Norovirus infection

3D graphical representation of a single Norovirus virion. Credit: CDC/ Jessica A. Allen

Norovirus is a highly contagious virus. Most people recover from norovirus illness within one or two days. The time between getting infected and showing symptoms typically falls between 12 to 48 hours. 

The symptoms of norovirus infection are:

  • vomiting
  • diarrhoea
  • stomach pain 

Some less common symptoms include: 

  • low-grade fever 
  • chills
  • headache

While it is uncommon, dehydration due to prolonged diarrhoea may lead to  death, particularly in the elderly or individuals with weakened immune systems.

Key facts

Risk for people 

Norovirus infections can spread rapidly among people, especially in community settings such as hospitals, schools, daycare centres, and nursing homes. These places often see outbreaks due to close contact among individuals.

Noroviruses are part of the Caliciviridae family and are known for causing what is often called "winter-vomiting disease" or "stomach flu" which often spreads during the winter months. The viruses can withstand freezing and high temperatures (up to 60°C), and can also persist on surfaces for extended periods. 

How it spreads  

Noroviruses are highly contagious, and it takes only a small number, typically between 10 to 100 viral particles, to infect someone. 

These viruses are primarily spread through what is known as the "faecal-oral route," which means they can be transmitted when areas contaminated with the virus come into contact with the mouth. This can happen through consuming contaminated food or water, or through direct person-to-person contact.

Vomiting can be particularly concerning, as it can release aerosols that contain a high concentration of virus particles. These aerosols can then enter a person's mouth or contaminate surfaces, contributing to the virus's spread. 

During a norovirus outbreak, multiple modes of transmission often occur. 

Immunity to noroviruses is relatively short-lived, lasting only a few months, and it is specific to the particular strain of the virus that an individual is exposed to. Given the genetic diversity of noroviruses, people can be infected multiple times throughout their lives. Some individuals however appears to be resistant to infection and disease from the most common form of norovirus, due to genetic factors.

Protective measures  

To help prevent the spread of illness, it is important to follow these simple steps:

  • handwashing with soap and water: ensure proper hand hygiene after using the bathroom or toilet and, notably, before preparing food
  • isolating, in cases of illness: individuals are advised to isolate the sick person as much as possible to minimise the potential spread of the illness to others
  • cleaning and disinfecting public areas, especially restrooms where vomiting has occurred. Use disinfectants that are effective against viruses.
  • when cleaning up vomit, it is advisable to use disposable gloves. If you use rubber gloves, make sure to disinfect them before removing them from your hands. Use of surgical  masks may offer some protection against inhaling airborne particles.
  • if someone experiences gastrointestinal symptoms, they should refrain from handling food and avoid food preparation areas for at least 48 hours after their symptoms have resolved.

Read more

Latest outputs