaminated surfaces immediately after an episode of illness by using a bleach-based household cleaner.
- Immediately remove and wash clothing or linens that may be contaminated with virus (use hot water and soap).
Anyone can become infected with these viruses. There are many different strains of norovirus, which makes it difficult for a person's body to develop long-lasting immunity. Therefore, norovirus illness can recur throughout a person's lifetime. In addition, because of differences in genetic factors, some people are more likely to become infected and develop more severe illness than others.
Norovirus disease is usually not serious, although people may feel very sick and vomit many times a day. Most people get better within 1 or 2 days, and they have no long-term health effects related to their illness. However, sometimes people are unable to drink enough liquids to replace the liquids they lost because of vomiting and diarrhoea. These persons can become dehydrated and may need special medical attention. This problem with dehydration is usually only seen among the very young, the elderly, and persons with weakened immune systems. There is no evidence to suggest that an infected person can become a long-term carrier of norovirus.
?For further information, please contact your local doctor, community health centre or nearest public health unit, or contact the Queensland Health information line 13HEALTH (13 432584).