United States: Bay Area health experts are sounding the alarm as a highly contagious norovirus outbreak is actually rapidly spreading this winter. Known for causing stomach cramps, vomiting, and diarrhea, this “winter vomiting disease” is one of the most common causes of gastroenteritis, and it’s regularly hitting harder than usual. Stay alert and take precautions to protect yourself!
Even though, technically, norovirus is a wintertime virus, more cases have been reported this season in the Bay Area than in previous years and then anywhere in the United States, says John Swartzberg, a health sciences professor at UC Berkeley, to SFGATE.
As reported by the SFGATE, Swartzberg said although by early spring the virus ebbs, each winter that is not the case and it can be varying in its severity.
“So the timing of this is not unusual, but it is different,” he said. “This has been one of the worst wintering that probably for a decade or so now.”
'Stomach bug' cases surging in the Bay Area in biggest spike in years https://t.co/hpVnk7D8w6 via @SFGate
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From August 1 to December 11 in 2024, the CDC recorded 495 norovirus outbreaks across the country, compared with 363 during the same period the previous year. 2024 was during this time also reported to have the highest cases by CDC data since at least 2012. The CDC uses two or more cases from a common source to define an outbreak of the norovirus.
But in the Bay Area, it’s a Stanford University program called Wastewaters can that tracks disease signals in sewage identified high levels of norovirus at treatment plants in San Jose , Redwood City, Palo Alto, Freemont, San Francisco, San Rafael, Novato and Napa.
The region also is seeing a norovirus spike over last year: In one of the plants in San Francisco, the detection of the disease on December 28, 2024, which is the day on which the number of norovirus detected was at a high in the plant, was 458% higher than December 28 2023.
They have been also reported in the Bay Area as well as other regions in the world. Last month a seafood company in San Francisco had to pull oysters off the market because of the virus; in November, Valencia Elementary School in Aptos had to shut down for several days after several students got sick.