What are norovirus infections?
Noroviruses are a group of viruses that cause an infection in the stomach and intestines called gastroenteritis. It is often called Norwalk-like virus, or the “stomach flu” though it is not caused by the influenza virus.
Norovirus infections have been linked to outbreaks of vomiting and/or diarrhea in day nurseries, schools, long term care homes, cruise ships, camps, dormitories, restaurants, households and other places where people gather in groups.
How do you get norovirus infection?
Noroviruses are found in the stool and sometimes in the vomit of ill persons.
Norovirus infections spread very easily and in several ways including:
- Having close contact with another person who is infected and has symptoms.
- Eating food or beverages that are contaminated with the virus. Food may become contaminated by food handlers who are ill with norovirus, especially if they do not wash their hands properly after using the washroom and before touching food. Food such as shell fish can also be contaminated at the source.
- Touching surfaces or objects contaminated with norovirus, and then placing contaminated fingers in the mouth (e.g., children may become ill if they touch contaminated toys and then put their fingers in their mouths).
Who is at risk of getting norovirus infection?
Anyone can get norovirus infection since it is highly contagious. Most people will recover with no complications. The symptoms of norovirus infection may be more severe for infants, young children, the elderly and those with weak immune systems.
What are the symptoms of norovirus infection?
Most individuals with norovirus infection will experience 1 to 3 days of:
- Nausea
- Vomiting
- Watery diarrhea
Other symptoms may include fever, headache, and stomach cramps. Severe illness or hospitalization is not common. Infected individuals usually recover within 2 to 3 days without serious or long-term health effects. Dehydration is the most common complication, especially among young children and the elderly.
If diarrhea is bloody, accompanied with a high fever or if the symptoms last longer than 72 hours contact your doctor. Your illness may be due to something other than norovirus.
How soon do the symptoms appear?
Symptoms usually appear in 1 to 2 days after exposure to the virus, but can appear as early as 10 hours after exposure.
When and for how long is a person able to spread norovirus?
A person who is ill with norovirus infection is able to spread the virus from the moment they start to feel ill up to 2 days after the diarrhea stops.
How can norovirus infection be prevented?
- Keep your hands clean. Wash hands often with soap and warm water after using the toilet, diapering and before preparing or eating food. If soap and water is not available, use an alcohol-based hand sanitizer with a minimum of 60% alcohol if hands are not visibly soiled. Thoroughly washing hands with soap and water is preferred to prevent the spread of norovirus.
- Do not prepare food for others if you have symptoms of vomiting or diarrhea.
- Thoroughly and frequently disinfect environmental surfaces and equipment with a chlorine bleach disinfectant, especially in areas that are touched often (e.g., telephones, door handles, gym equipment, bed side rails, etc.). A chlorine bleach solution of 1 part household bleach to 50 parts water can be made from 2 teaspoons of household bleach mixed with 2 cups of water.
- Anyone who is ill with diarrhea or vomiting should stay home from school, day nursery or work and should not return until being symptom-free for at least 48 hours. This is especially important for those who work with food, the elderly or at a hospital.
Is there a vaccine for norovirus?
No. There currently is no vaccine available in Canada to prevent norovirus infections.
How is norovirus infection diagnosed?
Doctors generally diagnose norovirus based on symptoms that resolve after 2-3 days. However, a stool sample may be suggested in certain circumstances.
Can norovirus infection be treated?
There is no specific treatment for norovirus infection. Antibiotics are not useful because the illness is caused by viruses, not bacteria. Ill persons should drink plenty of fluids since dehydration is a common complication from norovirus infection.
Is norovirus infection the same as the “flu”?
People often refer to the symptoms of norovirus infection as the “stomach flu”. However, influenza (the flu) is a respiratory illness with symptoms of cough, sore throat and fever. While receiving the annual influenza vaccine is important each winter and is free for anyone who works, attends school or lives in Ontario, the influenza vaccine will not protect you against a norovirus infection.
