Stomach flu: How long am I contagious?

You can pass stomach flu, also known as gastroenteritis, to others from a few days up to two weeks or more. The time depends on which virus is causing your illness.

Although it's commonly called stomach flu, gastroenteritis isn't the same as influenza, also known as flu. The flu affects the respiratory system — the nose, throat and lungs. Gastroenteritis, on the other hand, is an infection of the intestines.

Noroviruses, rotaviruses and other viruses can cause gastroenteritis. These viruses spread between people who are in close contact. They are spread through contact with the stool or vomit from a sick person.

The contagious period is the time when a person can give the illness to others. This period differs slightly for each virus.

• Norovirus. Norovirus is the most common cause of viral gastroenteritis. With norovirus, you can be contagious before you feel ill. Symptoms usually appear within 1 to 2 days being exposed to the virus.

  Most people with norovirus feel better a day or two after their symptoms begin. But they're contagious for a few days after they recover. The virus can stay in the stool for two weeks or more after recovery.

  Children should stay home from school or child care for at least two days after the last time they vomit or have diarrhea.

• Rotavirus. Rotavirus as a cause of viral gastroenteritis is more common in infants and young children. Symptoms of rotavirus usually appear 1 to 3 days after a person is in contact with the virus and last 3 to 8 days.

  But people with rotavirus are contagious even before they develop symptoms. They're still contagious up to two weeks after they've recovered.

Washing your hands often with soap and water is the best way to stop the spread of these viruses to others. Hand-washing works much better than alcohol-based hand sanitizer for norovirus.

To help keep others from getting sick, disinfect contaminated surfaces right after someone vomits or has diarrhea. Wear gloves that you can throw out after using them, called disposable.

Use a bleach-based household cleanser. You can make your own with 5 to 24 tablespoons (74 to 355 milliliters) of bleach in 1 gallon (3.8 liters) of water. Norovirus can survive for months on surfaces not disinfected well enough with bleach solution.

Also wear disposable gloves to wash clothes or linens right away if they might be contaminated.

To prevent the spread of rotavirus, infants can get a rotavirus vaccine.

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