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New genetic research points to Wuhan animal market as origin of COVID pandemic, study says

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New genetic research points to Wuhan animal market as origin of COVID pandemic, study says

A new analysis of genetic material gathered from a live-animal market in Wuhan in the early weeks of the COVID-19 pandemic strengthens the case that the outbreak originated there when the coronavirus jumped from infected animals to humans, scientists said.

The findings, reported the journal Cell, do not identify any specific infected animal that brought the SARS-CoV-2 virus to a Chinese city inhabited by more than 11 million people. Nor do they definitively prove that the Huanan Seafood Wholesale Market was Ground Zero for a pandemic that has resulted in more than 7 million deaths.

But the genetic evidence shows the market met the conditions necessary to spark an outbreak and makes it increasingly difficult to explain how the coronavirus could have emerged from a laboratory, a farm or even from another of the city’s four live-animal markets, the study authors said.

“It’s like if a gorilla virus emerged in San Diego and first hit people who worked at the San Diego Zoo and lived nearby, then spread later more widely,” said Michael Worobey, an evolutionary biologist at the University of Arizona who worked on the study. “It would not be difficult to reason that it very likely came from the gorillas at the zoo.”

The root cause of the pandemic has been hotly debated since its early days. Wuhan is home to a government laboratory where scientists study coronaviruses similar to SARS-CoV-2, a fact that prompted politicians, national security experts, late-night talk show hosts and many scientists — including Worobey — to question whether the virus had leaked from the lab.

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Compelling though the argument may be, hard evidence to support the leak hypothesis has been lacking. Meanwhile, more information has come to light that has persuaded scientists with expertise in relevant fields that the virus that causes COVID-19 originated in animals, just like the viruses that cause SARS, MERS and influenza.

The new results continue that trend, said Dr. Dominic Dwyer, a member of the international task force that investigated the pandemic’s origins for the World Health Organization.

“You put all of these origin hypotheses on the table, and then some of them become stronger as you get evidence,” said Dwyer, a medical virologist at the University of Sydney and Westmead Hospital in Australia who wasn’t involved in the latest work. “This paper has more evidence that supports the animal origin through the Huanan market.”

The analysis published Thursday was based on genetic data gleaned from hundreds of samples gathered in and around the Huanan market collected by researchers from the Chinese Center for Disease Control and Prevention soon after the market was shut down on Jan. 1, 2020. The Chinese team detected the coronavirus in 74 of the environmental samples they tested, according to their report last year in the journal Nature.

Worobey and his colleagues dug deeper into that data. Using two distinct gene-sequencing techniques, they looked for pieces of SARS-CoV-2 as well as for DNA from animals and people.

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Then they plotted what they found on a map of the sprawling market, allowing the team to reconstruct how a few initial infections could have ballooned into a global health emergency.

Among 585 samples gathered in early January 2020, the ones that contained the coronavirus were clustered in the southwestern section of the market. That happened to be the area where wild animals were held in cages for sale.

“The market covers a couple of acres, and this comes down to one corner of the market, and to a couple of stalls,” Dwyer said. “That fits with an animal origin. If it was coming from people wandering around the market, you’d find it everywhere.”

One market stall “stood out,” the study authors wrote. It had evidence of SARS-CoV-2 in multiple places: on at least one cart, on an iron container, on the ground, and on a machine used to remove hair and feathers. The researchers dubbed it “wildlife stall A.”

Another 60 samples were taken from the market’s drainage system at the end of January 2020. The researchers found genetic evidence of the coronavirus in four of them, including one in front of wildlife stall A.

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That drain was still testing positive for SARS-CoV-2 in mid-February. So were two drains downstream from it that could have been contaminated by runoff from wildlife stall A, the researchers wrote.

The samples from the stall that contained the coronavirus also contained DNA from a variety of animals, including dogs, rabbits, hoary bamboo rats, Malayan porcupines and masked palm civets. The most abundant DNA was from raccoon dogs, and some was detected in a nearby garbage cart that also tested positive for the virus.

The closest-known relatives to SARS-CoV-2 that exist in the wild are coronaviruses that circulate in horseshoe bats in southern China, Laos and Vietnam and in pangolins from southern China. But no DNA from bats or pangolins turned up in any of the Huanan market samples.

Raccoon dogs, masked palm civets, hoary bamboo rats and Malayan porcupines have transmitted bat coronaviruses before, the study authors noted. Could they have done so in Wuhan, they wondered?

Security guards stand in front of the closed Huanan Seafood Wholesale Market in Wuhan on Jan. 11, 2020.

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(Noel Celis / AFP via Getty Images)

It is unclear whether bamboo rats or Malayan porcupines can be infected with SARS-CoV-2, the study authors wrote. There is no hard evidence that masked palm civets can catch the virus, but cell lines from the animals were susceptible in laboratory experiments.

Raccoon dogs, on the other hand, are known to catch and transmit SARS-CoV-2. And they were the most abundant animal in wildlife stall A.

The researchers dug into the raccoon dog DNA to see if they could have come from southern China, where they might have crossed paths with bats. They couldn’t tell, but they were able to rule out a connection to raccoon dogs that lived on fur farms in northern China.

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Worobey and his colleagues also studied non-SARS-CoV-2 animal viruses that were detected in wildlife stalls to see if they offered clues about where the infected animals had come from.

A kobuvirus that infected civets in the Huanan market was closely related to a virus detected in animals sold in Sichuan and Guangxi provinces, which are closer to the territory of horseshoe bats and pangolins. And a betacoronavirus that infected bamboo rats had a close relative on a bamboo rat farm in Guangxi, one of two southern provinces where market vendors were known to have sourced the animals.

“These findings suggest some movement of infected animals from southern China to Wuhan, a trade conduit that could have also led to the emergence of SARS-CoV-2,” the study authors wrote.

Nailing this down will require more sleuthing, including field work to collect samples from animals in China, said Florence Débarre, an evolutionary biologist at the French National Centre for Scientific Research in Paris and the study’s senior author. Worobey said he plans to continue this line of inquiry.

Dwyer praised the effort to determine where the animals in the market had come from — and by extension, how the virus could have gotten to the market.

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A second line of evidence also supports the hypothesis that the pandemic had a so-called zoonotic origin, scientists said.

Among the samples collected at the Huanan market on Jan. 1, 2020, the researchers were able to identify four nearly complete SARS-CoV-2 genomes. One of them was from so-called lineage A, and the other three were from the closely related lineage B.

The researchers weren’t able to tell whether those viruses were shed by animals or people, but the lineage A sample came from a stall where a worker sought medical attention in mid-December 2019. Although that was weeks before COVID-19 had been recognized as a disease, a report from the World Health Organization later described the worker as a suspected early patient.

Confirming the presence of both lineages in the market allowed the team to compare their genomes and work backward to figure out when the two strains diverged, and what their most recent common ancestor looked like. They came up with six candidates, some of them more plausible than others.

There was a 99% probability that one of the four most likely candidates was correct, and those four all had something important in common: They were “equivalent or identical” to the most recent common ancestor for the pandemic as a whole, said study leader Alexander Crits-Christoph, an independent computational microbiologist.

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That’s what they would expect to find if the outbreak began at the Huanan market, the study authors said. In that scenario, an animal or animals infected with the virus arrived at the market in November or early December. The virus then spread among animals held in close quarters indoors, as well as to their human handlers. Those conditions would have given the virus the multiple chances it needed to establish itself in people and begin spreading among its new hosts in a densely populated city.

On the other hand, it’s getting more difficult to fit all of this evidence into a coherent story that has the coronavirus entering China via imported frozen food (as the Chinese government has claimed) or escaping from a virology lab with lax biosecurity protocols (as some members of the U.S. intelligence community have proposed), Dwyer said.

“We’ve had nothing added to support the lab leak or the frozen food theories,” he said. “It just continues to strengthen the animal and market hypothesis.”

Considering that the pandemic began in a city with a virology lab where scientists study coronaviruses, it makes sense to ask whether that’s more than a coincidence and to wonder whether incriminating evidence is being covered up, DéBarre said.

“Many of us were extremely open to this idea,” she said. “But then data have accumulated, and they all go in the same direction — they all point to the market.”

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“In science you very rarely have final answers,” she added. “You say, ‘Given all the data we have, this looks like the most likely interpretation.’”

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Can fire-resistant homes be sexy? ‘You be the judge,’ says this Palisades architect

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Can fire-resistant homes be sexy? ‘You be the judge,’ says this Palisades architect

At first glance, it looks like nothing more than a charming Spanish-revival, quintessentially Californian home — but this Pacific Palisades rebuild is constructed like a tank.

Every exterior wall of the steel-framed home is a foot-thick, fire-resistant barricade. The home is connected to a satellite fire monitoring service. Should a fire start in town, sturdy metal shutters descend to cover every window. An exterior sprinkler system can pump 40,000 gallons of water from giant tanks hidden behind the shrubs in the property’s yard. If the cameras and heat sensors around the house detect danger, the system can envelop the home in over 1,000 gallons of fire retardant and hundreds of gallons of fire-suppressing foam.

Palisades resident and architect Ardie Tavangarian is so confident in his design that he even asked the fire department if they could start a controlled fire on the property to test it all out. (They said no.)

Tavangarian built a career designing multimillion-dollar luxury homes in Los Angeles, but after the Palisades fire destroyed 13 of his works — including his family’s home — he found another calling: how to design a house that can handle what the Santa Monica Mountains throw at it. And how to do it quickly and affordably.

Water tanks form part of a backup water supply in a newly built fire-resistant home in Pacific Palisades.

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“Nature is so powerful,” he said, sitting on a couch in the new house, which he built for his adult twin daughters. “We are guests living in that environment and expecting, ‘Oh, nature is going to be really kind to me.’ No, it’s not. It does what it’s supposed to do.”

Tavangarian watched the Jan. 1 Lachman fire from his property not far from here; a week later that fire rekindled, grew into the Palisades fire, and burned through his house. But the painful details of the fire — the missteps of the fire department, the empty reservoir — didn’t matter when it came to deciding how to rebuild, he said. The reality is, many fires have burned in these mountains. Many more will.

A sprinkler on a roof.

A sprinkler on the roof is part of a house-wide sprinkler system.

For the architect, who has spent much of his 45-year career designing for luxury, hardening a home against wildfire has brought a new kind of luxury to his homes: peace of mind.

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It’s a sentiment that resonates with fire survivors: Tavangarian says he’s received considerable interest from other property owners in the Palisades looking to rebuild their houses.

The metal shutters and advanced outdoor sprinkler system are the flashiest parts of Tavangarian’s home hardening project, and the efficacy of these adaptations is still up for debate. Because the measures have not yet been widely adopted, there are few studies exploring how much or little they protect homes in real-world fires.

Ardie Tavangarian stands inside a house.

Architect Ardie Tavangarian inside the house he designed.

Anecdotal evidence has indicated the effectiveness of sprinklers can vary significantly based on the setup and the conditions during the fire. Extreme wind, for example, can make them less effective. Lab studies have generally found shutters can reduce the risk of windows shattering.

These measures aren’t cheap, either. Sprinkler systems can cost north of $100,000, for example. However, Tavangarian said when all was said and done, the home he built for his daughters cost around $700 per square foot — less than what Palisades residents said they expected to pay, but more than what Altadena residents expected for their rebuilds.

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Tavangarian also hopes to see insurers increasingly consider the home-hardening measures property owners take when writing policies, which he said could potentially offset the extra cost in a decade or less. As he explored getting insurance for the new home, one insurer quoted him $80,000 a year. After he convinced the company to visit the property, it lowered the quote to just $13,000, he said.

A living room inside a fire-resistant house, with metal heat shields drawn over the windows.

The house includes metal heat shields that can drop down if a fire approaches.

The home also has essentially all of the other less flashy — but much cheaper and well-proven — home hardening measures recommended by fire professionals: The underside of the roof’s overhang is closed off — a common place embers enter a home. The roof, where burning embers can accumulate, is made of fire-resistant material. The windows, vulnerable to shattering in extreme heat, are made of a toughened glass. There is virtually no vegetation within the first five feet of the home.

When asked if he felt he had compromised on design, comfort or aesthetics for the extra protection — one of the many concerns Californians have with the state’s draft “Zone Zero” requirements that may significantly limit vegetation within five feet of a home — Tavangarian simply said, “You be the judge.”

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Commentary: My toothache led to a painful discovery: The dental care system is full of cavities as you age

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Commentary: My toothache led to a painful discovery: The dental care system is full of cavities as you age

I had a nagging toothache recently, and it led to an even more painful revelation.

If you X-rayed the state of oral health care in the United States, particularly for people 65 and older, the picture would be full of cavities.

“It’s probably worse than you can even imagine,” said Elizabeth Mertz, a UC San Francisco professor and Healthforce Center researcher who studies barriers to dental care for seniors.

Mertz once referred to the snaggletoothed, gap-filled oral health care system — which isn’t really a system at all — as “a mess.”

But let me get back to my toothache, while I reach for some painkiller. It had been bothering me for a couple of weeks, so I went to see my dentist, hoping for the best and preparing for the worst, having had two extractions in less than two years.

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Let’s make it a trifecta.

My dentist said a molar needed to be yanked because of a cellular breakdown called resorption, and a periodontist in his office recommended a bone graft and probably an implant. The whole process would take several months and cost roughly the price of a swell vacation.

I’m lucky to have a great dentist and dental coverage through my employer, but as anyone with a private plan knows, dental insurance can barely be called insurance. It’s fine for cleanings and basic preventive routines. But for more complicated and expensive procedures — which multiply as you age — you can be on the hook for half the cost, if you’re covered at all, with annual payout caps in the $1,500 range.

“The No. 1 reason for delayed dental care,” said Mertz, “is out-of-pocket costs.”

So I wondered if cost-wise, it would be better to dump my medical and dental coverage and switch to a Medicare plan that costs extra — Medicare Advantage — but includes dental care options. Almost in unison, my two dentists advised against that because Medicare supplemental plans can be so limited.

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Sorting it all out can be confusing and time-consuming, and nobody warns you in advance that aging itself is a job, the benefits are lousy, and the specialty care you’ll need most — dental, vision, hearing and long-term care — are not covered in the basic package. It’s as if Medicare was designed by pranksters, and we’re paying the price now as the percentage of the 65-and-up population explodes.

So what are people supposed to do as they get older and their teeth get looser?

A retired friend told me that she and her husband don’t have dental insurance because it costs too much and covers too little, and it turns out they’re not alone. By some estimates, half of U.S. residents 65 and older have no dental insurance.

That’s actually not a bad option, said Mertz, given the cost of insurance premiums and co-pays, along with the caps. And even if you’ve got insurance, a lot of dentists don’t accept it because the reimbursements have stagnated as their costs have spiked.

But without insurance, a lot of people simply don’t go to the dentist until they have to, and that can be dangerous.

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“Dental problems are very clearly associated with diabetes,” as well as heart problems and other health issues, said Paul Glassman, associate dean of the California Northstate University dentistry school.

There is one other option, and Mertz referred to it as dental tourism, saying that Mexico and Costa Rica are popular destinations for U.S. residents.

“You can get a week’s vacation and dental work and still come out ahead of what you’d be paying in the U.S.,” she said.

Tijuana dentist Dr. Oscar Ceballos told me that roughly 80% of his patients are from north of the border, and come from as far away as Florida, Wisconsin and Alaska. He has patients in their 80s and 90s who have been returning for years because in the U.S. their insurance was expensive, the coverage was limited and out-of-pocket expenses were unaffordable.

“For example, a dental implant in California is around $3,000-$5,000,” Ceballos said. At his office, depending on the specifics, the same service “is like $1,500 to $2,500.” The cost is lower because personnel, office rent and other overhead costs are cheaper than in the U.S., Ceballos said.

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As we spoke by phone, Ceballos peeked into his waiting room and said three patients were from the U.S. He handed his cellphone to one of them, San Diegan John Lane, who said he’s been going south of the border for nine years.

“The primary reason is the quality of the care,” said Lane, who told me he refers to himself as 39, “with almost 40 years of additional” time on the clock.

Ceballos is “conscientious and he has facilities that are as clean and sterile and as medically up to date as anything you’d find in the U.S.,” said Lane, who had driven his wife down from San Diego for a new crown.

“The cost is 50% less than what it would be in the U.S.,” said Lane, and sometimes the savings is even greater than that.

Come this summer, Lane may be seeing even more Californians in Ceballos’ waiting room.

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“Proposed funding cuts to the Medi-Cal Dental program would have devastating impacts on our state’s most vulnerable residents,” said dentist Robert Hanlon, president of the California Dental Assn.

Dental student Somkene Okwuego smiles after completing her work on patient Jimmy Stewart, 83, who receives affordable dental work at the Ostrow School of Dentistry of USC on the USC campus in Los Angeles on February 26, 2026.

(Genaro Molina / Los Angeles Times)

Under Proposition 56’s tobacco tax in 2016, supplemental reimbursements to dentists have been in place, but those increases could be wiped out under a budget-cutting proposal. Only about 40% of the state’s dentists accept Medi-Cal payments as it is, and Hanlon told me a CDA survey indicates that half would stop accepting Medi-Cal patients and many others will accept fewer patients.

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“It’s appalling that when the cost of providing healthcare is at an all-time high, the state is considering cutting program funding back to 1990s levels,” Hanlon said. “These cuts … will force patients to forgo or delay basic dental care, driving completely preventable emergencies into already overcrowded emergency departments.”

Somkene Okwuego, who as a child in South L.A. was occasionally a patient at USC’s Herman Ostrow School of Dentistry clinic, will graduate from the school in just a few months.

I first wrote about Okwuego three years ago, after she got an undergrad degree in gerontology, and she told me a few days ago that many of her dental patients are elderly and have Medi-Cal or no insurance at all. She has also worked at a Skid Row dental clinic, and plans after graduation to work at a clinic where dental care is free or discounted.

Okwuego said “fixing the smiles” of her patients is a privilege and boosts their self-image, which can help “when they’re trying to get jobs.” When I dropped by to see her Thursday, she was with 83-year-old patient Jimmy Stewart.

Stewart, an Army veteran, told me he had trouble getting dental care at the VA and had gone years without seeing a dentist before a friend recommended the Ostrow clinic. He said he’s had extractions and top-quality restorative care at USC, with the work covered by his Medi-Cal insurance.

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I told Stewart there could be some Medi-Cal cuts in the works this summer.

“I’d be screwed,” he said.

Him and a lot of other people.

steve.lopez@latimes.com

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Diablo Canyon clears last California permit hurdle to keep running

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Diablo Canyon clears last California permit hurdle to keep running

Central Coast Water authorities approved waste discharge permits for Diablo Canyon nuclear plant Thursday, making it nearly certain it will remain running through 2030, and potentially through 2045.

The Pacific Gas & Electric-owned plant was originally supposed to shut down in 2025, but lawmakers extended that deadline by five years in 2022, fearing power shortages if a plant that provides about 9 percent the state’s electricity were to shut off.

In December, Diablo Canyon received a key permit from the California Coastal Commission through an agreement that involved PG&E giving up about 12,000 acres of nearby land for conservation in exchange for the loss of marine life caused by the plant’s operations.

Today’s 6-0 vote by the Central Coast Regional Water Board approved PG&E’s plans to limit discharges of pollutants into the water and continue to run its “once-through cooling system.” The cooling technology flushes ocean water through the plant to absorb heat and discharges it, killing what the Coastal Commission estimated to be two billion fish each year.

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The board also granted the plant a certification under the Clean Water Act, the last state regulatory hurdle the facility needed to clear before the federal Nuclear Regulatory Commission (NRC) is allowed to renew its permit through 2045.

The new regional water board permit made several changes since the last one was issued in 1990. One was a first-time limit on the chemical tributyltin-10, a toxic, internationally-banned compound added to paint to prevent organisms from growing on ship hulls.

Additional changes stemmed from a 2025 Supreme Court ruling that said if pollutant permits like this one impose specific water quality requirements, they must also specify how to meet them.

The plant’s biggest water quality impact is the heated water it discharges into the ocean, and that part of the permit remains unchanged. Radioactive waste from the plant is regulated not by the state but by the NRC.

California state law only allows the plant to remain open to 2030, but some lawmakers and regulators have already expressed interest in another extension given growing electricity demand and the plant’s role in providing carbon-free power to the grid.

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Some board members raised concerns about granting a certification that would allow the NRC to reauthorize the plant’s permits through 2045.

“There’s every reason to think the California entities responsible for making the decision about continuing operation, namely the California [Independent System Operator] and the Energy Commission, all of them are sort of leaning toward continuing to operate this facility,” said boardmember Dominic Roques. “I’d like us to be consistent with state law at least, and imply that we are consistent with ending operation at five years.”

Other board members noted that regulators could revisit the permits in five years or sooner if state and federal laws changes, and the board ultimately approved the permit.

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