Norovirus infection - including symptoms, treatment and prevention

Norovirus infection is a type of viral gastroenteritis (also known as ‘gastro’: inflammation of the stomach and intestines (bowels)). Noroviruses (previously known as Norwalk-like viruses) are small round structured viruses that are members of a group of viruses called caliciviruses.

How norovirus is spread

Noroviruses are very infectious and can spread easily from person-to-person. Both faeces and vomit are infectious. People can become infected with the virus in several ways, including:

  • eating food or drinking liquids that are contaminated with norovirus by food handlers who have not washed their hands adequately or from environmental contamination
  • touching surfaces or objects contaminated with norovirus and then placing their hands in their mouth, or eating before washing their hands
  • having direct contact with another person who is infected, for example, when caring for someone with illness, or sharing foods or eating utensils with someone who is ill.

Signs And Symptoms

Norovirus infection causes gastroenteritis. Noroviruses are a very common cause of gastroenteritis outbreaks in South Australia.

Illness often begins suddenly and symptoms usually last 1 or 2 days. However, during that brief period people can feel very ill and vomit, often violently and without warning, many times a day.

Common symptoms include:

  • nausea
  • vomiting
  • diarrhoea
  • abdominal cramps.

Other symptoms may include:

  • headache
  • low grade fever
  • chills
  • muscle aches
  • general sense of tiredness.

Diagnosis of norovirus infection

Diagnosis can be made by PCR (polymerase chain reaction) testing of a faecal sample in a pathology laboratory, but is usually only done for investigation of outbreaks.

Incubation period

(time between becoming infected and developing symptoms)

Symptoms usually begin 24 to 48 hours after ingestion of the virus, but can appear as early as 12 hours after exposure.

Infectious period

(time during which an infected person can infect others)

Norovirus can be found in the faeces and vomit of infected people from the day they start to feel ill and up to 2 weeks after they recover.

Treatment for norovirus infection

No specific therapy exists for norovirus infection and there is no vaccine available.

The following are general recommendations for the treatment of gastroenteritis:

  • Give plenty of fluids. Oral rehydration solution is highly recommended for children with mild to moderate dehydration. It is available at pharmacies and should be administered following the instructions on the packaging.
  • Mildly unwell children should be given their usual fluids more often Carbonated (fizzy) drinks or undiluted juice should be avoided.
  • Medicines to prevent vomiting or diarrhoea should not be given (especially in children), except where specifically advised by a doctor.
  • Breastfed babies should continue to be breastfed throughout their illness.
  • Children on formula or solid diets should restart their normal diet (including full strength lactose containing milk) following rehydration with oral rehydration solution.
  • Children who are hungry or ask for food should be given small portions of their usual foods, but avoid foods high in sugar or fat.

When to seek medical attention

Seek medical advice if there are any of the following symptoms:

Adults

  • Signs of dehydration, such as thirst and decreased urination, lethargy, dry mouth, feeling faint on standing
  • fever
  • severe abdominal pain
  • bloody diarrhoea.

Children

  • Signs of dehydration, such as thirst and decreased urination, lethargy, dry mouth, sunken eyes, feeling faint on standing
  • fever
  • abdominal pain
  • bloody diarrhoea
  • any symptoms in a child less than 12 months of age.

Prevention of norovirus infection

  • Exclude people with norovirus infection from childcare, preschool, school and work until there has been no vomiting or diarrhoea for 24 hours. If working as a food handler in a food business, the exclusion period should be until there has been no diarrhoea or vomiting for 48 hours.
  • Infants, children and adults with norovirus infection should not swim until there has been no diarrhoea for 24 hours.
  • 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 infectious and can spread rapidly throughout such environments.
  • Wash hands after using the bathroom and changing nappies.
  • Wash hands before eating or preparing food for yourself or others.
  • Good food handling procedures should always be followed.
  • Immediately remove and wash clothing or bedding that may be contaminated with virus after an episode of vomiting or diarrhoea. Clean using hot water and soap.
  • After an episode of vomiting or diarrhoea, thoroughly clean contaminated surfaces with detergent and water and then disinfect contaminated surfaces immediately by using a household bleach diluted according to the manufacturer’s instructions.
  • Flush or discard any vomit and/or faeces in the toilet and make sure the surrounding area is kept clean.
  • Babies and small children without diarrhoea who are not toilet trained should wear tight fitting waterproof pants or swimming nappies in swimming pools and changed regularly in the change room. When faecal accidents occur, swimming pools should be properly disinfected.

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