Norovirus cases are increasing in the US, particularly in the Midwest, where cases are already above levels seen in 2022, data from Centers for Disease Control and Prevention reports.
While most norovirus cases typically occur between November and April in a given year, cases in the Midwest have increased dramatically since mid-January, according to the most recent counts.
Data from the CDC showed that the three-week average of positive tests for norovirus had increased from 11.5% on January 14 to 19.5% on February 4.
Around the same time last year, the same metric averaged 10.2%.
The rise in cases reflects a national trend, where cases have also jumped in recent weeks. As of Saturday, however, the Midwest's numbers appeared to be the highest in the country.
Norovirus, often referred to as the stomach flu even though it's not related to the flu, “is a highly contagious virus that causes vomiting and diarrhea” in people of all ages, the CDC says.
But even with the numbers on the rise, the CDC says the levels are not out of the expected range.
“Norovirus cases and reported cases from both state health departments and clinical laboratories are increasing, but remain within the expected range for this time of year,” said CDC spokeswoman Kate Grusich. he told NBC News.
Grusich noted that “preventive measures implemented during the COVID-19 pandemic” may have led to lower numbers last year.
Noroviruses are the leading cause of foodborne illness in the US, the agency notes, adding that “in years when there is a new strain of the virus, there can be 50% more norovirus illnesses.”
On average, noroviruses lead to about 900 deaths each year in the US, with another 109,000 hospitalizations and 19 to 21 million reported illnesses.
So what can you do as cases rise?
Here's what you need to know:
What are the symptoms of norovirus?
According Illinois Department of Health“many of the noroviruses cause similar symptoms.”
Onset usually occurs within 24 to 48 hours after exposure. These symptoms include:
- Motion sickness
- Vomiting
- Diarrhea
- Abdominal pain
- Body aches
- Headache
- Fatigue
- Low fever
“Symptoms usually last 24 to 60 hours and resolve on their own,” states the Illinois Department of Public Health. “There are no known long-term effects after recovery from this infection.”
How does it spread?
IDPH notes that only humans can transmit norovirus as “these viruses do not multiply outside the human body.”
They can be spread through lack of hand washing and food handling, contaminated drinking water, shellfish, and possibly through “faeces-contaminated” objects.
“You can get norovirus by accidentally taking tiny particles of feces (feces) or vomit from an infected person into your mouth,” the CDC states.
When are people with norovirus most contagious?
The CDC reports that people with norovirus are most contagious while they have symptoms, especially vomiting, and during the first few days after they recover. However, the agency notes that some studies have shown that people can still transmit the virus for two weeks or more after symptoms subside.
Is there a cure for norovirus?
There is no specific treatment or medication available for people with norovirus, but experts say that those who experience vomiting or diarrhea should drink plenty of fluids to prevent dehydration.
How can I prevent norovirus?
Experts say practicing good hygiene may be the key to preventing noroviruses.
Illinois health officials recommend the following:
- Wash your hands often, especially after using the toilet or changing diapers and before eating or preparing food.
- Wash fruits and vegetables and steam oysters thoroughly before eating.
- Thoroughly clean and disinfect contaminated surfaces immediately after an episode of diarrhea or vomiting using a bleach-based household cleaner. If you use liquid household bleach that is prepared daily, one part bleach to nine parts water (1:10 dilution) is recommended.
- Immediately remove and wash clothing or linens that may be contaminated with feces or vomit (use warm soapy water).
- Flush or flush any vomit and/or faeces down the toilet and ensure the surrounding area is kept clean.
- People infected with norovirus should refrain from preparing food while they have symptoms and for three days after they recover from their illness.
