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Understanding Norovirus: Causes, Symptoms, Prevention, and Treatmentab

Abhijit Bhattacharyya | MD, PhD, MBA

Medically reviewed by Abhijit Bhattacharyya | MD, PhD, MBA, Tufts University School of Medicine - Miami, Florida on November 4th, 2023.

Key Takeaways

  • This RNA virus requires only 10-100 viral particles to cause infection, making it extraordinarily contagious—infected surfaces can harbor live virus for weeks at room temperature.

  • Projectile vomiting occurs in 79% of cases and typically begins 12-48 hours after exposure, followed by watery diarrhea that can exceed 20 episodes per day.

  • Dehydration develops rapidly due to fluid losses of 200-400mL per vomiting episode and 200-300mL per diarrheal stool, particularly dangerous for children under 5 and adults over 65.

  • Alcohol-based sanitizers are ineffective against this non-enveloped virus—only soap and water for 20+ seconds or bleach solutions (1,000-5,000 ppm) destroy it reliably.

  • Infected individuals shed billions of viral particles and remain contagious for 2-8 weeks after symptom resolution, with peak contagiousness during the first 24-72 hours of illness.

Norovirus is a highly contagious virus that causes acute gastroenteritis, an illness characterized by diarrhea and vomiting. It is the most common cause of stomach flu worldwide and can affect people of all ages. The virus spreads easily through contaminated food, drink, surfaces, and close contact with infected individuals.

Causes and Risk Factors

Norovirus is typically spread through:

  • Consuming contaminated food or drink

  • Touching contaminated surfaces and then touching your mouth, nose, or eyes

  • Close contact with an infected person

The virus thrives in crowded settings like restaurants, daycare centers, and nursing homes. Young children, the elderly, and people with weakened immune systems are at a higher risk of infection and complications.

Symptoms and Duration

Norovirus symptoms usually appear 12 to 48 hours after exposure and can include:

  • Nausea and vomiting

  • Watery diarrhea

  • Stomach cramps

  • Low-grade fever

  • Headache and body aches

  • Fatigue

Symptoms typically last 1 to 3 days, but you can remain contagious for up to 2 weeks after recovery.

Understanding Norovirus: Causes, Symptoms, Prevention, and Treatmentab

Diagnosis and Treatment

Doctors usually diagnose norovirus based on symptoms, but a stool test can confirm the presence of the virus. There is no specific treatment for norovirus, as antibiotics are ineffective against viruses. The best course of action is to manage symptoms by:

  • Drinking plenty of fluids (such as Pedialyte and Gatorade Endurance Formula) to prevent dehydration

  • Getting ample rest

  • Eating soft, bland foods as tolerated

If you experience severe dehydration, seek medical attention, as intravenous (IV) fluids may be necessary.

Prevention Methods

To reduce your risk of contracting or spreading norovirus:

  1. Wash your hands thoroughly with soap and water for at least 20 seconds, especially after using the bathroom or changing diapers and before preparing or eating food.

  2. Clean and disinfect contaminated surfaces with a mixture of detergent and chlorine bleach.

  3. Wash raw fruits and vegetables thoroughly before consuming.

  4. Cook oysters and other shellfish before eating.

  5. Stay home from work or school if you are infected, and avoid preparing food for others.

By following these prevention methods and maintaining good hygiene practices, you can help minimize the spread of norovirus and protect yourself and others from this common illness.

Additional Resources

The Bottom Line

Recovery depends entirely on preventing dehydration through frequent small sips of oral rehydration solutions, as no antiviral medications exist for this self-limiting illness. Most people recover within 72 hours, but seek immediate care if you can't keep fluids down for 24 hours or show signs of severe dehydration. If you're unsure whether your symptoms require medical attention, Doctronic can help assess your situation quickly.

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