Bay Area still battling ‘extremely contagious’ norovirus

Norovirus, sometimes referred to as the stomach flu or the “cruise ship virus,” is still in high circulation in several Bay Area regions, and health experts say that rates could increase with the impending FIFA World Cup. 

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WastewaterSCAN, which monitors the rates of several viruses throughout the Bay Area’s municipal wastewater, shows that traces of norovirus are at high levels in Palo Alto, San Jose, Fremont, Vallejo and Novato as of Thursday. Meanwhile, the virus has a moderate presence in several other regions, including San Francisco. 

Regardless, Dr. Matthew Willis, a former health officer for Marin County, said it’s too early to tell whether we’re in for a rough summer. Norovirus is present all year long, he said, but rates are “higher than we normally see in June,” which is “true for multiple jurisdictions at once,” Willis told SFGATE Thursday. 

“This does seem to be more of a pattern across the region,” he continued. He also warned that rigorous hand-washing will be crucial as international travelers visit the Bay Area for the World Cup, which is taking place this summer. 

Described by health experts as “extremely contagious,” the virus, which causes symptoms like vomiting, stomach cramps and diarrhea, commonly spreads in medical facilities, restaurants, childcare centers and cruise ships. Per the Centers for Disease Control and Prevention, norovirus causes 90% of diarrheal outbreaks on cruises, which is how it earned its unfortunate nickname. Because these ships have shared dining areas and small cabins, it’s difficult to control the spread once it begins. According to the CDC, about 2,500 norovirus outbreaks are reported across the U.S. each year.

Another reason it spreads so easily is that it takes only 10 viral particles to make someone sick, compared with the flu, which requires thousands, Willis said. It’s “so infectious,” he told SFGATE.

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Additionally, the stubborn virus can stay on surfaces for days or weeks at a time, and is resistant to many common disinfectants. As a result, the CDC recommends using a chlorine bleach solution to kill any particles that linger on surfaces. Because hand sanitizer isn’t very effective in combating norovirus either, the agency recommends that individuals thoroughly wash their hands with soap and water. It can also stay in feces for two weeks or more after symptoms improve, and can still infect other people during this period. Symptoms typically manifest 12-48 hours after exposure, and last up to three days. 

The virus, which is heat-resistant, can even survive grueling temperatures of 145 degrees, and quickly steaming contaminated food won’t get rid of it. “It takes so little virus to create more cases,” Willis said, adding that if anyone in the house is sick with the illness, family members should “obsessively” wash their hands. 

For more information on how to prevent the spread of norovirus, visit the Centers for Disease Control website.