Cases of norovirus, also known as the stomach flu, are rising across the country.
Specifically, in the northeastern U.S., positivity rates have hit 13.4% as of Feb. 17, as reported by the U.S. Centers for Disease Control and Prevention (CDC).
Norovirus is very contagious, according to the CDC. It can cause diarrhea, vomiting, nausea and stomach pain.
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The stomach bug can be spread through contaminated food or water, as well as through contact with sick people and contaminated surfaces.
Fox News medical contributor Dr. Marc Siegel addressed the uptick in cases during a Monday appearance on "Fox & Friends."
The NYU Langone physician said that while washing your hands is an effective prevention strategy, norovirus can still spread through food.
"It gets in food, it gets in waste," he said.
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"People are touching each other’s hands, food handlers spread it. It’s spread indoors because everybody’s indoors [during] the winter."
Siegel said he asked Mandy Cohen, the CDC's director, on Sunday if the agency plans to test wastewater to examine virus spread, and her answer was "no."
"That surprised me because we’re starting to use wastewater analysis everywhere," he said.
"I think that that’s probably a good idea."
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The "biggest problem" with norovirus, according to Siegel, is that it causes dehydration due to symptoms like vomiting and diarrhea.
"The elderly end up in the hospital – 100,000 of them a year," he said.
"It’s the most common kind of stomach flu we have [and] this is the season for it."
He added, "If you have these symptoms, it’s norovirus."
To ensure proper hydration, Siegel recommended taking "something with electrolytes," such as Gatorade or Pedialyte.
"Drink plenty of it," he said. "That’s the key to the treatment. [There's] no vaccine, no pill for it."
There is no medication available to treat people with norovirus illness, the CDC stated on its website.
