Noroviruses are a group of related viruses that cause vomiting and diarrhoea in humans and are a cause of travellers’ diarrhoea.
This infection is also commonly called, winter vomiting disease, summer vomiting disease, Norwalk virus disease or epidemic viral gastroenteritis. It occurs worldwide and affects all age groups.
Noroviruses are spread by direct person to person contact or by consuming faecally contaminated food and water. Environmental contamination can also act as a source of infection e.g. by touching door handles, crockery and cutlery.
Noroviruses are highly infectious. Those infected shed billions of virus particles in their vomit and stool and few particles are needed to cause infection. Shedding of viruses may continue after symptoms have resolved, usually for 48-72 hours but it may be longer.
Norovirus infections can very quickly spread through closed communities such as nursing homes, hospital wards, children's nurseries and on cruise ships.
The incubation period in humans is usually between 12-48 hours. Symptoms have a rapid onset and include projectile vomiting, watery non-bloody diarrhoea, abdominal cramps, nausea and sometimes a mild fever. Vomiting is more common in children. Symptoms last for 2-3 days and then resolve.
The most common complication is dehydration. Infants, the elderly and those with other health problems are most at risk and may require medical attention.
Treatment consists of relieving the symptoms and replacing the fluids lost by vomiting and diarrhoea. This can be done by drinking fluids or rehydration solution or in severe cases in hospital by intravenous infusion.
Antibiotics have no effect on this illness as it is caused by a virus.
There is no vaccine against norovirus infection.
Norovirus infection is a risk worldwide, and particularly during cruise travel.
The risk of norovirus infection can be reduced by practicing strict food and water hygiene and personal hygiene. All travellers should take precautions to ensure that all food and water consumed is safe.
- Hands should be washed with soap and water prior to handling food, eating and always after using the toilet.
- Shellfish should be thoroughly cooked before being eaten. Raw fruit and vegetables should be peeled prior to consumption.
- Contact with travellers with symptoms of norovirus should be limited to avoid infection.
- If caring for, or in contact with an individual with norovirus infection, careful handling of potentially infectious material is essential. This includes safe disposal of vomit/diarrhoea, soiled clothing, bedding, unfinished food, crockery and cutlery.
- All contaminated surfaces must be thoroughly cleaned and disinfected using a bleach based household cleaner.
Handwashing facilities may be poor or not available when travelling, therefore it is advisable to carry sanitising gel or hand wipes at all times.