Cases of norovirus are on the rise in the US, on par with seasonal trends, according to the most recent data from the US Centers for Disease Control and Prevention.
In the week ending February 17, more than 12% of tests for norovirus – a common and very contagious virus that causes gastrointestinal symptoms – came back positive, CDC data showed. That’s up from 11.5% the week before. Cases are particularly high in the Northeast, where more than 13% of tests came back positive. Positivity rates in the region have been over 13% since late January.
However, these levels are below what they were at this point last season, when about 15% of tests were positive, both nationally and in the Northeast.
Outbreaks of norovirus are most common in the late fall, winter, and early spring, according to the CDC.
Norovirus is the most common cause of acute gastroenteritis – often called a stomach bug – in the United States, according to the CDC. It causes 19 million to 21 million illnesses every year, most often in crowded environments such as nursing homes, daycare centers, and cruise ships.
It can spread when you come into direct contact with someone who’s infected, consume food or liquids contaminated with the virus, or touch contaminated surfaces and then put your fingers in your mouth. The CDC warns that an infected person can still spread norovirus two or more weeks after symptoms resolve.
The most common symptoms are diarrhea, vomiting, nausea, and stomach pain. There’s no specific treatment for norovirus, but experts recommend drinking plenty of liquids to avoid dehydration. To prevent illness, the CDC recommends washing your hands, rinsing fruits and vegetables, and cooking shellfish thoroughly.
The US Food and Drug Administration issued an advisory in January warning against the sale and consumption of certain oysters from Baja California and Mexico due to potential norovirus contamination.
In December, more than 200 suspected cases of norovirus were linked to a sushi restaurant in North Carolina.