A highly contagious and discomfort-causing virus is spreading across the United States just before the holidays.
This is not about the flu or COVID, which have also had more cases recently. It is norovirus, which has been nicknamed the December vomiting disease because it usually occurs until that month.
But since mid-October there are records that infections of this virus are on the rise, especially in states such as Louisiana, Michigan and Indiana, according to data from the WastewaterSCAN program managed by Stanford and Emory universities.
Concentrations of the virus in wastewater have grown 69% nationally as of Nov. 21, according to Amanda Bidwell, WastewaterSCAN’s chief scientist.
“We are currently in a high contagion category,” he said, with notable peaks in the Northeast and Midwest of the country.
So far, 153 norovirus outbreaks have been reported between August and November, which, although it is a high number, is lower than the record that occurred last year with 235 outbreaks in the same period of time, attributed mainly to the GII.17 variant, which specialists say seems to have mutated such that it became more contagious.
Bidwell said infections are likely to continue to rise this year as the norovirus season, which typically lasts into April, extends.
(Why Norovirus is So Hard to Kill: How to Protect Yourself from the “Perfect Pathogen”)
The Centers for Disease Control and Prevention (CDC) monitors norovirus through reports voluntarily issued by local health departments and clinical laboratories, but Bidwell points out that checking wastewater can offer a more comprehensive look because many people do not go to doctors.
Checking sewer virus levels “is an unbiased way to see what’s happening in communities,” Bidwell said.
Here’s what you need to know about norovirus this year:
A variant that worries
For more than three decades, norovirus outbreaks in the United States have been primarily of the GII.4 strain, until last year, when the GII.17 variant contributed to 75% of cases.
The rise of GII.17 may be behind the fact that more outbreaks have been recorded in 2024 than in the previous 10 years and may also be the reason why there have been cases this year since October in the United States.
“The two possibilities are that something in the virus changed to make it more transmissible or that something in the population changed so that more people were susceptible,” Robert Atmar, a professor at Baylor College School of Medicine, said of GII.17. “It is very likely that it was a combination of both situations. What is not clear yet is if that will also be seen this year.”
Atmar said that given the infections in 2024, it is possible that there is greater immunity among certain people in the country, so there may not be the same level of outbreaks.
What are the symptoms of norovirus?
Norovirus is a highly contagious disease that only occurs in humans. Outbreaks can arise anywhere; In the United States, it is estimated that the virus causes about 20 million infections annually and is responsible for more than half of cases of foodborne illnesses.
It is spread through vomit or fecal particles on contaminated surfaces or water, as well as through infected food.
The main symptoms of norovirus are diarrhea and vomiting, and fever, stomach pain, and a cut in the body may also occur.
Older adults, young children, or people with weakened immune systems may need medical attention if they begin to experience both diarrhea and vomiting because of the risk of dehydration, according to the Mayo Clinic.
Symptoms usually occur within 12 to 48 hours after exposure and last several days. Someone who was infected can continue to carry the virus for up to two weeks after they no longer have symptoms.
How to protect yourself against norovirus
Norovirus is particularly difficult to kill, and has even been dubbed the perfect pathogen because it can survive temperatures up to 145°F (70°C).
“It’s very infectious. Typical hand sanitizers with ethanol don’t do as well against this virus,” said Craig Wilen, associate professor of laboratory medicine and immunobiology at Yale University.
So to kill norovirus, the CDC recommends washing your hands very, very well with soap; use bleach to clean possibly infected areas, and wash clothing that may have the contaminants in both hot water and detergent. It is also advisable to use gloves for these cleanings and throw away the gloves after use.
It is important to wash all fruits and vegetables well, and to cook foods such as oysters and shellfish properly, according to the CDC.
There is no specific treatment for norovirus, but it is key to drink water and possibly electrolytes to avoid dehydration.
There is no current vaccine to protect against norovirus, as there is for influenza, measles, COVID and other preventable diseases, but the company Moderna has been conducting clinical trials with a possible inoculation that have already advanced to phase 3 of studies.
