Ready for Norovirus 2024? The stomach bug is on the rise again

The 2023-2024 norovirus season is well underway in the United States. Cases of the highly contagious stomach bug, which causes diarrhea and vomiting, are climbing steadily across the country.

Although it’s commonly called the “stomach flu,” norovirus is not actually related to the flu, which is caused by influenza viruses.

Norovirus is a leading cause of acute gastroenteritis, or an inflammation of the lining of the stomach and intestines, according to the U.S. Centers for Disease Control and Prevention. This results in intense bouts of vomiting, diarrhea, nausea and stomach cramps.

Symptoms usually begin 12 to 48 hours after exposure — these are often sudden and very unpleasant, but most people will recover on their own.

“This is the dreaded virus that leaves us in the bathroom for about a day or two, we’ve all been there,” NBC News medical contributor Dr. Tara Narula said on TODAY in a segment aired Feb. 27.

Norovorius is extremely contagious, and anyone can become infected. Every year in the U.S., it causes about 20 million cases of vomiting and diarrhea, 465,000 emergency room visits, 109,000 hospitalizations, and 900 deaths, per the CDC.

Although norovirus spreads year-round, cases and outbreaks are most common in the winter. Right now, cases are on the rise across country, and outbreaks are surging in the Northeast and Western regions of the U.S.

According to the latest data from laboratories across the country reporting to the CDC, the rate of norovirus tests coming back positive, averaged over three weeks, is over 12% as of Feb. 17 — up from 9% in mid-January.

Norovirus (CDC)

Outbreaks of norovirus are also on the rise. From Aug. 1, 2023, to Feb. 12, 2024, there were 759 norovirus outbreaks reported by the 15 states participating in the CDC’s NoroSTAT surveillance program. During the same period the last seasonal year, there were 521 norovirus outbreaks reported.

“Currently, norovirus outbreak activity in the United States is within the range we would expect for this time of year and is within the range reported during the same time periods in previous years,” a spokesperson for CDC tells TODAY.com.

“We generally see an increase during winter and are continuing to monitor this,” the CDC spokesperson added.

Where is norovirus spreading?

Outbreaks of norovirus are impacting communities nationwide, but certain regions of the country are getting hit harder than others.

In the Northeast, norovirus is circulating at its highest rate since last April, NBC News previously reported. The percent of tests coming back positive in the Northeast region, averaged over three weeks, was more than 13% as of Feb. 17, per the latest CDC data.

Cities such as Philadelphia have reported spikes in norovirus outbreaks, prompting public health officials to urge residents to take precautions, NBC Philadelphia reported.

“Data from the northeastern region of the United States look similar to what we would expect for this time of year,” says a CDC spokesperson.

After the Northeast, the next hardest-hit region in the U.S. is the West, which saw a three-week positivity rate of around 12%, according to the CDC.

“We’re also seeing a big spike in California,” Dr. Joanna Turner Bisgrove, a family medicine physician and assistant professor at RUSH University Medical Center, tells TODAY.com.

Why is norovirus surging?

Norovirus cases and outbreaks are most common between April and November. “Norovirus is actually a seasonal virus … and usually the peak within that window is between January and early March,” Dr. Ericka Hayes, senior medical director of infection prevention at Children’s Hospital of Philadelphia, tells TODAY.com.

During the colder winter months, people tend to spend more time gathered indoors, which makes it easier for infectious diseases like norovirus to spread quickly between people, says Bisgrove.

The current surge in norovirus is not surprising, the experts note, but rather an expected increase that occurs every winter in the U.S. “It’s following pretty classic trends,” says Bisgrove.

Last winter was a tough norovirus season for the U.S., as virus activity rebounded to pre-pandemic levels following the dropping of COVID-19 restrictions. Cases peaked in early March 2023, but norovirus activity still remained high well into the spring.

In 2023, norovirus outbreaks also surged on cruise ships, reaching the highest levels seen in over a decade.

“Compared to the past years, we are in the same neighborhood, if not a little bit more (in terms of) the number of outbreaks in the region and nationally, but we are well within the normal range,” says Hayes.

How does norovirus spread?

“Norovirus is an extraordinarily contagious virus. It’s one of the most contagious kind of pathogens, viral or bacterial,” says Hayes.

Infected people shed billions of norovirus particles in their stool and vomit, and it only takes a few virus particles to make another person sick, Hayes adds.

People typically get norovirus when these tiny particles end up in their mouths, TODAY.com previously reported. This can occur through direct person-to-person contact, consuming contaminated food or liquids, or touching contaminated surfaces then putting your unwashed fingers in your mouth.

It can spread rapidly through schools, day cares, nursing homes and other enclosed settings where people are gathered close together, says Bisgrove. Norovirus is also the leading cause of foodborne illness outbreaks in the U.S., per the CDC.

A person who has been infected can continue to shed the virus for about two weeks after symptoms gone and they feel better, says Bisgrove.

Norovirus symptoms

These are the most common symptoms of norovirus in children and adults, according to the experts:

• Vomiting
• Diarrhea
• Nausea
• Stomach cramps

Other possible symptoms include a headache, body aches and a low-grade fever, per the CDC.

The first signs of norovirus may include a sudden loss of appetite, stomach pain, or generally feeling out of it, says Bisgrove.

These are typically followed by intense vomiting and watery diarrhea, though these may occur at the same time. “It’s usually a very abrupt onset and unfortunately, there’s quite a lot of it. … Patients may have dozens of stools per day,” says Hayes.

Norovirus symptoms usually last for 24 to 72 hours. “Due to all the vomiting and diarrhea you may also feel weakness, fatigue, or lightheadedness,” says Bisgrove.

People with norovirus may become dehydrated due to the loss of fluids through vomit and diarrhea. Symptoms of dehydration include decreased urination, dry mouth, or dizziness, per the CDC. Signs in children include crying without tears, becoming fussy or suddenly lethargic and sleepy, says Hayes.

Blood in the vomit or stool is not a normal symptom of norovirus, says Bisgrove, and could be a sign of something more serious. “If you see blood, go to the emergency room,” says Bisgrove.

Norovirus treatment

There is no specific treatment or medicine for norovirus, and the vast majority of people will recover on their own at home, the experts note.

It’s important to rest and consume plenty of fluids and electrolytes to replenish those lost through vomiting and diarrhea, says Bisgrove. These include water, sports drinks and oral rehydration fluids — but avoid drinks with caffeine or alcohol until you recover.

“We also recommend bland, simple foods (rice, bananas, broths) that (the) body can handle and are more likely to stay down,” says Bisgrove.

If symptoms become severe, persist for longer than a few days, or you are unable to keep fluids down or urinate, seek care, says Bisgrove. Some people may need additional support or IV fluids to prevent dehydration or its complications.

Certain groups are at higher risk of developing complications, including children, the elderly and people with chronic illnesses or weakened immune systems, says Bisgrove.

Children under 5 years old and adults 85 and older are more likely to visit the emergency room, per the CDC.

Preventing norovirus

Norovirus is an incredibly hardy virus. “It’s hard to disinfect, and it’s resistant to a lot of standard cleaners,” says Narula.

Alcohol-based hand sanitizers do not work well against norovirus, the experts note, so good hand-washing is key — this means washing your hands with soap and water for at least 20 seconds, per the CDC. Wash your hands after using the bathroom, after changing diapers and before eating.

If you are sick with norovirus, the experts recommends taking the following steps to prevent spreading the virus to others:

• Stay home until you feel better
• Avoid contact with others if possible while sick
• Wash hands before touching any communal surfaces
• Clean and disinfect surfaces with bleach
• Wash laundry in hot water
• Do not prepare and handle food until at least 48 hours after symptoms stop

This article was originally published on TODAY.com