• Infectious Diseases A-Z: Stomach bug or seasonal flu?

a word definition for norovirus with medicine pills on the paperNorovirus or influenza? Both are highly contagious viral infections, but they are not the same. Mayo Clinic infectious diseases specialist Dr. Pritish Tosh says people often mean norovirus when they refer to a stomach bug but confuse it with the flu. Influenza affects your respiratory system — nose, throat and lungs — and symptoms often include fever, chills and sore throat, along with a dry persistent cough.

"Norovirus is a virus that causes viral gastroenteritis, meaning an infection of the gastrointestinal system," says Dr. Tosh. "People often will get diarrhea and vomiting. Often, it lasts just a day or so, and people get better. They need to maintain good fluids intake and plenty of rest."

Watch: Dr. Tosh explains norovirus.

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"Most people who get norovirus get better on their own within a day or two," says Dr. Tosh. "Now, it’s a pretty uncomfortable day or two, and it’s important that people maintain good fluid intake. Plain water is often enough, but if that fluid loss is more, maintaining a good electrolyte balance is also going to be important." He adds that dehydration can be an issue due to diarrhea, so consuming a sports drink containing electrolytes may also help.

Dr. Tosh says norovirus is highly contagious. He advises people to use good hand hygiene to avoid contact with the virus, especially when handling food.