In early December, the Centers for Disease Control and Prevention reported twice as many norovirus cases as in previous years, following widespread outbreaks.
During the week of December 5, the CDC reported 91 cases of norovirus, also known as stomach flu, more than doubling the highest number recorded between 2021 and 2024.
The report follows a press release from the Minnesota Department of Health, which stated that Minnesota saw double the average number of stomach flu cases in December.
As cases increase, here’s what to know about norovirus.
What is norovirus?
Norovirus is more commonly known as the stomach flu, and is the leading cause of vomiting and diarrhea from inflammation of the stomach and intestines, or gastroenteritis, according to the CDC.
The virus is also the leading cause of foodborne illness in the United States, accounting for 58% of all illnesses acquired.
Norovirus recently found on cruise ships, at food events
More than 80 people were reported to have become ill this month after eating oysters at the Los Angeles Times 101 Best Restaurants event, according to USA TODAY.
Oysters from British Columbia, Canada, were also recalled after the US Food and Drug Administration issued several advisories warning that the shellfish could be contaminated with the virus.
Norovirus outbreaks have also been reported on several cruise ships this month.
On a Holland American Line cruise that departed Fort Lauderdale on December 8 and ended on December 20, 83 guests and a dozen crew members reported feeling ill. Their primary symptoms were vomiting and diarrhea.
The outbreak came after two separate norovirus outbreaks on Princess Cruises’ Ruby Princess, which ended on December 18, and a cruise on Holland America’s Zuiderdam that ended on December 14.
Seniors and children most affected by norovirus
While anyone can contract the virus, it affects certain age groups more severely than others.
People who are more likely to visit an outpatient or emergency department department are children 5 years and younger or seniors over the age of 85, according to the CDC.
The virus is is responsible for almost a million pediatric medical care visits, according to the CDC.
What are the symptoms of norovirus illness?
The Minnesota Department of Health and the Cleveland Clinic list the following symptoms of norovirus infection:
- Vomiting
- Diarrhea
- Stomach cramping
- Urinating less or having dark-colored pee
- Dry mouth
- Feeling weak
- Dizziness
Less common symptoms are:
- Low-grade fever or chills
- Headache
- Muscle aches
A person who is sick and has been infected with the virus will usually develop symptoms suddenly.
“The infected person may feel very sick and vomit often, sometimes without warning, many times a day,” according to the department.
Children infected with the virus may be fussy, sleepy all day, and cry without tears.
When do norovirus symptoms appear?
According to the Minnesota Department of Health, people will develop symptoms one to two days after being exposed to the virus. However, symptoms can appear up to 12 hours after ingestion.
The illness usually lasts from one to two days.
While some people infected with the virus may experience unpleasant symptoms, others may be symptomatic or exhibit no symptoms at all. They can still be contagious and transmit the virus to others.
How does norovirus spread?
According to the Cleveland Clinic, the highly contagious virus can be contracted in the following ways:
- Consuming foods or drinks contaminated with the virus
- Being in close contact with an infected person
- Touching their mouth or nose after touching contaminated surfaces
People are more likely to spread the virus to others with whom they share food or utensils, as well as those with whom they have close contact or care for.
The virus can be contracted at any time of year, but it is most commonly spread between November and April, according to the CDC. When a new strain of the virus emerges, 50% more cases of illness occur.
What to do if you have norovirus
While it may be difficult, people infected with the virus should continue to eat and drink throughout the day, according to the Cleveland Clinic.
The CDC advises those infected with the virus to stay hydrated and drink fluids frequently. Sports drinks like Gatorade or Body Armor can help with rehydration, but they may not replenish nutrients and minerals in the same way that oral rehydration fluids like Pedialyte can.
The CDC advises against taking antibiotics because they will not treat the virus.
How to stop the spread of the illness
The following are way to prevent the spread of norovirus, according to the CDC:
- Stay at home for at least two days after symptoms stop if you’ve been infected
- Wash hands often for at least 20 seconds with soap and water
- Washing laundry in hot water
- Clean and disinfect any contaminated surfaces
- Thoroughly clean produce, like fruits and vegetables, and shellfish
Make sure to always wash your hands after doing the following:
- Touching common surfaces, like elevator buttons or door handles.
- Shaking hands with another person
- Caring for a sick person
- Changing diapers
