What is norovirus and is it dangerous?

Norovirus is a highly contagious virus that causes inflammation of the stomach and intestines, leading to vomiting and diarrhea. While most people recover within 1-3 days, it can be dangerous for young children, elderly individuals, and people with weakened immune systems due to severe dehydration. It's the leading cause of foodborne illness outbreaks worldwide.

How does norovirus spread so easily?

Norovirus spreads extremely easily through contaminated food or water, direct contact with infected people, or touching contaminated surfaces. It only takes a tiny amount (less than 100 viral particles) to cause infection. The virus can survive on surfaces for days and is resistant to many common disinfectants, making it particularly difficult to control.

What are the symptoms of norovirus?

Symptoms typically begin 12-48 hours after exposure and include sudden onset of nausea, vomiting, watery diarrhea, stomach cramps, and sometimes fever, headache, and body aches. The illness usually lasts 1-3 days, but you can still be contagious for up to 2 weeks after recovering.

Why doesn't hand sanitizer work against norovirus?

Alcohol-based hand sanitizers are less effective against norovirus compared to other viruses. The virus has no outer lipid envelope that alcohol can break down. The CDC recommends washing hands thoroughly with soap and water for at least 20 seconds, which physically removes the virus from your hands.

How can I clean up after someone with norovirus?

Use bleach-based cleaners (1000-5000 ppm chlorine) to disinfect surfaces. Clean up vomit and feces immediately, wearing gloves and a mask if possible. Wash contaminated laundry in hot water. The virus can survive on surfaces for days, so thorough cleaning is essential to prevent spread.

Where are norovirus outbreaks happening?

Norovirus outbreaks are common in closed or semi-closed environments like cruise ships, nursing homes, schools, and restaurants. Outbreaks peak during winter months but can occur year-round. Check the live outbreak data above for current norovirus activity in your area.

Norovirus

1 Active Outbreak

Norovirus is a highly contagious virus that causes acute gastroenteritis, inflammation of the stomach and intestines. Often called the 'stomach flu' or 'winter vomiting bug,' it is the leading cause of foodborne illness outbreaks worldwide.

Countries Affected

497

Recent Cases (30d)

Active Outbreaks

13d ago

Last Updated

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What is Norovirus?

Norovirus is the leading cause of vomiting and diarrhea from acute gastroenteritis in the United States and globally. It causes approximately 21 million illnesses, 70,000 hospitalizations, and 800 deaths annually in the U.S. alone. The virus is extremely contagious - just a few viral particles can cause infection, and infected people can shed billions of virus particles.

Symptoms

Sudden onset of nausea and vomiting
Watery diarrhea
Stomach cramps and abdominal pain
Low-grade fever
Body aches and headache
Fatigue and weakness

Transmission

Norovirus spreads through contaminated food or water, contact with contaminated surfaces, and direct person-to-person contact. The virus is extremely contagious and only a few viral particles are needed to cause infection. Outbreaks are common in closed environments like cruise ships, schools, and nursing homes.

Contagious Period: From symptom onset through at least 3 days after recovery (virus can be shed up to 2 weeks)

Prevention

Thorough handwashing with soap and water (alcohol sanitizers less effective)
Wash fruits and vegetables before eating
Cook shellfish thoroughly
Clean and disinfect contaminated surfaces with bleach-based cleaners
Stay home when sick and for 48 hours after symptoms resolve
Avoid preparing food for others when ill
Wash laundry thoroughly if contaminated

Active Outbreaks & Recent Cases

Real-time intelligence from global health monitoring and AI-powered surveillance

Data sources: BEACON, ProMED, WHO, CDC, and 50+ national health agencies

✓ Live data updated in real-time from global health sources

Japan Norovirus Cases Surge Fifth Week in a Row

Japan 2026-02-19

Active

Japan has seen an increase in gastroenteritis outbreaks in 2025, primarily caused by norovirus, reaching the highest level in 10 years.

Source: BEACON - View Full Report

497 0

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Expert Resources & References

Trusted information from leading health organizations

CDC

Official guidance from the U.S. Centers for Disease Control and Prevention

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WHO

Global disease surveillance and guidelines from the World Health Organization

View WHO Resources →

Research

Latest peer-reviewed research and clinical studies

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Medically Reviewed Content

Disease information on Virus Watcher is reviewed by our Chief Epidemiologist, a former CDC lead analyst for FluSight forecasting. Outbreak data is aggregated from verified sources including BEACON, ProMED, WHO, CDC, and 50+ national health agencies. This information is for educational purposes and should not replace professional medical advice.

Last reviewed: 2026-03-05

Frequently Asked Questions

Common questions about Norovirus answered by our epidemiology team

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