Norovirus Worldwide

Global Trends

Worldwide, about one out of every five cases of acute gastroenteritis (inflammation of the stomach or intestines) that leads to diarrhea and vomiting is caused by norovirus. Norovirus is the most common cause of acute gastroenteritis, annually causing an estimated 685 million cases. About 200 million cases are seen among children under 5 years old, leading to an estimated 50,000 child deaths every year, mostly in developing countries. However, norovirus illness is a problem in both low- and high-income countries. Every year, norovirus is estimated to cost $60 billion worldwide due to healthcare costs and lost productivity.

Norovirus illnesses and outbreaks are usually more common in cooler winter months. The majority of all outbreaks occur from November to April in countries above the equator, and from May to September in countries below the equator. However, in places closer to the equator, norovirus may be less seasonal.


Globally, norovirus is the leading cause of acute gastroenteritis outbreaks. Since 2002, GII.4 viruses (genogroup II genotype 4) have caused the majority of norovirus outbreaks worldwide. Although in recent years, non-GII.4 viruses, such as GII.17 and GII.2, have temporarily replaced GII.4 viruses in several Asian countries. Between 2002 and 2012, new GII.4 viruses emerged about every 2 to 4 years, but since 2012, the same virus (GII.4 Sydney) has been the dominant strain worldwide. Often, but not always, these new strains lead to a global increase in norovirus outbreaks.

CDC works with many global partners to identify the burden of acute gastroenteritis caused by norovirus and to prevent norovirus outbreaks.


Global Burden of Norovirus report cover
see caption for description

Electron microscopic image of norovirus virions

Infographic: Foodborne Diseases Are Preventable. Everyone Has a Role to Play.

The WHO Foodborne Disease Burden Epidemiology Reference Group (FERG) recently issued a comprehensive report estimating the global burden of foodborne diseases. Norovirus ranks as

  • #1 cause of foodborne illness
  • #4 cause of foodborne deaths
  • #5 cause of foodborne DALYs (disability-adjusted life years)