The dreaded norovirus — the “vomiting bug” that usually causes abdomen flu signs — is climbing once more in California, and medical doctors warn {that a} new subvariant might make much more individuals sick this season.
In L.A. County, concentrations of norovirus are already on the rise in wastewater, indicating elevated circulation of the illness, the native Division of Public Well being informed the Los Angeles Occasions.
Norovirus ranges are rising throughout California, and the rise is particularly notable within the San Francisco Bay Space and L.A., in response to the California Division of Public Well being.
And the speed at which norovirus assessments are confirming an infection is rising nationally and within the Western U.S. For the week that ended Nov. 22, the take a look at positivity fee nationally was 11.69%, up from 8.66% two months earlier. Within the West, it was even worse: 14.08%, up from 9.59%, in response to the U.S. Facilities for Illness Management and Prevention.
Norovirus is very contagious, and is America’s main explanation for vomiting and diarrhea, in response to the CDC. Outbreaks usually occur within the cooler months between November and April.
Clouding the image is the latest emergence of a brand new norovirus pressure — GII.17. Such a improvement may end up in 50% extra norovirus sickness than typical, the CDC says.
“In case your immune system isn’t used to one thing that comes round, lots of people get contaminated,” stated Dr. Peter Chin-Hong, an infectious illnesses professional at UC San Francisco.
In the course of the 2024-25 winter season, GII.17 overthrew the earlier dominant norovirus pressure, GII.4, that had been liable for greater than half of nationwide norovirus outbreaks over the previous decade. The ancestor of the GII.17 pressure in all probability got here from a subvariant that triggered an outbreak in Romania in 2021, in response to CDC scientists.
GII.17 vaulted in prominence throughout final winter’s norovirus surge and was in the end liable for about 75% of outbreaks of the illness nationally.
The pressure’s emergence coincided with a very dangerous yr for norovirus, one which began unusually early in October 2024, peaked sooner than regular the next January and stretched into the summer season, in response to CDC scientists writing within the journal Rising Infectious Illnesses.
In the course of the three prior seasons, when GII.4 was dominant, norovirus exercise had been comparatively steady, Chin-Hong stated.
Norovirus may cause substantial disruptions — as many dad and mom know all too nicely. An elementary faculty in Massachusetts was pressured to cancel all lessons on Thursday and Friday due to the “excessive quantity of abdomen sickness instances,” which was suspected to be pushed by norovirus.
Greater than 130 college students at Roberts Elementary College in Medford, Mass., have been absent Wednesday, and directors stated there in all probability wouldn’t be a “affordable variety of college students and employees” to renew lessons Friday. An organization was employed to carry out a deep clear of the college’s school rooms, doorknobs and kitchen gear.
Some locations in California, nonetheless, aren’t seeing main norovirus exercise up to now this season. Statewide, whereas norovirus ranges in wastewater are rising, they nonetheless stay low, the California Division of Public Well being stated.
There have been 32 lab-confirmed norovirus outbreaks reported to the California Division of Public Well being up to now this yr. Final yr, there have been 69.
Officers warning the numbers don’t essentially replicate how dangerous norovirus is in a selected yr, as many outbreaks should not lab-confirmed, and an outbreak can have an effect on both a small or giant variety of individuals.
Between Aug. 1 and Nov. 13, there have been 153 norovirus outbreaks publicly reported nationally, in response to the CDC. Throughout the identical interval final yr, there have been 235.
UCLA hasn’t reported a rise within the variety of norovirus assessments ordered, nor has it seen a major enhance in take a look at positivity charges. Chin-Hong stated he likewise hasn’t seen an enormous enhance at UC San Francisco.
“Issues are comparatively nonetheless steady clinically in California, however I believe it’s just a few period of time earlier than it comes right here,” Chin-Hong stated.
In a typical yr, norovirus causes 2.27 million outpatient clinic visits, largely younger kids; 465,000 emergency division visits, 109,000 hospitalizations, and 900 deaths, largely amongst seniors age 65 and older.
Individuals with extreme ongoing vomiting, profound diarrhea and dehydration might have to hunt medical consideration to get hydration intravenously.
“Kids who’re dehydrated could cry with few or no tears and be unusually sleepy or fussy,” the CDC says. Sports activities drinks may help with delicate dehydration, however what could also be extra useful are oral rehydration fluids that may be purchased over-the-counter.
Kids below the age of 5 and adults 85 and older are most definitely to wish to go to an emergency room or clinic due to norovirus, and shouldn’t hesitate to hunt care, consultants say.
“Everybody’s in danger, however the individuals who you are concerned about, those that we see within the hospital, are the very younger and really previous,” Chin-Hong stated.
These at highest danger are infants, as a result of it doesn’t take a lot to trigger probably critical issues. Newborns are in danger for necrotizing enterocolitis, a life-threatening irritation of the gut that just about solely impacts new infants, in response to the Nationwide Library of Drugs.
Whereas wholesome individuals usually clear the virus in a single to 3 days, immune-compromised people can proceed to have diarrhea for a very long time “as a result of their physique’s immune system can’t neutralize the virus as successfully,” Chin-Hong stated.
The principle manner individuals get norovirus is by by chance ingesting water or consuming meals contaminated with fecal matter, or touching a contaminated floor after which putting their fingers of their mouths.
Individuals often develop signs 12 to 48 hours after they’re uncovered to the virus.
Hand sanitizer doesn’t work nicely towards norovirus — that means that correct handwashing is important, consultants say.
Individuals ought to lather their fingers with cleaning soap and scrub for at the least 20 seconds, together with the again of their fingers, between their fingers and below their nails, earlier than rinsing and drying, the CDC says.
One useful approach to hold observe of time is to hum the “Blissful Birthday” tune from starting to finish twice, the CDC says. Chin-Hong says his favourite is the refrain of Kelly Clarkson’s “Since U Been Gone.”
When you’re dwelling with somebody with norovirus, “you actually have to scrub surfaces and stuff in the event that they’re touching it,” Chin-Hong stated. Contamination is shockingly simple. Even simply respiration out little saliva droplets on meals that’s later consumed by another person can unfold an infection.
Throw out meals that could be contaminated with norovirus, the CDC says. Noroviruses are comparatively immune to warmth and may survive temperatures as excessive as 145 levels.
Norovirus is so contagious that even simply 10 viral particles are sufficient to trigger an infection. In contrast, it takes ingesting hundreds of salmonella particles to get sick from that bacterium.
Individuals are most contagious when they’re sick with norovirus — however they will nonetheless be infectious even after they really feel higher, the CDC says.
The CDC advises staying house for 48 hours after an infection. Some research have even proven that “you possibly can nonetheless unfold norovirus for 2 weeks or extra after you are feeling higher,” in response to the CDC.
The CDC additionally recommends washing laundry in sizzling water.
Moreover faculties, different locations the place norovirus can unfold shortly are cruise ships, day-care facilities and prisons, Chin-Hong stated.
The newest norovirus outbreak on a cruise ship reported by the CDC is on the ship AIDAdiva, which set sail on Nov. 10 from Germany. Out of two,007 passengers on board, 4.8% have reported being sick. The outbreak was first reported on Nov. 30 following stops that month on the Isle of Portland, England; Halifax, Canada; Boston; New York Metropolis; Charleston, S.C.; and Miami.
In response to CruiseMapper, the ship was set to make stops in Puerto Vallarta on Saturday, San Diego on Tuesday, Los Angeles on Wednesday, Santa Barbara on Thursday and San Francisco between Dec. 19-21.
