The Centers for Disease Control and Prevention (CDC) estimates that 23 million cases of acute gastroenteritis are due to norovirus infection, and it is now thought that at least 50 percent of all foodborne outbreaks of gastroenteritis can be attributed to noroviruses.
Among the 232 outbreaks of norovirus gastroenteritis reported to the CDC from July 1997 to June 2000:
- 57 percent were foodborne
- 16 percent were due to person-to-person contact
- 3 percent were waterborne.
In 23 percent of the outbreaks, the cause of norovirus transmission was not determined.
In this study, common settings for norovirus gastroenteritis outbreaks included:
- Restaurants and catered meals (36 percent)
- Nursing homes (23 percent)
- Schools (13 percent)
- Vacation settings or cruise ships (10 percent).
(Click Norovirus Statistics for more information.)
Norovirus gastroenteritis is referred to by several different names, including:
- Stomach flu. This "stomach flu" is not related to the flu (or influenza), which is a respiratory illness caused by influenza virus.
- Viral gastroenteritis. The most common name for illness caused by norovirus. "Gastroenteritis" refers to an inflammation of the stomach and intestines.
- Acute gastroenteritis.
- Non-bacterial gastroenteritis.
- Food poisoning (although there are other causes of food poisoning).
- Calicivirus infection.