Norovirus (Stomach Flu) Outbreaks Increasing in U.S. - Everyday Health

The highly contagious norovirus is causing outbreaks of stomach flu around the country, according to the latest report from the Centers of Disease Control and Prevention (CDC).

CDC surveillance data reported 225 norovirus outbreaks from August 2022 to January 2023, about 30 percent higher than the 172 outbreaks reported during the same period the year before.

An "outbreak" isn't a specific number of people; instead, it's defined as a higher than normally expected number of cases occurring in a community, geographical area, or season, according to the World Health Organization (WHO). For example, if a cluster of children in the same class are all absent from school due to a gastrointestinal illness and it turns out they all have the same infectious disease, that's an outbreak.

In a typical year, norovirus causes between 19 and 21 million cases of vomiting and diarrhea illnesses, 109,000 hospitalizations, and 900 deaths in the United States.

This Year's Norovirus Season Back to Pre-COVID Levels

Despite the current rise of norovirus cases, the number of outbreaks so far this year is within the range reported during the same periods from 2012 to 2020. As with other infectious diseases, such as the flu, cases of norovirus were lower than usual during the pandemic, and now they're back to their pre-COVID levels, says Amesh Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security in Baltimore.

This year is following the typical pattern, he says. "Norovirus traditionally has a season from November to April, and we are in the midst of it now," says Dr. Adalja.

'Winter Vomiting Disease' Is Upon Us

This is the time of year that we expect to see a substantial rise in norovirus infection, agrees Paul Pottinger, MD, professor in the division of allergy and infectious diseases at UW Medicine in Seattle.

"In fact, in the old days, it was called 'winter vomiting disease.' The seasonal increase in transmission probably relates to crowding of people together inside, where we are more likely to come into contact with each other, and with objects we have touched," says Dr. Pottinger.

On top of that, the germ that causes norovirus is notoriously hardy and is not reliably inactivated by hand sanitizer. That's why it's so easily transmitted when people are crowded together, such as on cruise ships, he adds.

Norovirus Can Spread Via Contaminated Food or Water and From Person to Person

"Anyone can catch this virus. It is highly contagious," says Adalja. Infection occurs when you accidentally get tiny particles of feces or vomit from an infected person in your mouth, according to the CDC.

People who are infected shed billions of microscopic norovirus particles and it only takes a few to make other people sick. That's why washing your hands frequently — especially after a trip to the bathroom — is key in the prevention of norovirus, says Pottinger.

The virus most often spreads via food or water that is contaminated with norovirus or by touching contaminated surfaces or objects and then putting your fingers in your mouth.

In the United States, norovirus is the number one cause of illness and outbreaks from contaminated food, and most often occurs in restaurants, grocery stores with food bars, or other grab-and-go settings.

One way the virus can spread is if a person with norovirus touches food with bare hands that have feces or vomit particles on them. Food placed on a counter or surface that has feces or vomit particles can carry the norovirus, as can vegetables and fruit watered or harvested with contaminated water.

It's also transmissible from person to person through sharing food or eating utensils, or caring for and cleaning up after a person with norovirus. People with the virus are most contagious when they have symptoms — especially vomiting — and during the first few days of recovery. However, people can spread norovirus for up to two weeks after their symptoms have ended.

Can Norovirus Cause Hospitalization or Death?

Although norovirus can make even the healthiest person feel horrible, the infection and its symptoms usually go away within a few days. But complications can occur, and they are more common in the elderly and those prone to dehydration, says Adalja.

In severe cases, norovirus can cause serious dehydration and even death, according to Mayo Clinic.

How Do You Know if GI Symptoms Are Due to Norovirus, Food Poisoning, or Even COVID-19?

Figuring out if you have food poisoning or norovirus is difficult, partly because "food poisoning" is not a very scientific term but used informally, says Adalja.

"Certain types of foodborne illnesses may occur immediately after eating — for example, S.aureus toxin exposure — while norovirus has an incubation period of about a day. But for all intents and purposes, it is very difficult to distinguish any of these illnesses apart from each other, except for the prominence of vomiting with norovirus," he says.

Another difference is that food poisoning typically resolves after about a day, whereas norovirus symptoms can easily last up to five days and even longer in some cases, especially if people have reduced immune function, says Pottinger.

People infected by norovirus should not mistake it for COVID-19, either, says Pottinger. "COVID can have G.I. manifestations, but they should not be nearly as violent, severe, and debilitating as the vomiting, abdominal pain, and diarrhea we see with norovirus."

Diagnosing and Treating Norovirus

Right now, there's no home test available for norovirus, says Pottinger. "Healthcare providers may choose to test patients if they have a reduced immune system, or if they fail to improve with supportive care, or remain sick beyond the expected duration of illness," he says.

In general, however, norovirus is a clinical diagnosis that doctors make after talking to and examining a patient, he says.

There is no antiviral treatment for norovirus that is approved by the U.S. Food and Drug Administration, says Pottinger. Antibiotics will not help because they fight bacterial infections, not viruses.

If you have norovirus, staying hydrated is key. Drink plenty of liquids to replace lost fluids and watch out for signs of dehydration, per the CDC.

Tips for Reducing Your Risk of Catching Norovirus

The CDC lists these tips for preventing norovirus:

• Wash your hands frequently with soap and warm water, especially after using the bathroom, changing diapers, giving or taking medicine, or before eating or preparing food.
• You can use alcohol-based hand sanitizers in addition to hand washing, but it shouldn't be a substitute — hand sanitizers don't work well against norovirus.
• Avoid preparing food for others if you are experiencing symptoms of norovirus.
• Cook shellfish and other foods thoroughly before eating.
• Clean and disinfect surfaces and objects that may be contaminated with norovirus, such as countertops, doorknobs, and toilets.
• Clothes and linens that may be soiled with vomit or feces should be handled with disposable or rubber gloves, washed with detergent and hot water and dried at the highest dryer setting.
• Stay home if you are sick and avoid close contact with others, particularly in settings where norovirus can easily spread, such as schools and nursing homes.

Adblock test (Why?)