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A viral disease
What is it?
Photo of NorovirusPhoto credit: CDC/ E. L. Palmer

Noroviruses are a group of similar microscopic organisms that cause intestinal disease in humans. Notorious for outbreaks on cruise ships, noroviruses are by far the most common cause of digestive disease on the planet. Noroviruses are extremely contagious—fewer than 10 virus particles may be enough to make you sick.

How do I avoid it?

Noroviruses can be hard to kill, but they are fairly easy to avoid. The best ways to sidestep this most common illness are:

  • Wash your hands every time you use the toilet or change a diaper, and before eating or handling food.
  • Practice proper handling of food products.
  • Stay away from sick people, and encourage them to stay home to avoid spreading the disease. (A person can carry the virus for up to two weeks.)

What are the symptoms?

It usually takes 24-48 hours after swallowing the virus for symptoms to start. They include:

  • vomiting
  • watery, non-bloody diarrhea with abdominal cramps
  • nausea
  • low-grade fever
Children and the elderly may become dehydrated and require medical attention. Most sufferers recover completely within 24-60 hours without any long-term effects.

How do I get it?

Noroviruses spread through human poop—the diarrhea it causes can lead to tiny drops that contaminate:

  • Food, especially cold foods like salads, sandwiches and bakery goods that have not been properly handled
  • Water, including beaches, tubs, fountains and wells contaminated by sewage or by sick swimmers
  • Surfaces—viral particles may survive on surfaces and get transferred to your hands

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