Cases of norovirus, a highly contagious virus that causes gastrointestinal illness, are rising across the United States as the winter illness season begins.
According to data from the US Centers for Disease Control and Prevention (CDC), infections typically increase during the colder months when people spend more time indoors, creating more opportunities for the virus to spread.
Common symptoms
Doctors say norovirus most often causes:
- nausea
- vomiting
- diarrhoea
- stomach cramps
- fever in some cases
Most people recover within one to three days without medical treatment, although symptoms can sometimes last longer.
Health experts advise paying close attention to signs of dehydration, particularly among children and older adults.
When to seek medical help
While most cases can be managed at home, medical attention may be needed if symptoms become severe.
Doctors warn that persistent dehydration, dizziness, high fever or blood in the stool could indicate a more serious condition requiring assessment by a healthcare professional.
In some cases, severe dehydration may require treatment with intravenous fluids.
Why norovirus spreads so easily
Norovirus is considered one of the most contagious viruses affecting humans.
Experts say it can survive on surfaces for extended periods and spreads rapidly in places where people gather closely together, including:
- schools
- nursing homes
- hospitals
- cruise ships
Outbreaks have also been linked to contaminated food, particularly raw oysters.
Research has suggested that the virus survives more effectively in cooler temperatures, contributing to seasonal increases during autumn and winter.
Handwashing remains the best protection
Health specialists stress that proper handwashing with soap and water remains the most effective way to reduce the risk of infection.
Unlike many respiratory viruses, norovirus is not easily eliminated by alcohol-based hand sanitisers.
People are advised to wash their hands thoroughly:
- before eating
- after using the toilet
- after changing nappies
- after caring for someone who is ill
Stay home if you become ill
Doctors recommend staying away from work, school and social gatherings while experiencing vomiting or diarrhoea.
People recovering from norovirus are also encouraged to avoid preparing food for others for at least two to three days after symptoms have resolved, helping prevent further spread.
Experts note that a relatively new strain of norovirus has been circulating during 2026, raising concerns that this winter's season could prove more active than usual.
