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.

Outbreaks

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.

Resources

• Estimates of the Global Burden of Foodborne Diseases
  This PLOS collection reports the first estimates of the incidence, mortality, and disease burden caused by 31 foodborne hazards
• The Global Burden of Norovirus & Prospects for Vaccine Development
  This PLOS norovirus collection fills critical knowledge gaps and provides key information for the development of a much-needed vaccine. This is a “living collection” and more articles will be added over time.

• Global Burden of Norovirus and Prospects for Vaccine Development [4.39 MB, 46 pages]
  This report describes the work of norovirus researchers from around the world on the global burden of norovirus, and outlines further research needed to fill gaps in knowledge in order to make norovirus vaccines a reality.