Norovirus is back and hitting hard.
More than 80 people got sick after eating oysters at a Los Angeles County event in early December.
Passengers on back-to-back cruises on Cunard’s Queen Mary 2 got sick with norovirus. Among 2,565 guests, 326 reported being ill, along with 65 crew, the Centers for Disease Control and Prevention said.
According to the most recent numbers from the U.S. Centers for Disease Control, there were 91 outbreaks of norovirus reported during the week of Dec. 5. That’s almost double the number of outbreaks from prior years.
What is norovirus?
Norovirus is a very contagious virus that causes vomiting and diarrhea.
It is sometimes called the “stomach flu” or the “stomach bug.” However, norovirus illness is not related to the flu. Norovirus causes acute gastroenteritis, an inflammation of the stomach or intestines.
You can get norovirus illness many times in your life because there are many different types of noroviruses, the CDC said.
Are norovirus outbreaks common?
The CDC reported there are about 2,500 reported norovirus outbreaks in the United States every year.
Norovirus outbreaks occur throughout the year but are most common from November to April.
Norovirus is the leading cause of foodborne illness in the United States, the CDC said. It causes 58% of foodborne illnesses acquired in America.
How does norovirus spread?
Norovirus spreads very easily and quickly in different ways, the CDC said. You can get norovirus by:
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Having direct contact with someone with norovirus.
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Eating food or drinking liquids that are contaminated with norovirus.
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Touching contaminated objects or surfaces and then putting your unwashed fingers in your mouth.
You can spread norovirus for two weeks or more after you feel better.
Most norovirus outbreaks happen when infected people spread the virus to others through direct contact, the CDC said.
What is a ‘norovirus outbreak’?
A norovirus outbreak occurs when there is an “occurrence of two or more similar illnesses resulting from a common exposure that is either suspected or laboratory-confirmed to be caused by norovirus,” according to the CDC.
The NoroSTAT network — which lists norovirus outbreaks from state health departments — includes Alabama, Colorado, Massachusetts, Michigan, Minnesota, Nebraska, New Mexico, North Carolina, Ohio, Oregon, South Carolina, Tennessee, Virginia, and Wisconsin.
Florida is not included on the list.
State, local, and territorial health departments are not required to report individual cases of norovirus illness to CDC.
The most recent data available shows 24 outbreaks of norovirus in Florida between Sept. 1, 2023, and Oct. 31, 2024, based on data sent to CDC’s CaliciNet.
Symptoms of norovirus, or stomach bug
A person usually develops symptoms 12 to 48 hours after being exposed to norovirus.
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Most common symptoms: Diarrhea, vomiting, nausea, stomach pain
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Other symptoms: Fever, headache, and body aches
Norovirus is the leading cause of vomiting and diarrhea, and foodborne illness in the United States, according to the CDC.
Most people with norovirus illness get better within one to three days, can can still spread the virus for a few days after.
Are outbreaks of norovirus on cruise ships increasing?
The CDC has logged 16 outbreaks of gastrointestinal illness on cruises that met its threshold for public notification in 2024. In 13 of those, norovirus was listed as the causative agent. The others were caused by E. coli, salmonella, or listed as unknown.
Norovirus outbreaks do tend to take place in congregate settings, particularly where people consume food and beverages, Dr. Dean Winslow, a professor of medicine and pediatrics at Stanford Medicine, told USA TODAY.
He noted a cruise ship is a “closed environment” where people cannot as easily distance themselves from others.
“I look at a cruise ship as really kind of a perfect storm for a number of environmental factors,” Winslow said.
Eating raw shellfish could put you at risk for norovirus. See recalls
Anyone who consumes raw shellfish is at risk of contracting norovirus, the CDC said.
Cook oysters and other shellfish thoroughly to an internal temperature of at least 145 degrees.
The United States Food and Drug Administration issued multiple advisories in December for oysters and clams it said could be contaminated with norovirus.
The recalled oysters came from British Columbia, Canada, with a recall first being issued in California.
Another recall was also issued by the FDA on oysters from Washington state and Manila clams. The administration said these recalled seafood products could be contaminated with the norovirus.
How to prevent spread of norovirus, stomach flu
The key to fighting norovirus is by making sure everything stays nice and clean
The CDC offered several suggestions to help prevent the spread of norovirus:
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Wash your hands often with soap and water for at least 20 seconds, especially:
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After using the toilet or changing diapers.
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Before eating, preparing, or handling food.
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Before giving yourself or someone else medicine
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Immediately remove and wash clothes or linens that may have vomit or poop on them.
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Wear rubber or disposable gloves.
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Handle items carefully without shaking them.
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Wash the items with detergent and hot water at the maximum available cycle length and then machine dry them at the highest heat setting.
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Wash your hands after with soap and water.
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Be aware noroviruses are relatively resistant to heat and can survive temperatures as high as 145 degrees.
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Carefully wash fruits and vegetables well.
Will hand sanitizer help prevent norovirus?
Don’t count on hand sanitizer to prevent norovirus, the CDC said.
“Hand sanitizer does not work well against norovirus.
“You can use hand sanitizers in addition to hand washing, but hand sanitizer is not a substitute for handwashing, which is best.”
Contributing: Nathan Diller, USA Today Network
This article originally appeared on Florida Times-Union: Stomach flu highly contagious norovirus. Symptoms, prevention
