View Reports

norovirus infection :: Article Creator

Norovirus, Aka Stomach Flu, In 2023: What To Know About Symptoms, And Treatment

The peak of norovirus season 2023 may be over, but the highly contagious stomach bug is still circulating in the United States.

According to the most recent data from the U.S. Centers for Disease Control and Prevention, about 6% of tests for the virus are still coming back positive in the U.S., which is down from a peak of 16.4% in mid-March. That said, the current percentage of tests coming back positive is still higher than in mid-July 2022, 3.6%.

Other CDC data show the 14 state health departments that are part of its NoroSTAT surveillance program reported seven norovirus outbreaks in total for the week of June 5, 2023, the most recent data available. This was the same number as what was reported the week before, and down from a peak of 62 outbreaks in February 2023. At this point in 2022, closer to zero outbreaks were reported; for the 2020 to 2021 norovirus season, the number of outbreaks being reported at this point in the year was about the same.

Dr. Luis Ostrosky, an infectious disease specialist at UTHealth Houston and Memorial Hermann in Houston, told TODAY.Com in June that "it's not unusual to be see (norovirus) cases in April and May, (and) we are continuing to see many cases."

What's more, norovirus outbreaks on cruise ships are at their highest in 11 years, according to CDC data. There have been 13 recorded so far this year. Most recently, norovirus swept through a Viking Neptune cruise ship, sickening 110 people, about 13% of the ship's total guests. Other cruise lines that have been impacted by this year's norovirus season include Celebrity Cruises, Princess Cruises and Royal Caribbean International.

In 2022, only four norovirus outbreaks were reported on cruises. In 2021, there was only one, and there were zero reported in 2020. Before the pandemic, there were 10 reported in 2019 and 12 in 2018.

Norovirus — commonly known as the "stomach flu" — is actually a group of viruses that cause acute gastroenteritis, an inflammation of the lining of the stomach and intestines, which leads to acute vomiting and diarrhea, per the CDC. Unlike its nickname suggests, norovirus is not related to the flu or influenza viruses.

Why did norovirus surge this year?

Norovirus outbreaks are common in the U.S., Kate Grusich, CDC spokesperson, told TODAY.Com in a statement in February. Each year, norovirus causes 19 to 21 million cases of vomiting and diarrhea, 109,000 hospitalizations and 900 deaths, per the CDC.

Although norovirus can spread year-round, it has a wintertime seasonality in the U.S., said Grusich, so cases tend to peak during the colder months. The vast majority of outbreaks occur between November and April, according to the CDC.

The CDC data show that norovirus cases peaked between February and March of 2023. One CDC chart shows that cases during the peak of the 2023 norovirus season were lower than they were in 2022 but higher than in 2021.

CDC data comparing norovirus outbreaks in 2023, 2022 and 2021.CDC

Dr. Ali Alhassani, a pediatrician at Boston Children's Hospital and head of clinical at Summer Health, told TODAY.Com in February that norovirus cases at the time were going up "quickly" and it started "pretty suddenly."

Ostrosky also told TODAY.Com back in February that "norovirus activity (was) higher and earlier than usual, but definitely not a big outlier compared to pre-pandemic levels."

The reason for the surge may be due to children who managed to evade norovirus over the past few years who were then exposed to norovirus and many other viruses that tend to peak and circulate among schools in the winter and early spring.

"We've always had seasonal increases and waves of norovirus, and our hospitals would be filled with kids," Dr. Albert Ko, infectious disease physician and professor of public health, epidemiology and medicine at Yale School of Public Health, tells TODAY.Com. "What kind of took us off was the pandemic," Ko adds.

Prevention measures implemented to curb COVID-19 were likely effective in preventing norovirus outbreaks, said Grusich, and as restrictions have relaxed, the number of outbreaks returned to levels similar to pre-pandemic years.

How does norovirus spread?

Norovirus is transmitted primarily "when bacteria or viruses shed in stool ends up on our hands and surfaces and then eventually ends up in our mouth and we ingest it and get infected," said Alhassani.

Norovirus may be transmitted directly from an infected person or from contaminated surfaces, objects, foods or drinks.

"Anybody who is in close contact with someone who has an active infection with norovirus is at high risk of getting it," said Alhassani. Norovirus can spread through activities like caring for an infected person, changing diapers or sharing utensils.

"Norovirus is so infectious that even if somebody throws up and there's droplets of vomit aerosolized in the air, that can actually cause infection," Alhassani added.

It takes a very small number of virus particles to transmit the disease, said Ko, which is why norovirus causes so many explosive outbreaks. Per the CDC, less than 100 norovirus particles can make you sick, and infected people typically shed billions of particles.

Most people are infectious from the time symptoms begin until about two or three days after symptoms resolve, Ko said, but some people can remain contagious or up to two weeks after recovery.

Outbreaks often occur in schools, day cares, nursing homes and cruise ships, the experts noted.

What are the symptoms of norovirus?

The most common symptoms of norovirus are vomiting, nausea, diarrhea and abdominal pain, said Ko. Other possible symptoms include a headache, body aches and a low-grade fever. Norovirus symptoms usually develop within 12 to 48 hours after exposure, per the CDC.

"Norovirus ... Will just last a few days," said Ostrosky. "For the majority of the population, it's going to be just a nuisance."

Those at higher risk of developing severe or prolonged symptoms include babies, the elderly and the immunocompromised, said Ostrosky. If symptoms transition into chronic diarrhea and weight loss, this can lead to complications like dehydration or poor absorption of medications, he added.

What is the treatment for norovirus?

"There's actually no specific treatment or antiviral for norovirus," said Ostrosky. Hydration is key to replenish fluids lost from vomiting and diarrhea, the experts noted, which means drinking plenty of water, Pedialyte or sports drinks.

"Then it's just eating bland foods and trying to let it pass through the body, which usually takes like one to three days," said Alhassani, adding that over-the-counter anti-nausea medicine and pain relievers may also be used to ease symptoms.

"The vast majority of people can be managed at home and, in fact, should be isolated at home until they're improving, given how contagious norovirus can be," said Ostrosky.

However, it's important to watch for signs of severe dehydration and to contact a health care provider if these occur, the experts noted. These include dry mouth, decreased urination, dizziness and, in children specifically, crying without tears, fussiness or unusual sleepiness, per the CDC.

Children under 1, people who are immunocompromised, or those with prolonged or severe symptoms should also be seen by a physician, said Alhassani. "While it infects many people, (norovirus) tends to not send as many people into the hospital and certainly the ICU," he added.

A person can be infected with norovirus multiple times in their lifetime. After recovering, you may possibly develop some short-term immunity, said Ko, but it won't be robust and wanes quickly.

"It's only partial immunity ... Because there are different types of norovirus, and being exposed to one doesn't give you complete protection to another," he explained.

To prevent norovirus infection, don't make this mistake

There's no vaccine against norovirus, said Ko, but there are steps you can take to prevent infection and transmission.

Hand hygiene is extremely important — but the way you clean your hands matters, Ostrosky noted, and it has to be with soap and water. Hand sanitizer does not work against norovirus.

"Norovirus is one of the few viruses that doesn't get deactivated by alcohol. You actually need to use soap and water to physically destroy it and remove it from your hands," said Ostrosky.

Wash your hands after using the restroom, before eating or cooking and after caring for someone with norovirus.

When cleaning surfaces or objects that may be contaminated with norovirus, Ostrosky suggested using a high-level disinfectant like bleach.

If you or your child are sick with norovirus, isolate to prevent the virus from spreading within the household, said Alhassani. Anyone sick with norovirus should stay home until they feel better. "Avoid food preparation until at least 48 hours after symptoms stop," said Grusich.

"We can expect to continue seeing more viral illnesses, both respiratory and gastrointestinal, in this post-COVID era we're sort of approaching," said Ostrosky, adding that the basics of hand-washing, isolation and respiratory etiquette can go a long way.

Caroline Kee

Caroline Kee is a health reporter at TODAY based in New York City.

Norovirus Cruise Ship Outbreaks Already Reach 10-Year High In 2023

There have already been an unlucky 13 recorded norovirus outbreaks on cruise ships under U.S. ... [+] jurisdiction so far in 2023. (Photo by Finnbarr Webster/Getty Images)

Getty Images

Talk about being ship out of luck. There have already been an unlucky 13 recorded norovirus outbreaks on cruise ships under U.S. Jurisdiction so far in 2023. That's the highest tally in 10-years, ever since 16 such outbreaks occurred in 2012, according to the Centers for Disease Control and Prevention (CDC) Vessel Sanitation Program. And with half of 2023 still to go, there's a good chance that the 2012 count will be surpassed sometime later this year.

Nearly every month this year has had its ship outbreaks. There were already three outbreaks by February 3 of this year, seven that crossed the month of March, and two in May. June had one as well, affected a Viking Cruises ship that traveled from June 6 to June 20. This outbreak left 110 of 838 (13.1%) passengers and nine of 455 (1.98%) crew members sick in a bad way. Norovirus outbreaks have hit ships from a range of different cruise ship companies including Viking Cruises, Celebrity Cruises, Holland America, Princess Cruises, Royal Caribbean International, and P&O Cruises. Yeah, even though norovirus is known as the "Winter vomiting bug," it's activity is not necessarily confined to the colder months.

The "vomiting" should be a tip off as to what may happen when you get infected with norovirus. Such infections are a match made in heaving, so to speak. The most common symptoms of a norovirus infection are nausea, vomiting, diarrhea, and stomach cramping. You can also get a low-grade fever, chills, a headache, and muscle aches. Such symptoms tend to emerge rather suddenly about one or two days after the virus has gone down your pie hole.

And these symptoms can be quite severe too. Norovirus often isn't just your typical I'm-feeling-a-little-sick-so-I-may-pass-on-shuffleboard type of gastroenteritis. No, a norovirus infection can consist of projectile vomiting and explosive diarrhea. Projecting your voice, feelings, or insecurities is one thing. Projecting you vomit is something completely different. Similarly, you've got to be careful about anything that could explode in your pants.

Norovirus is also known as the "Cruise ship virus" because conditions on cruise ships can stack the deck for the spread of norovirus, so to speak. Typically, a cruise ship will have dozens, hundreds, and in some cases thousands of people sharing surfaces, objects, food, drink, and who-knows-what-else over extended period of times. If anyone brings about the virus, it could readily spread rapidly. Norovirus is highly infectious, as I've described for Forbes previously. Just 18 virus particles can get you infected. Plus, hand sanitizer and cleaning materials that don't contain something more powerful like bleach may not get rid of the virus from a surface.

Railings can be high touch surfaces that can help transmit norovirus. (Photo: Getty)

getty

It's really not that surprising that norovirus outbreaks have already reached a high water mark this year. As many Covid-19 precautions went the way of sweater vests in late 2022, it's probably not a coincidence that this past winter saw a surge of norovirus cases in general, as I reported for Forbes on February 10, 2023. On top of that, cruise ships returned to full operations for the entire calendar for the first time since early 2020. Throw in the whole idea of "revenge travel" with people scrambling to catch up on travel delayed by the pandemic, and you've got a bunch of set ups for norovirus outbreaks.

So if you are about to go cruising, how do you avoid getting a norovirus infection, beside, of course, not going on the cruise? One is to wash your darn hands frequently and thoroughly. Use soap and water since hand sanitizer may not kill or inactivate the virus. Just because many have eased up on Covid-19 precautions doesn't mean that you should stop washing your hands. If you have stopped washing your hands, please don't go to any parties, ever.

Secondly, clean and disinfect high touch surfaces such as doorknobs, faucets, handles, and that statue of Dwayne "The Rock" Johnson in the dining hall. Use either a chlorine bleach solution that has a concentration of at least 1,000 to 5,000 parts per million or use a disinfectant that's registered with the Environmental Protection Agency (EPA) as being effective versus norovirus.

Finally, if someone appears sick, keep you distance. For example, should someone tell you, "I am having some explosive diarrhea, but should still be able to dance with you," tell them that "explosive diarrhea" is not something that you want to dance around.

Norovirus And E. Coli: What You Need To Know

Outbreaks of foodborne illness sicken millions of people across the U.S. Each year.

There are a couple of main culprits involved: norovirus and E. Coli. Although they can both cause miserable gastrointestinal symptoms, they're very different in some important ways.

Here's what you need to know about both:

Norovirus

Norovirus is the most common type of foodborne illness in the U.S., according to the Centers for Disease Control and Prevention. Anywhere from 19 to 21 million Americans are infected with the virus each year, and norovirus contributes to up to 109,000 hospitalizations, 465,000 ER visits (mostly involving children), and about 900 deaths a year. Most of the fatalities occur among people age 65 or over.

Norovirus is extremely contagious, infectious disease expert Dr. Amesh Adalja told CBS News. Past studies have shown that the majority of outbreaks occur when food is contaminated by food service workers.

When a person contracts norovirus, the symptoms come on quickly. It has a shorter incubation period compared with E. Coli.

"With norovirus, it's a very abrupt onset — within a day or two — and vomiting is the predominant symptom," said Adalja. "People often have violent vomiting," but it's over within a couple of days.

Foodborne illness: The most guilty foods list 10 photos

Norovirus — which has a reputation for making the rounds on cruise ships — can be spread through an infected person, contaminated food or water, or by touching surfaces where the virus particles lurk and then touching your mouth.

It causes your stomach and intestines to become inflamed — what doctors call acute gastroenteritis — and other than vomiting, symptoms can include stomach pain, nausea and diarrhea. Fever, a headache and body aches may occur, too, the CDC says.

The best way to stop norovirus in its tracks is to wash your hands, especially after using the bathroom and changing diapers, but also before eating and when preparing food. Service workers — especially restaurant employees who handle food — can help reduce infection rates if they practice good hand hygiene.

If norovirus takes you down, antibiotics won't help, since they only fight bacterial infections, the CDC says. It's important to stay hydrated with lots of water and other non-caffeinated beverages to fend off dehydration that can come from fluid loss due to vomiting and diarrhea.

Symptoms generally ease after one to three days, and when you're ready to eat again, Dr. Alexandra Sowa recommends what's called a BRAT diet: "A very bland diet: bananas, rice, applesauce and toast," she said.

As you recover, CDC recommends cleaning and disinfecting surfaces so that you don't pass the virus on to others. Use a chlorine bleach solution with a concentration of five to 25 tablespoons of household bleach per gallon of water.

E. Coli

E. Coli is a common bacteria that can be present in undercooked and raw foods, such as rare ground beef, vegetables grown in cow manure or washed in contaminated water, fruit juice that isn't pasteurized, or even water that you swim in.

There are different types of E. Coli, some harmless and some not so harmless. Harmless E. Coli normally live inside the intestines and help the body break down and digest food.

But some strains of E. Coli are linked with diarrheal disease, including Shiga toxin-producing E. Coli and enterohemorrhagic E. Coli. Dangerous forms of E. Coli like the one involved in dozens of cases linked to a Chipotle outlet in Boston in 2015, can make people very ill.

E. Coli O157:57 is the form of E. Coli doctors typically see in foodborne illness cases, said Adalja.

He said it secretes toxins and those toxins can cause kidney failure in some patients; 12% of those with kidney failure will either die or end up on dialysis. Children and older people are especially vulnerable to more serious cases.

"The Chipotle outbreak is an O26 [strain] that has the same capacity to secrete the toxins that can lead to kidney failure and hemolytic uremic syndrome," said Adalja.

The symptoms of E. Coli illness are, like norovirus, belly-related, but different enough so that doctors can usually tell the two apart from each other easily.

Where norovirus's severe vomiting typically strikes within one to two days, E. Coli usually takes three to four days to incubate before its signature symptom — bloody diarrhea — and abdominal cramps begin, said Adalja.

"With E. Coli, people don't vomit. It isn't predominant. It's the bloody diarrhea, not the watery diarrhea from norovirus, and abdominal cramps, fever. It's not similar. Most clinicians would not confuse the two," he said.

E. Coli symptoms may last about a week before patients start to feel better again. But recuperation can vary depending on a person's age and general immune system health, said Adalja.

Heat can kill illness-causing E. Coli bacteria, so cooking beef well until it's no longer pink, and choosing pasteurized juices (the process uses heat to kill germs) can reduce the risk of getting sick, the CDC says.

And because waste (human and animal) carries lots of bacteria, the CDC recommends washing hands with soap and warm water well after using the bathroom and before eating or preparing food to help avoid spreading E. Coli.

This is an updated version of an article originally published Dec. 10, 2015.