Norovirus is a highly contagious infection also known as Norwalk virus. It is a common cause of vomiting and diarrhea each winter and is often referred to as ‘winter vomiting disease’ or ‘stomach flu’ (although it is not caused by the influenza virus). Norovirus infections have been linked to outbreaks of vomiting and/or diarrhea in child-care centres, long-term care homes as well as on cruise ships, camps, schools, restaurants, households and other places where people gather.
Norovirus is found in the stool and sometimes in the vomit of ill persons. People can become infected with the virus in several ways:
Those infected with Norovirus can spread it once they feel ill and for up to two days after the symptoms (usually diarrhea) stop but people can carry the virus for up to two weeks longer.
Infected individuals usually experience sudden onset of nausea, vomiting and watery diarrhea that lasts about one to three days. Other symptoms may include fever and stomach cramps.
Severe illness or hospitalization is uncommon. Dehydration is the most common complication, especially among young children and the elderly. Seek medical attention or call TeleHealth Ontario (1-866-797-0000) if you have high fever, bloody diarrhea or illness lasting longer than 72 hours.
Infected individuals usually recover in two to three days without serious or long-term health effects.
Symptoms usually appear within 10 hours but can develop up to two days after exposure to the virus.
Doctors generally diagnose Norovirus infection based on symptoms including the sudden onset, the short duration (usually one to three days) and the quick resolution of the infection. However, a stool sample may be collected by your doctor in certain circumstances.
People sometimes call Norovirus infection the “stomach flu”. However, influenza (the flu) is a respiratory (lung) illness with symptoms of cough, sore throat and fever. Getting the influenza vaccine each fall/winter (it is free for anyone who works, attends school or lives in Ontario), while important for protection against the flu, will not protect you against Norovirus infection.
Most people will recover from a Norovirus infection with no complications. The symptoms of Norovirus infection may be more severe for infants, young children, the elderly and those with weak immune systems. Dehydration can be more serious for these individuals who should seek medical attention if this becomes severe.
There is no specific treatment for Norovirus infection. Antibiotics are not useful because the illness is caused by a virus, not a bacterium. Ill persons should drink plenty of fluids to prevent dehydration.
No. There currently is no vaccine available in Canada to prevent Norovirus infection.
Call Toronto Public Health at 416-338-7600 (TTY at 416-392-0658) or speak to your health care provider.