Science
The FDA knew long ago that red dye No. 3 causes cancer. Why did it take so long to ban it?
The Food and Drug Administration said Wednesday that the much-maligned red dye No. 3 will be banned in the United States because it has been shown to cause cancer in animals.
The decision, lauded by consumer advocacy groups, comes a full 25 years after scientists at the agency determined that rats fed large amounts of the artificial color additive were much more likely to develop malignant thyroid tumors than rats who weren’t given the food coloring. They also had an increased incidence of benign tumors and growths that can be precursors to cancer.
Those findings prompted the FDA to declare in 1990 that red dye No. 3 could not be used in cosmetics or drugs applied to the skin. The reason for the decision was clear: A federal law known as the Delaney clause says no color additive can be considered safe if it has been shown to cause cancer in animals or people.
Yet the dye remained a legal food coloring. It’s in the bright red cherries that dress up a bowl of Del Monte’s fruit cocktail. It makes Nesquik’s strawberry milk a pleasing shade of pink. It also colors beef jerky, fruit rolls, candy, ice cream and scores of other processed products.
Now food makers will have two years to reformulate their products without red dye No. 3. Drug companies have three years to remove it from their medicines.
The FDA does not seem to be bothered by the fact that this cancer-causing chemical will linger in the food supply. The agency’s view is that the biological process through which the dye causes cancer in rats doesn’t occur in people.
“We don’t believe there is a risk to humans,” Jim Jones, the FDA’s deputy commissioner for human foods, told members of Congress last month.
In announcing the ban, the agency added that people consume red dye No. 3 at levels far lower than those shown to cause cancer in two studies of rats. A host of other studies in both animals and humans did not show the dye to be cancerous.
Nonetheless, regulators revoked authorization of red dye No. 3 to satisfy a petition demanding that the Delaney clause be enforced.
Starburst-flavored Fruit by the Foot, which contains red dye No. 3. (Christina House / Los Angeles Times)
“Regardless of the truth behind their argument, it doesn’t matter,” said Jensen N. Jose, regulatory counsel for food chemical safety at the Center for Science in the Public Interest, which spearheaded the effort. “Once it’s established that it causes cancer, FDA must prohibit the chemical by law.”
This wasn’t the first case of the FDA banning a food additive it considers safe to comply with the Delaney clause. The situation shows why the federal law is long overdue for a refresh, food safety experts say.
“A lot of people think we need to reform this,” said Diana Winters, deputy director of the Resnick Center for Food Law and Policy at UCLA Law. “It does lead to some absurd results.”
The Delaney clause is part of a 1958 federal law that expanded the FDA’s regulatory authority over newfangled food additives developed during World War II that were making their way into consumer products, Winters said.
Back then, members of Congress were worried about the cancer risks posed by all sorts of man-made compounds. Even small amounts seemed capable of triggering cancerous growths if people encountered them over and over again.
Arthur Flemming, who served as President Eisenhower’s Cabinet secretary for health and welfare, told Congress at the time there was no way for FDA regulators to know whether any exposure level was low enough to be truly safe. Considering the many cancer risks lurking in the environment, he said, the government should “do everything possible to put persons in a position where they will not unnecessarily be adding residues of carcinogens to their diet.”
Signature Select rainbow cups, which contain red dye No. 3.
(Christina House / Los Angeles Times)
The issue was personal for Rep. James Delaney, a Democrat from New York City whose wife was undergoing cancer treatment at the time. He made sure the new law included a zero-tolerance provision for cancer-causing substances, though it said nothing about additives that might cause other kinds of health problems.
“No additive shall be deemed to be safe if it is found to induce cancer when ingested by man or animal, or if it is found, after tests which are appropriate for the evaluation of the safety of food additives, to induce cancer in man or animal,” the Delaney clause states. A 1960 amendment governing color additives extended the rule to dyes.
As the years went by, advances in toxicology allowed scientists to expand the list of known cancerous compounds, and to identify them in ever-smaller amounts. Regulators were no longer as clueless as they’d been in Flemming’s day.
In 1986, the FDA tried to take that progress into account as it evaluated the safety of two color additives — orange dye No. 17 and red dye No. 19 — for use in lipsticks, nail polishes, face powders and other cosmetics. The agency acknowledged that both dyes were capable of inducing cancer in laboratory animals. But it argued that the regulatory decision should be guided not by a literal interpretation of an aging law but by the real-world risks to people.
When those color additives were used as intended, those risks were vanishingly small: A panel of scientists from the U.S. Public Health Service determined the lifetime cancer risk posed by the red dye was 1 in 9 million at worst; for the orange dye, it was 1 in 19 billion. In both cases, the possibility of developing cancer was “so trivial as to be effectively no risk,” the panel concluded.
A federal appeals court agreed that the dyes seemed to be safe. In fact, the risks they posed were millions of times lower than the risks of smoking, the judges wrote.
Moreover, the judges noted, forbidding the use of chemicals that carry a minute risk of cancer might prompt manufacturers to use compounds that are more toxic, albeit in noncancerous ways. Substitutions like these would be “a clear loss for safety,” they wrote.
But none of that matters, the court ruled: If a dye or any other chemical is found to cause cancer in animals, the FDA’s only option under the Delaney clause was to forbid its use.
Nestle Nesquik strawberry milk, containing red dye No. 3. (Christina House / Los Angeles Times)
Regulators found themselves in a more absurd situation in 2018 when they were asked to revoke their authorization of a flavoring additive called myrcene.
When the synthetic compound was force-fed to rats at doses of 1 gram per kilogram of body weight for two years, the animals developed kidney cancer and other forms of renal disease. Female mice fed under the same conditions developed liver cancer as well, the FDA said.
But the amount of artificial myrcene consumed by a typical American is 813,000 times lower — around 1.23 micrograms per kilogram of body weight, the agency said.
Moreover, myrcene is a natural component of mangoes, citrus juices, cardamom, and herbs including basil, parsley and wild thyme. The amount of natural myrcene in the food supply is about 16,5000 times greater than its synthetic counterpart, the agency added.
Still, the FDA declared the additive unsafe “as a matter of law” while assuring the public that no one’s health was actually at risk when synthetic myrcene was on the market. It blamed the Delaney clause for the confusion.
In 2020, a group of food industry scientists said the problem goes well beyond confusion. Revoking approval for artificial myrcene “has contributed to the ongoing erosion of trust in regulatory agencies,” they argued in the journal Regulatory Toxicology and Pharmacology. Such decisions promote an irrational fear of chemicals and cause consumers to lose faith in the safety of the U.S. food supply, they wrote.
Red dye No. 3 was approved for use in U.S. food in 1907, when it was known as erythrosine. It won permanent listing as an authorized color additive for foods, supplements and ingested drugs under the name FD&C Red No. 3 in 1969.
Soon after that decision, an industry group called the Toilet Goods Assn. petitioned the FDA to upgrade the dye’s listing for cosmetics and topical drugs from provisional to permanent. The request triggered additional tests in the 1970s and ‘80s, including two long-term feeding studies in rats.
Beginning before birth and for their entire lives, the animals were put on diets that included the red dye at concentrations of 0.1%, 0.5%, 1% or 4%. Compared to male rats that didn’t consume any dye, male rats that ate the most had a significantly higher incidence of tumors — both malignant and benign — as well as abnormal cell growth in the thyroid. No other group had an increased incidence large enough to be considered statistically significant. Among female rats, the incidence of benign tumors was elevated for those on the 1% diet, though not for rats on the 4% diet, as would be expected if the dye were the cause of cancer in these animals.
After consulting with scientists from the National Toxicology Program and the U.S. Public Health Service, the FDA concluded that red dye No. 3 could cause cancer in animals. In 1990, the agency denied the industry group’s request for permanent listing.
That decision applied only to cosmetics and topical drugs, and had no immediate bearing on food products sold in the U.S. At that point, the dye had been permanently listed as an approved food additive for decades. Nothing in those rat studies indicated to the agency that its designation needed to change.
Over the years, the dye has been tested in mice, rats, gerbils, pigs, beagles and humans. An extensive review conducted by the World Health Organization and the Food and Agriculture Organization of the United Nations found “no concerns” about the dye’s ability to trigger cancer, impair fertility or cause developmental problems in people of all ages when consumed in realistic doses.
“Claims that the use of FD&C Red No. 3 in food and in ingested drugs puts people at risk are not supported by the available scientific information,” the agency said Wednesday.
Frosted sugar cookies from Favorite Day Bakery, containing red dye No. 3.
(Christina House / Los Angeles Times)
Pitting the Delaney clause’s strict legal requirements against advances in cancer research has been a longstanding challenge for the agency, officials said.
“When we ban something, it will go to court,” Dr. Robert Califf, the FDA’s commissioner, told the Senate Health, Education, Labor and Pensions committee last month. “And if we don’t have the scientific evidence that will stand up in court, we will lose in court.”
The elaborate regulatory process for removing an additive from the food supply can certainly result in litigation, said Emily Broad Leib, director of the Center for Health Law and Policy Innovation at Harvard Law School.
“The Delaney clause probably works a lot better at the outset if you’re trying to add a new substance to food,” she said. “Once things are in food, it takes a really long time to remove it.”
The way some people see it, the problem with the Delaney clause isn’t that it forces the FDA to ban food additives that don’t pose a true cancer threat. It’s that the law doesn’t address all the other ways the foods we eat can be hazardous to our health.
“There’s a lot of things in foods naturally that cause cancer, and the Delaney clause doesn’t cover that,” said Alyson Mitchell, a food scientist at UC Davis. “It also does not speak to anything regarding other illnesses, whether it’s kidney dysfunction or ADHD or mental health issues or endocrine imbalances.”
The General Accounting Office (now known as the U.S. Government Accountability Office) raised this issue back in 1981, when it advised Congress to update the Delaney clause to reflect the latest scientific and medical knowledge. It would make sense for the law to apply “ equally to cancer-causing and non-cancer-causing substances,” the GAO said.
Other items that contain red dye No. 3: Del Monte fruit cocktail, Signature Select Jordan almonds, Betty Crocker Suddenly! pasta salad, and Jack Links beef stick and cheese. (Christina House / Los Angeles Times)
California has banned all uses of red dye No. 3 in the Golden State, and prohibited the use of six other dyes in foods served or sold in schools. Scientists who examined the dyes for the California Office of Environmental Health Hazard Assessment determined that “the behavioral factors are more of a concern” than the cancer risk, said Asa Bradman, an expert on exposure assessment and epidemiology at UC Merced and co-author of the comprehensive state report.
The FDA has studied the behavioral risks of color additives and hasn’t found “a clear and causal link,” an FDA spokesperson told The Times. Studies suggest some children with behavioral challenges like ADHD appear to be sensitive to food dyes, and that genetic variants affecting the body’s ability to break down histamine are a likely cause. In the FDA’s view, that doesn’t mean the dyes themselves are “neurotoxic,” the spokesperson said.
If there was convincing evidence that an artificial dye failed to meet FDA’s safety standards, the agency would take action whether the health threats were covered by the Delaney clause or not, the spokesperson added.
Mitchell, who worked on the California report with Bradman, said that because manufacturers have been phasing out red dye No. 3 for more than a decade, it’s not a significant concern for her. She’s more worried about the hyperactivity risk posed by red dye No. 40 because it’s ubiquitous in processed foods, especially those consumed by children.
“I’m grateful for the Delaney clause because I do think it’s been very helpful in trying to protect our food,” Mitchell said. “But it doesn’t go far enough. So much of this needs to be revisited.”
Science
California’s summer COVID wave shows signs of waning. What are the numbers in your community?
There are some encouraging signs that California’s summer COVID wave might be leveling off.
That’s not to say the seasonal spike is in the rearview mirror just yet, however. Coronavirus levels in California’s wastewater remain “very high,” according to the U.S. Centers for Disease Control and Prevention, as they are in much of the country.
But while some COVID indicators are rising in the Golden State, others are starting to fall — a hint that the summer wave may soon start to decline.
Statewide, the rate at which coronavirus lab tests are coming back positive was 11.72% for the week that ended Sept. 6, the highest so far this season, and up from 10.8% the prior week. Still, viral levels in wastewater are significantly lower than during last summer’s peak.
The latest COVID hospital admission rate was 3.9 hospitalizations for every 100,000 residents. That’s a slight decline from 4.14 the prior week. Overall, COVID hospitalizations remain low statewide, particularly compared with earlier surges.
The number of newly admitted COVID hospital patients has declined slightly in Los Angeles County and Santa Clara County, but ticked up slightly up in Orange County. In San Francisco, some doctors believe the summer COVID wave is cresting.
“There are a few more people in the hospitals, but I think it’s less than last summer,” said Dr. Peter Chin-Hong, a UC San Francisco infectious diseases expert. “I feel like we are at a plateau.”
Those who are being hospitalized tend to be older people who didn’t get immunized against COVID within the last year, Chin-Hong said, and some have a secondary infection known as superimposed bacterial pneumonia.
Los Angeles County
In L.A. County, there are hints that COVID activity is either peaking or starting to decline. Viral levels in local wastewater are still rising, but the test positivity rate is declining.
For the week that ended Sept. 6, 12.2% of wastewater samples tested for COVID in the county were positive, down from 15.9% the prior week.
“Many indicators of COVID-19 activity in L.A. County declined in this week’s data,” the L.A. County Department of Public Health told The Times on Friday. “While it’s too early to know if we have passed the summer peak of COVID-19 activity this season, this suggests community transmission is slowing.”
Orange County
In Orange County, “we appear to be in the middle of a wave right now,” said Dr. Christopher Zimmerman, deputy medical director of the county’s Communicable Disease Control Division.
The test positivity rate has plateaued in recent weeks — it was 15.3% for the week that ended Sept. 6, up from 12.9% the prior week, but down from 17.9% the week before that.
COVID is still prompting people to seek urgent medical care, however. Countywide, 2.9% of emergency room visits were for COVID-like illness for the week that ended Sept. 6, the highest level this year, and up from 2.6% for the week that ended Aug. 30.
San Diego County
For the week that ended Sept. 6, 14.1% of coronavirus lab tests in San Diego County were positive for infection. That’s down from 15.5% the prior week, and 16.1% for the week that ended Aug. 23.
Ventura County
COVID is also still sending people to the emergency room in Ventura County. Countywide, 1.73% of ER patients for the week that ended Sept. 12 were there to seek treatment for COVID, up from 1.46% the prior week.
San Francisco
In San Francisco, the test positivity rate was 7.5% for the week that ended Sept. 7, down from 8.4% for the week that ended Aug. 31.
“COVID-19 activity in San Francisco remains elevated, but not as high as the previous summer’s peaks,” the local Department of Public Health said.
Silicon Valley
In Santa Clara County, the coronavirus remains at a “high” level in the sewershed of San José and Palo Alto.
Roughly 1.3% of ER visits for the week that ended Sunday were attributed to COVID in Santa Clara County, down from the prior week’s figure of 2%.
Science
Early adopters of ‘zone zero’ fared better in L.A. County fires, insurance-backed investigation finds
As the Eaton and Palisades fires rapidly jumped between tightly packed houses, the proactive steps some residents took to retrofit their homes with fire-resistant building materials and to clear flammable brush became a significant indicator of a home’s fate.
Early adopters who cleared vegetation and flammable materials within the first five feet of their houses’ walls — in line with draft rules for the state’s hotly debated “zone zero” regulations — fared better than those who didn’t, an on-the-ground investigation from the Insurance Institute for Business and Home Safety published Wednesday found.
Over a week in January, while the fires were still burning, the insurance team inspected more than 250 damaged, destroyed and unscathed homes in Altadena and Pacific Palisades.
On properties where the majority of zone zero land was covered in vegetation and flammable materials, the fires destroyed 27% of homes; On properties with less than a quarter of zone zero covered, only 9% were destroyed.
The Insurance Institute for Business and Home Safety, an independent research nonprofit funded by the insurance industry, performed similar investigations for Colorado’s 2012 Waldo Canyon fire, Hawaii’s 2023 Lahaina fire and California’s Tubbs, Camp and Woolsey fires of 2017 and 2018.
While a handful of recent studies have found homes with sparse vegetation in zone zero were more likely to survive fires, skeptics say it does not yet amount to a scientific consensus.
Travis Longcore, senior associate director and an adjunct professor at the UCLA Institute of the Environment and Sustainability, cautioned that the insurance nonprofit’s results are only exploratory: The team did not analyze whether other factors, such as the age of the homes, were influencing their zone zero analysis, and how the nonprofit characterizes zone zero for its report, he noted, does not exactly mirror California’s draft regulations.
Meanwhile, Michael Gollner, an associate professor of mechanical engineering at UC Berkeley who studies how wildfires destroy and damage homes, noted that the nonprofit’s sample does not perfectly represent the entire burn areas, since the group focused specifically on damaged properties and were constrained by the active firefight.
Nonetheless, the nonprofit’s findings help tie together growing evidence of zone zero’s effectiveness from tests in the lab — aimed at identifying the pathways fire can use to enter a home — with the real-world analyses of which measures protected homes in wildfires, Gollner said.
A recent study from Gollner looking at more than 47,000 structures in five major California fires (which did not include the Eaton and Palisades fires) found that of the properties that removed vegetation from zone zero, 37% survived, compared with 20% that did not.
Once a fire spills from the wildlands into an urban area, homes become the primary fuel. When a home catches fire, it increases the chance nearby homes burn, too. That is especially true when homes are tightly packed.
When looking at California Department of Forestry and Fire Protection data for the entirety of the two fires, the insurance team found that “hardened” homes in Altadena and the Palisades that had noncombustable roofs, fire-resistant siding, double-pane windows and closed eaves survived undamaged at least 66% of the time, if they were at least 20 feet away from other structures.
But when the distance was less than 10 feet, only 45% of the hardened homes escaped with no damage.
“The spacing between structures, it’s the most definitive way to differentiate what survives and what doesn’t,” said Roy Wright, president and chief executive of the Insurance Institute for Business and Home Safety. At the same time, said Wright, “it’s not feasible to change that.”
Looking at steps that residents are more likely to be able to take, the insurance nonprofit found that the best approach is for homeowners to apply however many home hardening and defensible space measures that they can. Each one can shave a few percentage points off the risk of a home burning, and combined, the effect can be significant.
As for zone zero, the insurance team found a number of examples of how vegetation and flammable materials near a home could aid the destruction of a property.
At one home, embers appeared to have ignited some hedges a few feet away from the structure. That heat was enough to shatter a single pane window, creating the perfect opportunity for embers to enter and burn the house from the inside out. It miraculously survived.
At others, embers from the blazes landed on trash and recycling bins close to the houses, sometimes burning holes through the plastic lids and igniting the material inside. In one instance, the fire in the bin spread to a nearby garage door, but the house was spared.
Wooden decks and fences were also common accomplices that helped embers ignite a structure.
California’s current zone zero draft regulations take some of those risks into account. They prohibit wooden fences within the first five feet of a home; the state’s zone zero committee is also considering whether to prohibit virtually all vegetation in the zone or to just limit it (regardless, well-maintained trees are allowed).
On the other hand, the draft regulations do not prohibit keeping trash bins in the zone, which the committee determined would be difficult to enforce. They also do not mandate homeowners replace wooden decks.
The controversy around the draft regulations center around the proposal to remove virtually all healthy vegetation, including shrubs and grasses, from the zone.
Critics argue that, given the financial burden zone zero would place on homeowners, the state should instead focus on measures with lower costs and a significant proven benefit.
“A focus on vegetation is misguided,” said David Lefkowith, president of the Mandeville Canyon Assn.
At its most recent zone zero meeting, the Board of Forestry and Fire Protection directed staff to further research the draft regulations’ affordability.
“As the Board and subcommittee consider which set of options best balance safety, urgency, and public feasibility, we are also shifting our focus to implementation and looking to state leaders to identify resources for delivering on this first-in-the-nation regulation,” Tony Andersen, executive officer of the board, said in a statement. “The need is urgent, but we also want to invest the time necessary to get this right.”
Home hardening and defensible space are just two of many strategies used to protect lives and property. The insurance team suspects that many of the close calls they studied in the field — homes that almost burned but didn’t — ultimately survived thanks to firefighters who stepped in. Wildfire experts also recommend programs to prevent ignitions in the first place and to manage wildlands to prevent intense spread of a fire that does ignite.
For Wright, the report is a reminder of the importance of community. The fate of any individual home is tied to that of those nearby — it takes a whole neighborhood hardening their homes and maintaining their lawns to reach herd immunity protection against fire’s contagious spread.
“When there is collective action, it changes the outcomes,” Wright said. “Wildfire is insidious. It doesn’t stop at the fence line.”
Science
Notorious ‘winter vomiting bug’ rising in California. A new norovirus strain could make it worse
The dreaded norovirus — the “vomiting bug” that often causes stomach flu symptoms — is climbing again in California, and doctors warn that a new subvariant could make even more people sick this season.
In L.A. County, concentrations of norovirus are already on the rise in wastewater, indicating increased circulation of the disease, the local Department of Public Health told the Los Angeles Times.
Norovirus levels are increasing across California, and the rise is especially notable in the San Francisco Bay Area and L.A., according to the California Department of Public Health.
And the rate at which norovirus tests are confirming infection is rising nationally and in the Western U.S. For the week that ended Nov. 22, the test positivity rate nationally was 11.69%, up from 8.66% two months earlier. In the West, it was even worse: 14.08%, up from 9.59%, according to the U.S. Centers for Disease Control and Prevention.
Norovirus is extraordinarily contagious, and is America’s leading cause of vomiting and diarrhea, according to the CDC. Outbreaks typically happen in the cooler months between November and April.
Clouding the picture is the recent emergence of a new norovirus strain — GII.17. Such a development can result in 50% more norovirus illness than typical, the CDC says.
“If your immune system isn’t used to something that comes around, a lot of people get infected,” said Dr. Peter Chin-Hong, an infectious diseases expert at UC San Francisco.
During the 2024-25 winter season, GII.17 overthrew the previous dominant norovirus strain, GII.4, that had been responsible for more than half of national norovirus outbreaks over the preceding decade. The ancestor of the GII.17 strain probably came from a subvariant that triggered an outbreak in Romania in 2021, according to CDC scientists.
GII.17 vaulted in prominence during last winter’s norovirus surge and was ultimately responsible for about 75% of outbreaks of the disease nationally.
The strain’s emergence coincided with a particularly bad year for norovirus, one that started unusually early in October 2024, peaked earlier than normal the following January and stretched into the summer, according to CDC scientists writing in the journal Emerging Infectious Diseases.
During the three prior seasons, when GII.4 was dominant, norovirus activity had been relatively stable, Chin-Hong said.
Norovirus can cause substantial disruptions — as many parents know all too well. An elementary school in Massachusetts was forced to cancel all classes on Thursday and Friday because of the “high volume of stomach illness cases,” which was suspected to be driven by norovirus.
More than 130 students at Roberts Elementary School in Medford, Mass., were absent Wednesday, and administrators said there probably wouldn’t be a “reasonable number of students and staff” to resume classes Friday. A company was hired to perform a deep clean of the school’s classrooms, doorknobs and kitchen equipment.
Some places in California, however, aren’t seeing major norovirus activity so far this season. Statewide, while norovirus levels in wastewater are increasing, they still remain low, the California Department of Public Health said.
There have been 32 lab-confirmed norovirus outbreaks reported to the California Department of Public Health so far this year. Last year, there were 69.
Officials caution the numbers don’t necessarily reflect how bad norovirus is in a particular year, as many outbreaks are not lab-confirmed, and an outbreak can affect either a small or large number of people.
Between Aug. 1 and Nov. 13, there were 153 norovirus outbreaks publicly reported nationally, according to the CDC. During the same period last year, there were 235.
UCLA hasn’t reported an increase in the number of norovirus tests ordered, nor has it seen a significant increase in test positivity rates. Chin-Hong said he likewise hasn’t seen a big increase at UC San Francisco.
“Things are relatively still stable clinically in California, but I think it’s just some amount of time before it comes here,” Chin-Hong said.
In a typical year, norovirus causes 2.27 million outpatient clinic visits, mostly young children; 465,000 emergency department visits, 109,000 hospitalizations, and 900 deaths, mostly among seniors age 65 and older.
People with severe ongoing vomiting, profound diarrhea and dehydration may need to seek medical attention to get hydration intravenously.
“Children who are dehydrated may cry with few or no tears and be unusually sleepy or fussy,” the CDC says. Sports drinks can help with mild dehydration, but what may be more helpful are oral rehydration fluids that can be bought over the counter.
Children under the age of 5 and adults 85 and older are most likely to need to visit an emergency room or clinic because of norovirus, and should not hesitate to seek care, experts say.
“Everyone’s at risk, but the people who you worry about, the ones that we see in the hospital, are the very young and very old,” Chin-Hong said.
Those at highest risk are babies, because it doesn’t take much to cause potentially serious problems. Newborns are at risk for necrotizing enterocolitis, a life-threatening inflammation of the intestine that virtually only affects new babies, according to the National Library of Medicine.
Whereas healthy people generally clear the virus in one to three days, immune-compromised individuals can continue to have diarrhea for a long time “because their body’s immune system can’t neutralize the virus as effectively,” Chin-Hong said.
The main way people get norovirus is by accidentally drinking water or eating food contaminated with fecal matter, or touching a contaminated surface and then placing their fingers in their mouths.
People usually develop symptoms 12 to 48 hours after they’re exposed to the virus.
Hand sanitizer does not work well against norovirus — meaning that proper handwashing is vital, experts say.
People should lather their hands with soap and scrub for at least 20 seconds, including the back of their hands, between their fingers and under their nails, before rinsing and drying, the CDC says.
One helpful way to keep track of time is to hum the “Happy Birthday” song from beginning to end twice, the CDC says. Chin-Hong says his favorite is the chorus of Kelly Clarkson’s “Since U Been Gone.”
If you’re living with someone with norovirus, “you really have to clean surfaces and stuff if they’re touching it,” Chin-Hong said. Contamination is shockingly easy. Even just breathing out little saliva droplets on food that is later consumed by someone else can spread infection.
Throw out food that might be contaminated with norovirus, the CDC says. Noroviruses are relatively resistant to heat and can survive temperatures as high as 145 degrees.
Norovirus is so contagious that even just 10 viral particles are enough to cause infection. By contrast, it takes ingesting thousands of salmonella particles to get sick from that bacterium.
People are most contagious when they are sick with norovirus — but they can still be infectious even after they feel better, the CDC says.
The CDC advises staying home for 48 hours after infection. Some studies have even shown that “you can still spread norovirus for two weeks or more after you feel better,” according to the CDC.
The CDC also recommends washing laundry in hot water.
Besides schools, other places where norovirus can spread quickly are cruise ships, day-care centers and prisons, Chin-Hong said.
The most recent 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 2,007 passengers on board, 4.8% have reported being ill. The outbreak was first reported on Nov. 30 following stops that month at the Isle of Portland, England; Halifax, Canada; Boston; New York City; Charleston, S.C.; and Miami.
According 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.
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