Norovirus, sometimes called the “winter vomiting disease” or “two-bucket disease” — because it causes both vomiting and diarrhea — is on the rise across the nation, even as seasonal flu is taking off and walking pneumonia rages on.
Wastewater data and reports from the Centers of Disease Control and Prevention have shown a significant spike in norovirus in the last few weeks, with rates far exceeding those of the past few years.
At least 91 outbreaks were reported the week of Dec. 5, more than double the maximum number of outbreaks reported in the same time frame over the last several years.
What is norovirus and how can you stay protected?
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What is norovirus?
Noroviruses have been called “the perfect human pathogens.” They’re a type of highly contagious stomach bug that causes severe vomiting and diarrhea, along with headache, fever and body aches. It spreads fast and far on surfaces and through the air in tiny droplets of vomit. Most people fully recover, but only after days of misery. Because it mutates, people can get sick with a norovirus every year.
Outbreaks can occur at any time, but are most common from November to April.
The virus travels in vomit and diarrhea. It spreads by direct contact with someone who has norovirus, or by touching contaminated surfaces and then putting your fingers in your mouth. Contaminated food or liquids can also spread the virus.
Shellfish, especially oysters and clams, are also known to spread the bug, because they are filter feeders and can accumulate the virus from untreated sewage flowing into their habitats.
What are norovirus symptoms? How long do they last?
Symptoms begin 12 to 48 hours after exposure to the virus and last for about 1 to 3 days. Even after recovering, infected individuals can be contagious for two more weeks.
One of the dangers of prolific vomiting and diarrhea is the loss of fluids, which can lead to severe dehydration. This is something to watch out for in children and the elderly in particular — children may not produce tears when crying, or be unusually fussy or sleepy, if they are dehydrated.
There is no specific medicine that is used to treat the disease. Instead, symptoms can be managed with oral rehydration solutions like Pedialyte, which can help restore fluids and electrolytes that are lost from the body.
Why is norovirus so hard to kill?
The most reliable way to stop the spread is washing your hands with soap and water for at least 20 seconds, especially if you are preparing food, or after using the restroom or changing diapers.
Hand sanitizer is not very effective against norovirus. While many viruses are contained in “envelopes” that are made of fat and can be broken by alcohol-based sanitizers, norovirus is contained in a hardy protein shell called a capsid. It's not as easily wiped out by alcohol disinfectants.
Cruises, which had a banner year in 2024, are often associated with norovirus, due to the close quarters and shared facilities, but the virus is not restricted to cruise ships. Nursing homes, hospitals, jails, and preschools can all be sites of an outbreak.
Avoiding raw or undercooked shellfish can also reduce the risk of infection. Since norovirus can survive temperatures up to 145°F, quick steaming will not kill the virus.
Even if you have had norovirus before, you can still be infected every year, because there are many different types of the bug, owing to the rapid mutation rate seen in RNA viruses like norovirus.
Norovirus is notoriously difficult to clean because it can stay on surfaces for weeks to months. It is important to wear gloves and use bleach when disinfecting a contaminated surface, such as one that has been in contact with vomit or diarrhea. Bleach should be left on the area for at least five minutes.
Use disposable paper towels, rather than reusable rags, when cleaning a contaminated surface.
Clothes or bedding used by someone with norovirus should be handled with gloves and washed with detergent and hot water for as long as possible at the highest heat setting.
There’s currently no approved vaccine for norovirus, although Moderna has begun a phase three trial in the U.S. for a vaccine using mRNA technology and aims to test it in 25,000 adults worldwide. Norovirus causes about 200,000 deaths worldwide each year.
This story first appeared on NBCNews.com. More from NBC News:
