Latest news with #RichardWebby
Scientific American
05-08-2025
- Health
- Scientific American
Bird Flu on Dairy Farms May Be Airborne After All
The H5N1 avian influenza virus can now be found not only in milk and on milking equipment but also in farm wastewater and in the air, say researchers who have been trying to figure out how the virus spreads on dairy farms. The researchers identified the virus in both large and small aerosol particles in the air on farms affected by bird flu in California, according to a new preprint paper posted on the biology server bioRxiv. 'There is a lot of H5N1 virus on these farms,' says Seema Lakdawala, an associate professor of microbiology and immunology at the Emory University School of Medicine and senior author of the new study, which has yet to go through scientific peer review. 'It is everywhere. We need to be expanding biosafety measures, biosecurity measures and trying to control where the virus is.' On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. The finding—that the virus is 'everywhere'—fits with what has been seen in previously published work, says Richard Webby, who studies host-microbe interactions at St. Jude Children's Research Hospital. 'It's a ridiculously contaminated environment,' Webby says. The high concentrations of H5N1 in the environment may explain why the virus transmits so readily among cattle on dairy farms, as well as why a study from last fall found that 7 percent of tested dairy farm workers had antibody evidence of a previous bird flu infection. H5N1-infected cattle were first reported in March 2024. Since then the Centers for Disease Control and Prevention has found 41 human cases directly stemming from contact with milking cows. And the disease has spread readily within herds. But exactly how it's spreading has been oddly difficult to pin down. Another recent preprint study by the Ohio State University veterinary medicine professor Andrew Bowman and his colleagues found that, when liquid containing the virus was put into cows' teats, only a very low dose was necessary to cause an infection. But strangely, when the researchers milked the well cows with contaminated equipment—the way the virus was assumed to be spreading on farms—the healthy cows did not fall ill. 'It seems like it shouldn't be that hard to make transmission happen, given the way we see it spread through dairy farms in the field,' said Bowman in an interview with Scientific American in June. Lakdawala and her team wanted to figure out how the virus moves between cows in hopes of finding a way to slow or stop the spread. They began testing affected dairy farms in California in the winter of 2024 and ended up assessing a total of 14 farms by early 2025, a period representing the peak of the dairy cattle outbreak. The researchers used aerosol sampling devices to test both cow exhalations and the ambient air in milking parlors and barns. They also tested milk and the entire wastewater system, from the drains in milking parlors to the manure lagoons outdoors. The team found plenty of opportunities for the virus to transmit, given that viral particles were found all over. 'It's not a single event or a single thing that drives transmission,' Lakdawala says. 'The likelihood is: overbombardment of viruses in the environment is leading to efficient transmission. They're inhaling it; they're probably also finding it on their bodies; they're licking it; they're finding it on the milking equipment—all of it together.' The researchers found one sample with mutations in an area on the H5N1 genome that's known to change when avian viruses become more adept at spreading between humans. It's not clear whether that particular mutation would have helped the virus infect humans more effectively. Luckily, that version of the pathogen did not go on to reproduce: it seems to have emerged and, just as quickly, to have died out. Another recent paper, published by Webby and his team in the journal Nature Communications in July, found that, so far, the virus circulating in cattle still looks very much like the virus circulating in birds. That research also found that the bovine virus couldn't spread through the air between ferrets, which are used because they transmit flu viruses much like humans do. 'We've dodged a little bit of a bullet so far with cows and this virus,' Webby says. But with so much virus on affected farms, there's a chance that future human-oriented mutations could arise, Lakdawala warns. She suspects the virus becomes aerosolized during both milking and cleaning. Also, workers often spray down floors and other farm surfaces with wastewater that they now know can contain infected milk. Face shields that can block large droplets and large aerosols without the discomfort of masks might be one way to reduce cow-to-human infections among workers. Rapid 'at-barn' H5N1 tests, not unlike the at-home flu or COVID tests people can purchase at drug stores, would help farmers identify and isolate sick cows before they could infect others, she says. And treating infectious milk before it's dumped—perhaps with a weak acid such as vinegar or lemon juice to inactivate the virus, Lakdawala says—could keep H5N1 out of wastewater. 'This is highlighting to me that we really need to work harder to get this entire outbreak under control,' she says.
Agriland
04-08-2025
- Health
- Agriland
Study: Viruses in cattle more likely to infect birds than humans
Viruses in cows are more similar to viruses in birds than humans. US research has found that H5N1 viruses in dairy cows are more similar to those sampled from birds than influenza viruses that are better at infecting humans. The research from St. Jude Children's Research Hospital revealed that avian influenza (bird flu) from the ongoing outbreak in US dairy cattle appears to be keeping its bird-infecting features, rather than adapting to "better" infect other mammals. Since 2024, when scientists in the Tennessee hospital first detected H5N1 bird flu in dairy cattle, there has been fears that the virus would use cattle as a "bridge" to mutate and gain the ability to infect and spread into humans. Researchers at the hospital tested a panel of these viruses from dairy cows, and found that the viruses had more molecular and biological features in common with avian than human flu viruses. In addition, the viruses from cows could not transmit through the air between mammals, though direct infection of an individual human from close contact with infected dairy cattle is possible. Corresponding author from the St. Jude department of host-microbe interactions, Richard Webby said: "We found that these flu viruses from cow udders are not under a lot of pressure to mutate to better infect other mammals such as humans. "For now, the risk of becoming a pandemic threat to humans appears low, though the risk of direct infection for those working with these animal remains high." While they may not infect humans "efficiently", according to the US researchers, viruses from dairy cows have already caused at least 41 in people through close contact with dairy cattle. The scientists in St. Jude's wanted to know if the viruses could spread between humans, so they studied a mammalian model of human influenza infection. The research found that the models could not pass the bovine flu to each other through the air. However, these models could spread the virus through direct contact. According to St. Jude's, the lack of airborne transmission indicates a low risk of spreading between humans, but the other experiments suggest that there is still a threat of direct infection. As a result, the scientists looked to see if current interventions for flu could help treat such infections. This process began by examining the immune molecules in the blood of people vaccinated against avian influenza. If vaccines fail, then physicians will reach for antivirals to treat an infected individual. According to the hospital, there are two antivirals used in patients with influenza, so the researchers measured how well both controlled H5N1 infections from the cow viruses in the lab, and studied genetic markers of treatment resistance. The researchers explained that while results are encouraging, they do not mean that bovine viruses are "innocuous", and that infected mammalian models still showed signs of sickness, as have some humans. In addition, the virus continues to evolve, so the results from the research may not apply in the future if a new variant arises.
Yahoo
18-04-2025
- Health
- Yahoo
Mexican child infected with H5N1 bird flu dies from respiratory complications
A 3-year-old girl in Mexico died this month after getting infected with H5N1 bird flu, according to a report issued by the World Health Organization this week. Authorities say the strain of bird flu is one that has been circulating in wild birds throughout North America, known as D1.1. It is the same strain implicated in the death of a person in Louisiana earlier this year, and in the case of a 13-year-old Canadian who was placed on life-support for several weeks before recovering. Two others, a person in Wyoming and a poultry worker in Ohio, were also reported to have severe disease after exposure to this strain of the virus. The strain has been detected in dairy herds from Nevada and Arizona. "The case in Mexico is another great reminder of how dangerous H5 viruses can be," said Richard Webby, an infectious disease expert at St. Jude Children's Research Hospital in Memphis, Tenn. The D1.1 strain is widespread in the U.S. and Canada, but until this week's WHO report it was unclear how far south the strain had traveled, he said. "It has been a very active virus to date," he said, and "further spread will undoubtedly lead to more infections, both in birds and humans. " He said researchers are now awaiting publication of the genetic sequence, which will provide more information about whether there have been further changes that could make it more severe and/or transmissible. According to the WHO, the young girl's symptoms, which included fever, malaise and vomiting, began on March 7. She was admitted to a hospital in the state of Durango on March 13 due to respiratory failure. She was treated with oseltamivir, an antiviral drug, the following day. On March 16, she transferred to another hospital in the city of Torreón. She died on April 8 from "respiratory complications." The girl did not have any underlying medical conditions, had not received a seasonal influenza vaccination, and had no history of travel, according to the WHO report. The source of the child's infection remains under investigation. According to the report, 91 people were identified as contacts of the toddler, including 21 household contacts, 60 healthcare workers and 10 people from a childcare center. Each of these people was tested and all have tested negative for the virus. Between 2022 and August 2024, there have been 75 reported H5N1 poultry outbreaks across Mexico, although none in Durango. At the end of January 2025, a sick vulture at the Sahuatoba Zoo, in Durango, was diagnosed with the virus. In addition, dozens of wild birds in the state were also reported, including a Canada goose. The virus is still circulating in U.S. dairy herds, poultry, wild birds and wild mammals. Since April 1, there have been five new reports of infected dairy herds from California, 15 in Idaho and one from Arizona, according to the US Department of Agriculture. There have also been dozens of domestic cats infected with the virus, including three recent reports from California's Orange and Alameda counties: two in Orange and one in Alameda. According to the U.S. Centers for Disease Control and Prevention, there have been 70 reported cases of H5N1 bird flu in the U.S. since March 2024, when the virus was first reported in dairy herds. There has been one death, a person older than 65 from Louisiana. Health officials say the risk of H5N1 bird flu to the general public remains low and there has been no indication of person-to-person spread. Most cases have been associated with contact with infected livestock and poultry. This story originally appeared in Los Angeles Times.
Los Angeles Times
18-04-2025
- Health
- Los Angeles Times
Mexican child infected with H5N1 bird flu dies from respiratory complications
A 3-year-old girl in Mexico died this month after getting infected with H5N1 bird flu, according to a report issued by the World Health Organization this week. Authorities say the strain of bird flu is one that has been circulating in wild birds throughout North America, known as D1.1. It is the same strain implicated in the death of a person in Louisiana earlier this year, and in the case of a 13-year-old Canadian who was placed on life-support for several weeks before recovering. Two others, a person in Wyoming and a poultry worker in Ohio, were also reported to have severe disease after exposure to this strain of the virus. The strain has been detected in dairy herds from Nevada and Arizona. 'The case in Mexico is another great reminder of how dangerous H5 viruses can be,' said Richard Webby, an infectious disease expert at St. Jude Children's Research Hospital in Memphis, Tenn. The D1.1 strain is widespread in the U.S. and Canada, but until this week's WHO report it was unclear how far south the strain had traveled, he said. 'It has been a very active virus to date,' he said, and 'further spread will undoubtedly lead to more infections, both in birds and humans. ' He said researchers are now awaiting publication of the genetic sequence, which will provide more information about whether there have been further changes that could make it more severe and/or transmissible. According to the WHO, the young girl's symptoms, which included fever, malaise and vomiting, began on March 7. She was admitted to a hospital in the state of Durango on March 13 due to respiratory failure. She was treated with oseltamivir, an antiviral drug, the following day. On March 16, she transferred to another hospital in the city of Torreón. She died on April 8 from 'respiratory complications.' The girl did not have any underlying medical conditions, had not received a seasonal influenza vaccination, and had no history of travel, according to the WHO report. The source of the child's infection remains under investigation. According to the report, 91 people were identified as contacts of the toddler, including 21 household contacts, 60 healthcare workers and 10 people from a childcare center. Each of these people was tested and all have tested negative for the virus. Between 2022 and August 2024, there have been 75 reported H5N1 poultry outbreaks across Mexico, although none in Durango. At the end of January 2025, a sick vulture at the Sahuatoba Zoo, in Durango, was diagnosed with the virus. In addition, dozens of wild birds in the state were also reported, including a Canada goose. The virus is still circulating in U.S. dairy herds, poultry, wild birds and wild mammals. Since April 1, there have been five new reports of infected dairy herds from California, 15 in Idaho and one from Arizona, according to the US Department of Agriculture. There have also been dozens of domestic cats infected with the virus, including three recent reports from California's Orange and Alameda counties: two in Orange and one in Alameda. According to the U.S. Centers for Disease Control and Prevention, there have been 70 reported cases of H5N1 bird flu in the U.S. since March 2024, when the virus was first reported in dairy herds. There has been one death, a person older than 65 from Louisiana. Health officials say the risk of H5N1 bird flu to the general public remains low and there has been no indication of person-to-person spread. Most cases have been associated with contact with infected livestock and poultry.
Yahoo
19-03-2025
- Health
- Yahoo
New strain of bird flu wipes out Mississpi poultry farm; human flu may offer immunity
A new strain of a highly pathogenic bird flu known as H7N9 has surfaced at a poultry farm in Mississippi where chickens are raised for breeding. The finding of the new strain came as researchers separately reported a potentially positive development: Exposure to human seasonal flu may confer some immunity to H5N1 bird flu. The new strain found in Noxubee County, Miss., was confirmed March 12 and all of the roughly 46,000 birds either died or were euthanized after the infection spread, according to the U.S. Department of Agriculture's Animal Plant Health Inspection Service and Mississippi's Board of Animal Health. None of the birds entered the food supply. Authorities didn't say how the birds were infected, although federal wildlife agents had been identifying low-pathogenic versions of the H7N9 virus for several years in wild birds. It is possible that the version found in the chickens is circulating in wild birds, but most researchers think it probably acquired it's deadly attributes once it got into the Noxubee chicken operation. And if that's the case, "my money is on a one-and-done, perhaps with some local spread," said Richard Webby, an infectious disease expert at St. Jude Children's Research Hospital in Memphis, Tenn. Webby said most bird flu outbreaks follow that pattern: A low-pathogenic version is introduced to commercial poultry, and it becomes highly pathogenic once inside. The introduction of H5N1 — the bird flu virus that's been infecting dairy cows, commercial poultry, pet cats, wild animals and wild birds since March 2024 — into poultry and livestock populations was a notable exception to this trend: It was already circulating among wild birds and animals as a highly pathogenic virus. John Korslund, a veterinarian and former USDA researcher, agreed with Webby and noted that the operation housed breeder broilers: Chickens that are grown and maintained for breeding purposes, not for their meat. This is significant because breeders live for months, if not years. If a low-pathogenic virus "happens to get into a broiler meat flock, the birds don't get sick and they go onto slaughter," he said. But when a breeder flock picks up that virus, "the virus can replicate for weeks ... this may well be what happened in Mississippi." However, according to USDA rules, routine and periodic testing of breeder birds for low-pathogenic avian influenzas is required. In 2017, an outbreak of H7N9 occurred along the Mississippi flyway, probably starting in late February, but reported only in March. A summary report of the outbreak suggested the virus was introduced via wild birds. As suspected in this case, it is believed it started as "low path" and only became "high path" once it got into the commercial operation. Nevertheless, experts said, if they are wrong and a highly pathogenic virus is circulating in wild birds, it'll start popping up in other states and sites too. "Time will tell how nasty it gets this time," Korslund said. The key to preventing these kinds of outbreaks — or at least getting ahead of them — is wildlife surveillance, the experts said. Agencies such as the USDA, the U.S. Fish and Wildlife Service, the U.S. Geological Survey's Wildlife Health Center, and the National Oceanic and Atmospheric Administration have divisions that are tasked with sampling wild birds and other animals for infectious diseases. The information they gather is then used by agriculture and public health officials to determine where and when to bolster biosecurity, or to keep a lookout. Without that information, said Angela Rasmussen, a virologist at the University of Saskatchewan's Vaccine and Infectious Disease Organization in Canada."we're flying blind." In the positive news that came out this week, a team of international researchers found that ferrets exposed to a common seasonal human flu — H1N1 — before being exposed to H5N1, acquire some immunity from the seasonal flu. Ferrets that weren't exposed to the seasonal flu before being infected with H5N1 had high levels of the virus in their respiratory tissues, as well as detectable virus in their hearts, spleen, liver and intestines. In contrast, those that had been exposed to the seasonal flu beforehand had virus only in the respiratory tract — and at pretty low levels. "The biggest take home message of our data is that prior human seasonal virus infection can provide some level of protection against the lethality of bird flu," said Seema Lakdawala, a microbiologist at Emory University in Atlanta and one of the study's researchers. Webby, the St. Jude researcher, said the work supports other research that has looked at the potential protectiveness of prior exposure to flu viruses. "It is for sure playing some role in modulating H5N1 disease in humans," he said, but was unlikely the only factor. "After all, many people have severe seasonal H1N1 infections each year despite lots of immunity to the virus from previous H1N1 exposures." But the finding may help explain why the virus recently has been associated with generally mild disease in the people who have been infected. Seventy people in the U.S. have been infected since March 2024, and one person has died. (Four people, including the Louisiana patient who died, have been hospitalized). Before last year, the virus was thought to have killed roughly 50% of those infected. Rasmussen said the worry now is that if H5N1 mutates to become transmissible between people, it'll be young children as well as the old and compromised who are likely to be most affected. Children younger than 5 are less likely to have been exposed to seasonal human influenza viruses than school-aged children and adults — potentially making them more susceptible to the harms of a virus such as H5N1. In addition, she said, the bird flu viruses circulating in birds and livestock "as far as we know, can't transmit easily between people. But, if there's reassortment, then who knows? We don't know what kind of residual population-level immunity we would have" from a virus such as that. How seasonal flu vaccines could affect this protection isn't clear. "Seasonal vaccines will not provide the same diversity of immune response as natural infection and unlikely to provide the same level of protection," said Lakdawala, who is testing this issue in the lab. This story originally appeared in Los Angeles Times.
