Virus World

The CDC said Thursday that the mutations, detected in a sample taken from a Louisiana patient, may help bind the virus to the upper airways in people. Genetic sequences of H5N1 bird flu viruses collected from a person in Louisiana who became severely ill show signs of development of several mutations thought to affect the virus’ ability to attach to cells in the upper airways of humans, the Centers for Disease Control and Prevention reported on Thursday. One of the mutations was also seen in a virus sample taken from a teenager in British Columbia who was in critical condition in a Vancouver hospital for weeks after contracting H5N1. The mutation seen in both viruses is believed to help H5N1 adapt to be able to bind to cell receptors found in the upper respiratory tracts of people. Bird flu viruses normally attach to a type of cell receptor that is rare in human upper airways, which is believed to be one of the reasons why H5N1 doesn’t easily infect people and does not spread from person-to-person when it does. Scott Hensley, a professor of microbiology at the University of Pennsylvania’s Perelman School of Medicine, cautioned against reading too much into data from two severe cases, though he admitted the CDC’s report was “enough to raise my eyebrows.” “It’s not great. It’s not great news,” Hensley told STAT.

The CDC reported its scientists had compared viruses collected from the unidentified Louisiana patient to one from infected poultry on the person’s property. The mutations seen in the patient’s samples were not present in the virus from the birds, which suggests the mutations were developing during the course of the person’s infection.  “The changes observed were likely generated by replication of this virus in the patient with advanced disease rather than primarily transmitted at the time of infection,” the report stated. That is believed to have been the case with the British Columbia patient as well, though health officials there had no source virus to study because they could never determine how the teen became infected.  Hensley said it would have been more concerning if the mutations had been seen in the virus from the birds, because it would have suggested viruses in nature were acquiring these changes. Angela Rasmussen, a virologist who specializes in emerging infectious diseases, agreed that the news would have been worse if the mutations had been seen in the virus from the Louisiana patient’s poultry. But she called the current H5N1 situation “grim,” noting there has been an explosion of human cases. “More [genetic] sequences from humans is a trend we need to reverse — we need fewer humans infected, period,” said Rasmussen, who works at the University of Saskatchewan’s Vaccine and Infectious Disease Organization in Saskatoon, Canada, said on the social media site X (formerly known as Twitter). “We don’t know what combination of mutations would lead to a pandemic H5N1 virus and there’s only so much we can predict from these sequence data. But the more humans are infected, the more chances a pandemic virus will emerge.” There have been at least 65 confirmed human cases of H5N1 bird flu this year in the United States, since the ongoing outbreak of H5N1 in dairy cows was first confirmed in late March. About 60% of the cases have been people who were infected after having contact with infected cows; most of the others have been infected by contact with infected poultry, either while culling birds at affected commercial operations or, in the case of the person from Louisiana, through contact with an infected backyard flock. In two cases the source of infection was not found.

The version of the virus that is circulating in cows is slightly different from the one found in wild birds and in most of the poultry farm outbreaks. The cattle virus is clade 2.3.4.4b genotype B3.13 while the version in birds is 2.3.4.4b genotype D1.1 or D1.2.  Both the Louisiana and the British Columbia cases were caused by genotype D1.1 viruses. They are the only two severe infections reported in North America in 2024. The current condition of the Louisiana case is not known. “We are not providing updates about the patient’s condition at this time,” Emma Herrock, communications director of Louisiana’s Department of Health, said Thursday via email. Hensley said his laboratory is working to test if the mutations seen in the virus from the British Columbia teen do actually increase binding to human cells, as is believed. He expects to have results of that work in early January. Even if they do, it isn’t clear that would be enough to allow the virus to easily infect people, and to transmit from person to person, he said. It is thought that other changes in other parts of the virus would be needed. “We know attachment is a prerequisite but it might not be enough,” he said. There was no onward transmission seen from the British Columbia teenager. And Louisiana has found no secondary cases among contacts of the person who was hospitalized.  The CDC said it is working with the Louisiana Department of Public Health to generate genetic sequences of samples taken later in the person’s infection, to see if additional mutations developed. 

 — Megan Molteni contributed reporting.

Correction: An earlier version of this article misstated the genotype of the H5N1 virus circulating in cows.

CDC report (Dec. 26, 2024):

https://www.cdc.gov/bird-flu/spotlights/h5n1-response-12232024.html 

A new study finds tweaking part of the H5N1 virus infecting dairy cows in a single spot could allow it to better attach to human cell receptors, raising concerns it could transmit more easily between people. Scientists have discovered that H5N1, the strain of highly pathogenic avian influenza virus currently spreading in U.S. dairy cows, only needs a single mutation to readily latch on to human cells found in the upper airway. The findings, published today in Science, illustrate a potential one-step path for the virus to become more effective at human transmission—and could have major implications for a new pandemic if such a mutation were to become widespread in nature. Avian influenza viruses are dotted with surface proteins that allow them to bind to bird cell receptors, which permit the virus to enter the cells. The cell receptors in birds are different from those in humans, but that variation is “very subtle,” says James Paulson, a study co-author and a biochemist at Scripps Research. “For a new pandemic H5N1 virus, we know that it has to switch receptor specificity from avian-type to human-type. So what will it take?” To his and his co-authors’ surprise, that switch only needed one genetic alteration. The particular group, or clade, of H5N1 responsible for the current outbreak was first detected in North America in 2021 and has affected a wide range of animal populations, including wild birds, bears, foxes, a variety of marine mammals and, most recently, dairy cows. Since outbreaks of H5N1 in U.S. dairy herds began this spring, human cases have been mostly linked to sick poultry or cows, and the majority of human infections have been mild ones among farmworkers at high risk of exposure (with some notable exceptions). There haven’t been any signs of transmission between people—and the virus’s receptor binding preference is a key barrier to that.

“It’s obviously speculative, but the better the virus becomes at likely binding to human receptors—it’s not great because it’s going to probably lead to human-to-human transmission,” says Jenna Guthmiller, an immunologist at the University of Colorado Anschutz Medical Campus, who was not involved in the new research. The study authors focused on altering one of H5N1’s surface proteins, hemagglutinin, which contains the binding site that allows the virus to latch onto host cell receptors and kick-start infection. The researchers generated viral proteins from genetic sequences of the virus isolated from the first human case in Texas, which occurred in a person who developed bird flu after exposure to an infected cow. No live virus was used in the experiment. Then the scientists engineered an assortment of different mutations into hemagglutinin’s chain of amino acids, or protein building blocks. A single mutation that swapped the 226th amino acid in the sequence for another allowed H5N1 to switch its binding affinity from receptors on bird cells to receptors on human cells in the upper respiratory tract. Past research has shown that several influenza mutations, including the ones tested in the new paper, are important in human receptor binding, Guthmiller says. These genetic tweaks have been flagged in previous influenza virus subtypes that have caused human pandemics, such as those in 1918 and 2009. But past viruses typically required at least two mutations to successfully change their preference to human receptors, explains co-author Ian Wilson, a structural and computational biologist at Scripps. “This was surprising. It was just this single mutation [that] was sufficient to switch the receptor specificity,” he says. Paulson adds that the particular mutation the scientists tested in the new study had previously been investigated during H5N1 outbreaks in poultry and some humans in 2010, but it didn’t affect the virus’s human receptor binding. “But the virus has subtly changed,” Paulson says. “Now that mutation does cause the change.”

Wilson and Paulson note the mutated H5N1 protein in their study bound weakly to human receptors but more strongly than the 2009 H1N1 virus, which caused the “swine flu” human pandemic. “The initial infection is what we’re concerned about to initiate a pandemic, and we believe that the weak binding that we see with this single mutation is at least equivalent to a known human pandemic virus,” Paulson says. The study did identify a second mutation in another area of hemagglutinin, the amino acid at position 224, that could further enhance the virus’s binding ability in combination with the 226 mutation. Guthmiller isn’t surprised about the findings, given the 226 mutation’s known significance in flu receptor preference, but adds, “It’s never great when you see that it only really takes one mutation.” The study “also sort of provides us an idea of what we should be looking for and what sites of the hemagglutinin protein we should be focusing on to understand its potential to change and infect us better.” A teenager in Canada was recently hospitalized in critical condition from bird flu with an unknown exposure. Genetic sequencing, which showed a strain of H5N1 that was similar to one circulating in Canadian poultry, detected mutations in two positions, one of which was at 226—the same position studied in the new paper. Scientists don’t know if either mutation was responsible for the teenager’s severe condition, but some expressed concern that the changes could be a sign of the virus potentially adapting to human cells.

Paulson says it’s too early to draw conclusions or parallels between the teenager’s case and the study findings. The amino acids the researchers tweaked in the study were not the same as those in the Canadian case’s viral sequence, for instance, he says. “There’s a lot of chatter that, ‘oh, my gosh, that amino acid is mutating,’ but there’s no evidence yet that that would actually give us the specificity that would be required for human transmission,” Paulson says. But he adds that the case is still significant. Most bird flu cases in humans reported this year have been mild. In past outbreaks, H5N1 has caused severe respiratory disease because of its preference to bind to cells in the lower respiratory tract, Guthmiller explains. "You’re basically causing a viral pneumonia,” she says. “But if you increase binding to human receptors that are in the upper respiratory tract,” as this study did, “that’s more likely going to look more like your common cold–like symptoms.” That said, viruses that prefer the upper respiratory tract, including the nose and throat, are more likely to spread through coughing and sneezing, she says. That could lead to more spread through human contact. Better receptor binding doesn’t necessarily cause disease on its own. Several other factors are important, such as the virus’s ability to replicate and proliferate in the body. But attaching to cells is an initial step, Paulson says. “The magic that we hope doesn’t happen is that all of those things come together so that we have that first [human-to-human] transmission and that becomes a pandemic virus,” he says.

The jabs are being stockpiled in case H5N1 adapts to spread between humans. Britain has secured five million doses of H5 bird flu vaccine to prepare for a possible global pandemic, the UK Health Security Agency (UKHSA) announced today. The jabs, made in Liverpool, are being stockpiled in case H5N1 bird flu adapts to spread between humans – which could trigger a pandemic – the agency said. H5N1 has spread rapidly in farms across the US and Europe in recent months, with more than 50 human cases recorded in the US alone. The vaccine has been developed by the Australian-owned company CSL Seqirus (CSLS) at its main UK manufacturing plant in Speke, Liverpool. They have already been used to protect workers in Finland, where H5N1 spread amongst farmed mink last year. The Finnish government procured 10,000 doses – although only 450 people took up the offer to get jabbed. This year, the virus – which originated in birds but has shown the ability to ‘jump’ to other mammals – has rapidly spread amongst US dairy cattle this year. The people infected in the US have mainly been farm workers who suffered only very mild diseases. However, a teenager who recently acquired the infection in Canada through an unknown source has been in critical condition for over a month and remains in intensive care.

H5N1 has also been found in poultry flocks in Cornwall and Yorkshire in recent months, although no human cases have yet been detected in the UK. Experts have repeatedly called for governments to strengthen their H5 preparedness operations ahead of the winter flu season due to fears of reassortment – the mixing of genetic material between seasonal flu and animal flu-like H5N1. The process is more likely in winter, as flu cases surge. This raises the risk of animals and humans contracting both viruses and creating a new, more transmissible strain. The 2009 swine flu pandemic resulted from the same process. “It is important for us to be prepared against a range of different influenza viruses that may pose human health risks. Early access to vaccines saves lives. Adding H5 vaccines to the interventions already available to us will help us to be ready for a wider range of threats,” Dr Meera Chand, Emerging Infection Lead at the UKHSA said. The procurement will strengthen the UK’s preparedness for an H5N1 pandemic by ensuring that vaccines are immediately available, while a pandemic-specific vaccine is made ready, UKSHA said.

The circumstances and positive testing of a raw milk sample in California don't make sense, say experts. Something is amiss.  Less than a week after California health officers confirmed a finding of bird flu virus in store-bought raw milk, state agriculture officials descended on Mark McAfee’s Raw Farm dairy “like never before” Wednesday and began collecting samples from the farm’s two herds, creamery, bulk milk tanks and trucks, according to the owner. The visit follows a recall of Raw Farm products, and also comes amid a growing series of H5N1 bird flu outbreaks in state dairy farms. Raw Farm maintains 1,800 head of cattle spread over two herds — one in Fresno, the other outside of Hanford, according to McAfee. The company also owns a Fowler-based creamery. “I think they are on full attack mode,” he said, describing the search as thorough. In addition to milk, Raw Farm produces cheese and kefir. As California Department of Food and Agriculture officials collected samples and conducted tests at the dairy Wednesday, some health experts raised questions and concerns about the recent positive test results.

Last week, public health officials in Santa Clara County detected bird flu virus in a store-bought sample of McAfee’s raw milk. Two days later, the California Department of Public Health confirmed the finding. But when state agriculture officials tested cows at McAfee’s dairy farm on Monday, they failed to detect the virus. The fact that none of the animals are known to be infected with the virus has puzzled and concerned public health experts. Generally, once the virus appears on a farm, it spreads and does not just disappear. “The fact that all the supplemental testing is negative really bothers me,” said John Korslund, a retired U.S. Department of Agriculture veterinarian epidemiologist, in an email. Officials from the CDFA could not be reached for comment Wednesday, but infectious disease experts told The Times that officials probably were reviewing testing procedures, as well as the actual origin of the sampled milk. According to testing records, the initial sample of store-bought raw milk carried high levels of the virus, and was found to have a polymerase chain reaction cycle threshold — or Ct — of roughly 25. “A herd should not be immediately negative after a reading of 25 if it is truly milk from the same herd, IMO,” Korslund wrote in an email.

Richard Webby, director of the World Health Organization’s Collaborating Center for Studies on the Ecology of Influenza in Animals and Birds, and a researcher in the department of infectious diseases at St. Jude Children’s Research Hospital in Memphis, Tenn., agreed. “OK, that’s not a weak positive … and definitely not on the borderline where some tests would be positive and others negative,” he said after reviewing the test records. Webby, Korslund and other experts say the test that was used only looks for the H5 part of the H5N1 virus, and it can’t determine if the virus is inactive or alive. A second test — one called a virus isolation test — needs to be done to confirm the sample is H5N1 and that it is active. State and federal health officials say the H5N1 bird flu virus poses a low risk to the public. However, they have urged people not to drink raw, unpasteurized milk. There has been no reported outbreak in consumers associated with the bird flu in contaminated raw milk. The milk was bottled on Nov. 9. Raw Farm has recalled all products associated with the positive sample. McAfee estimates the recall involved roughly 2,000 gallons of half- and quarter-gallon “cream top” whole milk products.

Since the beginning of the outbreak, 461 herds have been infected in California — including herds in Fresno and Kings County, where McAfee’s herds are located. Early in the H5N1 dairy outbreak, federal health officials tested pasteurized milk samples and found virus in 20% of the samples collected from retail shelves. However, when further testing was conducted — virus isolation — they were able to show it was inactivated virus that had been denatured by heat. So, why then would a raw milk sample test high for virus and a dairy herd not test positive? Korslund acknowledged that testing and sampling can sometimes be compromised, but he was not inclined to doubt the tests in this instance. He said the Ct value — and the lack of subsequent positive tests — suggests a “product integrity issue rather than a herd infection.” “What if somewhere in the bottling process, pasteurized shelf milk was spiked into the raw milk to meet inadequate supply demands? In such a scenario, we don’t have a testing issue; rather it’s a product integrity issue that normally would be undetectable,” he said. This is why virus isolation testing is critical, Korslund said. It would help determine whether the virus in the sample collected was alive or not.

A spokesman for the state’s health department said testing on the sample was complete. He did not say whether viral isolation had been completed, but noted the positive result has been confirmed by state and now federal laboratories. McAfee said he does not think the virus is present in his herd. The tests that the state’s agriculture department have been regularly conducting — twice a week — on his bulk milk have been negative. In addition, he noted, a test taken on Monday also showed no virus. He said he also monitors each cow at his farms with a high-tech device — made by the Austrian company smaXtec — that sits in a cow’s udder and sends real-time information about the animal’s body temperature, milk acidity, etc. He said there are no indications that virus is moving through his herd based on those data. He also said all his operations — including his trucks, his bulk tanks and bottling plant — are closed to outside farms and milk; they are used only by Raw Farm. He said he’s worried state officials are determined “to find something.”

The infection brings the reported number of U.S. bird flu cases this year to 55, including 29 in California, the CDC said. Most were farmworkers who tested positive with mild symptoms. Health officials on Friday confirmed bird flu in a California child — the first reported case in a U.S. minor. The child had mild symptoms, was treated with antiviral medication and is recovering, the Centers for Disease Control and Prevention said in announcing the test results. State officials have said the child attends day care and lives in Alameda County, which includes Oakland and surrounding communities, but released no other details. The infection brings the reported number of U.S. bird flu cases this year to 55, including 29 in California, the CDC said. Most were farmworkers who tested positive with mild symptoms. One exception was an adult in Missouri who did not work at a farm and had no known contact with an infected animal. It remains a mystery how that person was infected — health officials have said there was no evidence of it spreading between people.

A British Columbia teen also was recently hospitalized with bird flu, Canadian officials have said. H5N1 bird flu has been spreading widely in the U.S. among wild birds, poultry and a number of other animals over the last few years. It began spreading in U.S. dairy cattle in March. California has become the center of that outbreak, with 402 infected herds detected there since August. That’s 65 percent of the 616 herds confirmed with the virus in 15 states. Officials said they were investigating how the child was infected. California health officials previously said in a statement that they were looking into a “possible exposure to wild birds.” There is no evidence bird flu spread from the child to other people. People in the child’s household reported having similar symptoms, but their test results were negative for bird flu. Health officials noted the child and the household members also tested positive for other common respiratory viruses.

CDC Press Release (2024):

https://www.cdc.gov/media/releases/2024/p1122-h5n1-bird-flu.html 

The H5N1 bird flu strain circulating in U.S. dairy cattle is likely infecting far more farm workers than scientists realized, a new study published today by the U.S. Centers for Disease Control and Prevention (CDC) suggests. Tests of 115 dairy workers exposed to the virus in two states found evidence of a recent H5N1 infection in eight of them—an infection rate of 7%—researchers report today in the agency’s Morbidity and Mortality Weekly Report. The United States has reported 46 H5N1 infections in humans so far, 45 of them linked to infected poultry and cattle. But thousands of dairy workers have likely been exposed to infected herds, and the new study suggests many cases have been missed, says Caitlin Rivers, an epidemiologist at the Johns Hopkins Center for Health Security. “There are dairy infections in dozens of states, and so likely most, or all of those states will have experienced human cases.” In response to the findings, CDC plans to increase testing of exposed farm workers, and it recommends more people take an antiviral drug to reduce their risk. But the agency stresses there is no evidence the virus has become better at spreading between humans, and it still classifies the risk to the general public as low. To researchers worried about an influenza pandemic, H5N1 is a top concern. A strain named clade 2.3.4.4b has recently spread around the globe, affecting wild birds or poultry on every continent except Australia. The virus likely jumped to U.S. dairy herds last fall but wasn’t detected there until March. Testing for human cases has been scant.

Between June and August, CDC researchers collected blood from the 115 workers on dairy farms in Michigan and Colorado that had reported cattle infections, and tested their blood for antibodies against clade 2.3.4.4b. (Additional tests were done to rule out seasonal influenza infections.) Of the eight people who showed signs of a past H5N1 infection, four remembered feeling ill with mild symptoms, including three who reported red, itchy eyes—the conjunctivitis seen in many of the previously known infections in the U.S. CDC now recommends all farm workers exposed to H5N1-infected animals get tested, not just those who have symptoms. That should help identify, treat, and isolate more cases, CDC Principal Deputy Director Nirav Shah said at a press conference today: “Simply put, the less room we give this virus to run, the fewer chances it has to cause harm or to change.” The agency is also recommending that workers on affected farms who have had a high-risk exposure, such as a splash of milk in the face with raw cow milk, receive prophylactic treatment with oseltamivir, an antiviral medication also known as Tamiflu. “It reduces the likelihood of an asymptomatic case [becoming] symptomatic,” Shah said, “and the chances of onward transmission to close contacts.” All of the workers who showed signs of H5N1 infection reported milking cows or cleaning the milking parlor, a sign these activities carry a higher risk, said Demetre Daskalakis, who heads CDC’s National Center for Immunization and Respiratory Diseases. In an update to its guidance, CDC recommends people who carry out these duties wear protective equipment, including safety goggles and a respirator.

The sheer number of human infections is worrying, says viral immunologist Scott Hensley of the University of Pennsylvania Perelman School of Medicine. “Every time the virus infects a human, there is a chance of random mutations that could increase the ability of this virus to infect humans.” The big unknown is whether the virus will change to cause more serious illness in humans, says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. He is far less worried about conjunctivitis than about typical flu symptoms such as fever, coughing, and sneezing. “The question is: Is this a stepping stone to getting to classic influenza? Because that is the real risk to the public’s health,” Osterholm says. “And at the moment we just don’t know.” Rivers agrees that the fact that the cases all appear to be mild or asymptomatic is reassuring, but that could be because the workers were young, she says. Virologist Marion Koopmans of Erasmus Medical Center says more serious cases could yet occur. The situation reminds her of a massive outbreak of H7N7, another bird flu strain, in poultry in the Netherlands in 2003. It caused 88 confirmed human cases with conjunctivitis, but mutations in the virus that infected one veterinarian led to severe disease, and eventually, death. Blood tests by Koopmans and colleagues done after the outbreak ended showed that all in all, more than 1000 people became infected, many of them without any symptoms. Even if the risk of a pandemic appears low for now, the results are another warning that the U.S. needs to do more to bring H5N1 in cattle under control, says Albert Osterhaus, a virologist at the University of Veterinary Medicine Hannover: “Even a low risk of a looming catastrophe should be tackled at the source.”

Publisjed in Science (Nov. 07, 2022):

https://doi.org/10.1126/science.z3b9l2x

No concern about the safety of the nation’s pork supply.

USDA's Animal and Plant Health Inspection Service is sharing key updates regarding the detection of HPAI H5N1 in a backyard farm operation in Crook County, Oregon, as well as additional information about the agency’s proactive efforts to protect livestock, farms and communities from avian influenza.   On Wed., Oct. 30, USDA APHIS announced that H5N1 avian influenza was detected in one of the pigs at this backyard farm, that two pigs tested negative, and tests were pending for two additional pigs.  The USDA National Veterinary Services Laboratories has completed testing on the two remaining pigs and has confirmed that one tested positive and met the clinical case definition for HPAI H5N1. Sequencing from this positive sample, while incomplete due to the low level of the virus, indicates infection from the D1.2 genotype of H5N1.    Because the amount of virus from the infected pigs was very low, only partial genomic sequences could be extracted from one of the two samples and these sequences indicate infection with the D1.2 genotype of H5N1. APHIS and the Oregon Department of Agriculture had previously also shared that H5N1 had been detected in poultry on the same farm; the samples from the poultry were also found to have the D1.2 genotype.   

Genomic sequencing of samples from migratory birds in the area showed very similar sequences, which increases the probability that the pigs and poultry on this farm became infected after coming into contact with infected migratory birds, not dairy cattle or other livestock.     This farm is a non-commercial operation, and the animals were not intended for the commercial food supply. There is no concern about the safety of the nation’s pork supply as a result of this finding.      Additionally, over the past week APHIS has approved field safety trials for two additional vaccine candidates for H5N1 in cattle, bringing the total number of candidates approved for field trials to four. USDA continues to support the rapid development and timely approval of an H5N1 vaccine for dairy cows, in addition to other species.   Last week, as part of USDA’s broader efforts to combat the spread of H5N1, APHIS announced plans to partner with State and animal health officials to enhance testing and monitoring for H5N1, building on measures taken by USDA since the beginning of the avian influenza outbreak. This strategy builds on measure taken by states, as well as national risk mitigation measures including the Federal Order requiring testing of lactating cattle prior to interstate movement, which was announced in April 2024. The state of Colorado’s bulk milk testing program has been highly successful, with no herds currently containing cattle infected with H5N1 and has helped inform the design of this new milk testing strategy.  

In partnership with state veterinarians, USDA will implement a tiered strategy to collect milk samples to better assess where H5N1 is present, with the goal to better inform biosecurity and containment measures, as well as to inform state-led efforts to reduce risk to farm workers who may be in contact with animals infected with H5N1. USDA intends to begin implementation of this strategy within 30 days of the announcement. USDA will continue to work with state and private veterinarians on the final details of implementation, and will share guidance documents soon.     USDA continues to emphasize to farmers nationwide that biosecurity is the best weapon against the spread of H5N1, and farms should practice good biosecurity even if the virus has not been detected in their state or vicinity. Data collected over the past seven months has shown that H5N1 can be transmitted on equipment, people or other items that move from farm to farm, including between dairies and poultry facilities. USDA’s Federal Order to require testing before cattle movement between states has helped limit the spread of H5N1, but local and state efforts to enhance biosecurity measures remain just as important. USDA strongly encourages herd owners to participate in available producer support programs, which help to cover the cost such as biosecurity programming, PPE for employees and veterinary care.  Producers can find more information on the APHIS website or at their nearest USDA Farm Service Agency county office.  As USDA takes additional steps to protect the health of livestock, the department will continue to work closely with its federal partners at CDC to protect the health of people and FDA to protect the safety of the food supply. These collective, collaborative efforts have helped protect farmworkers and farmers, the health and welfare of livestock animals, and reaffirmed the safety of the nation’s food supply. The U.S. government remains committed to addressing this situation with urgency.  Learn more about USDA’s response to HPAI in dairy cattle on the APHIS website.

USDA Press Release:

https://www.aphis.usda.gov/news/agency-announcements/usda-animal-plant-health-inspection-service-shares-update-h5n1-detection 

Emails show concerns about potential human-to-pet transmission, with cases in cats now confirmed in multiple states. Internal emails reveal Michigan health officials suspected that owners may have inadvertently spread bird flu to their household cats, raising new concerns about transmission patterns of the virus. "If we only could have gotten testing on the [REDACTED] household members, their clothing if possible, and their workplaces, we may have been able to prove human-to-cat transmission," officials wrote in a July 22 email obtained by KFF Health News. Another email urged publishing a report "to inform others about the potential for indirect transmission to companion animals." The emails were obtained via record requests and document the ongoing struggle to track cases of the H5N1 virus in cats. They suggest that domestic cats may become infected from droplets known as fomites on their owners' persons. These communications mark the latest in a slew of recent cat-related infections across the U.S., most notably in Colorado, where six cats have tested positive for H5N1 in 2024. Two of these cases occurred in indoor-only cats with no direct exposure to infected animals. The Colorado infections were confirmed by the Colorado Veterinary Medical Association (CVMA) in an update posted on its website in August. "One of these cases was directly associated with a known infected commercial dairy facility," the update said. "Two of the six cases were indoor only cats with no direct exposures to the virus. Three of the six cases were known indoor/outdoor cats that hunted mice and/or small birds as prey and also spent time indoors with their owners." The spread of bird flu to household pets marks a significant development in an outbreak that has primarily affected poultry and cattle.

A map posted on the U.S. Department of Agriculture (USDA) website, last updated on October 29, reveals domestic cats have been infected far and wide, including in Texas, Oregon, Ohio, Minnesota, Montana and Idaho. "There have been 53 detections in domestic cats since the onset of the 2022 outbreak," Will Clement, senior advisor for strategic communications at the USDA, told Newsweek. Clement explained that other than the two indoor-only cats, the rest were outdoor cats close to infected premises or stray cats on farms. Kristen Coleman, an assistant professor at the University of Maryland School of Public Health, has documented a "drastic rise" in feline infections beginning in 2023, coinciding with the rapid spread of the current H5N1 strain among mammals. "As companion animals, domestic cats provide a potential pathway for avian influenza viruses to spillover into humans," Coleman said in a June statement coinciding with a study she authored on the spread of bird flu in cats. "We looked at the global distribution and spread of bird flu infections in feline species between 2004 and 2024 and found a drastic rise in reports of feline infections starting in 2023, with a spike in infections reported among domestic cats, as opposed to wild or zoo-kept animals. This increase coincides with the rapid spread of the current strain of H5N1 among mammals." Coleman advised owners not to feed their cats raw meat or dairy and to limit unsupervised time outdoors in order to prevent infection. Cats may exhibit respiratory symptoms, such as difficulty breathing, and in some cases can go blind as a consequence of bird flu.

On its website, the Centers for Disease Control and Prevention acknowledged cats' susceptibility to bird flu, while maintaining that the risk to the general public remains low. The agency's website noted that domestic animals can become infected if they "eat or be exposed to sick or dead birds infected with bird flu viruses, or an environment contaminated with bird flu virus." As health officials continue monitoring the situation, the Michigan emails highlight the challenges in tracking and preventing transmission through indirect routes. "The virus is going to sneak up in more places, just like it did in dairy farms," Coleman said. "We know cats are being infected, so let's get ahead of it."

The findings highlight the risks posed by a virus that continues to spread among dairy cattle and occasionally to farm workers, and the study's lead scientist says he was surprised by the ease with which this particular strain was able to kill ferrets.  A strain of H5N1 avian influenza virus found in a Texas dairy worker who was infected this spring was able to spread among ferrets through the air, although inefficiently, and killed 100% of infected animals in studies University of Wisconsin–Madison researchers performed with the strain earlier this year. The good news: the dairy worker experienced mild symptoms and fully recovered, and the H5N1 strain that infected the worker does not appear to have continued spreading in the wild. Still, the findings highlight the risks posed by a virus that continues to spread among dairy cattle and occasionally to farm workers, and the study’s lead scientist says he was surprised by the ease with which this particular strain was able to kill ferrets. “This is one of the most pathogenic viruses I’ve ever seen in ferrets,” says Yoshihiro Kawaoka, a UW–Madison professor of pathobiological sciences who spearheaded the work, described Oct. 28, 2024, in the journal Nature.

Ferrets are a common model for studying how influenza viruses that primarily affect birds are able to adapt to mammals, a topic that Kawaoka and his colleagues at UW–Madison’s Influenza Research Institute investigate since such a jump could trigger an influenza pandemic. Like other influenza viruses, H5N1 viruses mutate at a relatively rapid clip as they infect new hosts. Sometimes these mutations allow the viruses to more easily infect and spread among new species. That’s how the current viruses, which have been infecting birds around the world in recent years, began to spread among mammals, most notably North American dairy cattle in 2024. Kawaoka and his collaborators found that the H5N1 virus that infected the Texas dairy worker included a mutation that the team first identified in 2001 as important for causing severe disease. Luckily, Kawaoka says, the strain with that mutation seems to have died out. “This isolate is unique among the H5N1 viruses circulating in cows,” he says. Kawaoka hypothesizes that H5N1 viruses took two paths when they made the jump from birds to cows, both facilitated by mutations that made the virus better adapted to mammals.

Kawaoka and his colleagues suggest that one path resulted in the more concerning mutation found in the Texas dairy worker, while the other led to a less dangerous mutation in the same protein. “Both mutations give the virus the ability to adapt to mammals, but the good thing is the one containing this more pathogenic mutation has not been detected again,” Kawaoka says. “So there are no extremely pathogenic H5N1 viruses currently circulating in cows. However, if a currently circulating cow H5N1 virus acquires that mutation, then that would be an issue.” Whether a virus with such a mutation would be dangerous for humans remains to be seen. “The puzzling thing is why the human who got this virus did not have a severe infection,” says Kawaoka, noting a few possibilities. Perhaps exposure to seasonal influenza viruses provides some level of protection via antibodies, or maybe the route of infection is important; the Texas dairy worker’s main symptom was conjunctivitis, suggesting the virus entered through the eye rather than the more typical respiratory route. Alternatively, more robust surveillance of influenza cases among American dairy workers since the virus began spreading on farms might mean more cases — including mild ones — are being identified. Another possibility is this particular strain might simply be less severe in humans than mammals like ferrets. “Those are all possibilities, but we don’t know,” says Kawaoka. “So, we’re now trying to understand why this virus is so pathogenic in ferrets and what that could mean for human infections.”

Published in Nature (Oct. 28, 2024):

https://doi.org/10.1038/s41586-024-08254-7 

H5Nx viruses continue to wreak havoc in avian and mammalian species worldwide. The virus distinguishes itself by the ability to replicate to high titers and transmit efficiently in a wide variety of hosts in diverse climatic environments. Fortunately, transmission to and between humans is scarce. Yet, if such an event were to occur, it could spark a pandemic as humans are immunologically naïve to H5 viruses. A significant determinant of transmission to and between humans is the ability of the influenza A virus hemagglutinin (HA) protein to shift from an avian-type to a human-type receptor specificity. Here, we demonstrate that a 2016 2.3.4.4e virus HA can convert to human-type receptor binding via a single Q226L mutation, in contrast to a cleavage-modified 2016 2.3.4.4b virus HA. Using glycan arrays, x-ray structural analyses, tissue- and direct glycan binding, we show that L133aΔ and 227Q are vital for this phenotype. Thus, whereas the 2.3.4.4e virus HA only needs a single amino acid mutation, the modified 2.3.4.4b HA was not easily converted to human-type receptor specificity.

Preprint in bioRxiv  (Jan. 11, 2025):

https://doi.org/10.1101/2025.01.10.632119 

A raw milk maker who is now prohibited from distributing his product after California regulators found multiple instances of bird flu contamination believes he is the target of a political witch hunt. California has suspended Raw Farm, LLC from distributing all “raw milk, cream, kefir, butter and cheese products” made from November 27 onwards” after bird flu was detected in multiple raw milk products in stores and at bottling sites, state regulators said. The move comes after bird flu was detected in their product last week. Raw Farms CEO Mark McAfee is adamant that his milk poses no threat, and told The Post he is working to source milk from cows outside his region where bird flu has not spread. While McAfee contends the quarantine is the result of “political forces” that are on a “warpath” against raw, unpasteurized milk. “For the last 40 years the FDA has hated raw milk. There is Bizarre crazy suppression of raw milk anywhere any way they can do it,” he told The Post. Raw Farm is also voluntarily pulling all of its raw milk and cream products off store shelves after the bird flu contamination was detected, the California Department of Public Health said in a statement. The recall applies to all raw milk and dairy products produced between November 9 and November 27.

State regulators urged consumers to the “immediately return any remaining product to the retail point of purchase,” and to “avoid consuming any Raw Farm products for human consumption.” Despite the recall and quarantine, the California Department of Public Health said that there have been “no human bird flu cases associated with [Raw Milk] have been confirmed to date.” “There are no illnesses associated with H5N1 [bird flu] in our products, but rather this is a political issue. We are working towards resolving this political issue while being cooperative with our government and regulatory agencies,” Raw Farm said in a statement on its website. Raw milk is animal milk that has not been pasteurized and can carry diseases such as Salmonella, E. coli and Listeria, according to the FDA. “Bird flu virus levels have been demonstrated to be high in raw milk from infected cows, and sporadic human cases identified in workers in close contact with infected dairy cows and their milk indicate that raw milk is infectious to humans,” the agency said. Bird flu symptoms include cough, runny nose, diarrhea body ache and vomiting when contracted by humans, according to the agency. California has had 31 people contract bird flu since October, all but one of whom had come in direct contact with dairy cows infected with the virus, the statement claims. There has not been any recorded human-to-human transfer of bird flu anywhere in the US, and the overall public risk “public remains low,” the agency said.

New Zealand has ceased all poultry exports from its commercial rural Otago egg farm, after tests confirmed a “high pathogenic” strain of avian influenza in chickens. Notably, the viral strain differs from those responsible for the recent H5N1 (US) and H7 outbreaks in the US and Australia, respectively, confirms Biosecurity New Zealand. The move is expected to halt the exports of poultry products worth about NZ$190 million (US$112 million) a year until the country announces it is free of bird flu, according to Food Safety Minister Andrew Hoggard. Tests from the Mainland Poultry managed farm identified the bird flu strain as the H7N6 subtype of avian influenza, which is closely related to low pathogenicity (HPA1) strains present in wild birds in the country. The outbreak may be a “spillover event,” where laying hens who were foraging outside of the shed were exposed to a low pathogenic virus from wild waterfowl,” explains Stuart Anderson, deputy director-general of Biosecurity New Zealand. “Low pathogenic viruses are present in wild birds here, especially waterfowl like ducks, geese, and swans, and the virus can mutate on interaction with chickens.” Amid ongoing human transmission concerns in other bird flu cases, especially farmers, Anderson assures that the strain found on the New Zealand farm is “not a wildlife-adapted strain like H5N1, so we believe it is unlikely to be transmitted to mammals.”

Ensuring food safety

According to Biosecurity New Zealand, there are no reports of ill or dead birds on other poultry farms and “no human health or food safety concerns.” It suggests consuming “thoroughly cooked” egg and poultry products by heating food to an internal temperature of 75°C for at least 30 seconds, or 70°C for three minutes or 65°C for 15 minutes.

Government action

The government is taking “quick action” along with Mainland Poultry and has issued a restricted place notice. “Test results late last night confirmed the strain, but we already had restrictions in place and expert biosecurity staff on site, with more arriving today.  Mainland Poultry took the right steps by reporting ill birds in one shed on the property and locking that building down as testing continued,” says Anderdon. Biosecurity New Zealand has placed a 10 km buffer zone around the farm, with restrictions preventing animal movement, equipment and feed movement. John McKay, chief executive of Mainland Poultry, which manages the free-range farm, says international experience with avian influenza has proven that H7N6 can be eradicated “quickly and successfully.” “We will be working closely with MPI (Ministry for Primary Industries) to depopulate the affected shed, ensure rigorous testing of all other birds on the farm and manage the situation effectively.” The farm has strong biosecurity standards and Mainland is helping the MPI with ongoing investigation and tracing animal movements. It suggests farmers to contact a veterinarian if they notice poultry or domestic birds exhibiting signs of HPAI, to rule out more common avian diseases. All content and features on this website are copyrighted with all rights reserved. The full details can be found in our privacy statement

Since the emergence of highly pathogenic avian influenza virus (HPAIV) H5N1 of clade 2.3.4.4b as a novel reassortant virus from subtype H5N8, the virus has led to a massive number of outbreaks worldwide in wild and domestic birds. Compared to the parental HPAIV H5N8 clade 2.3.4.4b, the novel reassortant HPAIV H5N1 displayed an increased ability to escape species barriers and infect multiple mammalian species, including humans. The virus host range has been recently expanded to include ruminants, particularly dairy cattle in the United States, where cattle-to-cattle transmission was reported. As with the avian 2.3.4.4.b H5N1 viruses, the cattle-infecting virus was found to transmit from cattle to other contact animals including cats, raccoons, rodents, opossums, and poultry. Although replication of the virus in cows appears to be mainly confined to the mammary tissue, with high levels of viral loads detected in milk, infected cats and poultry showed severe respiratory disease, neurologic signs, and eventually died. Furthermore, several human infections with HPAIV H5N1 have also been reported in dairy farm workers and were attributed to exposures to infected dairy cattle. This is believed to represent the first mammalian-to-human transmission report of the HPAIV H5N1.

Fortunately, infection in humans and cows, as opposed to other animals, appears to be mild in most cases. Nevertheless, the H5N1 bovine outbreak represents the largest outbreak of the H5N1 in a domestic mammal close to humans, increasing the risk that this already mammalian adapted H5N1 further adapts to human-to-human transmission and starts a pandemic. Herein, we discuss the epidemiology, evolution, pathogenesis, and potential impact of the recently identified HPAIV H5N1 clade 2.3.4.4b in dairy cattle in the United States. Eventually, interdisciplinary cooperation under a One Health framework is required to be able to control this ongoing HPAIV H5N1 outbreak to stop it before further expansion of its host range and geographical distribution.

Published (Nov.13, 2024):

DOH investigating and urging public to be vigilant of symptoms. DOH did not immediately provide the location of the site. Officials say the specimen was collected on Nov. 7 and DOH received the result Tuesday. H5N1, also called Highly Pathogenic Avian Influenza (HPAI) is one type of H5 avian influenza. DOH says they’re unable to confirm if this detection is HPAI and say further investigation is needed. A nationwide outbreak of H5N1 has been spreading among birds and mammals, but officials says there’s no evidence of sustained human-to-human transmission of H5N1 in the United States. DOH says Hawaii has been the only state without H5N1 detected in birds or animals and there are no reports of human or animal H5N1 cases in Hawaii. Hawaii health officials reassure the overall risk of H5N1 statewide remains low.  DOH says they will partner with federal agriculture and wildlife agencies for further investigation, prevention, and public health surveillance efforts. With the possible detection, DOH provided “best-practice” guidance for interacting with animals and consuming animal products:

• In general, do not touch birds, livestock, or wild animals that are sick or dead without personal protective equipment.
• Residents are encouraged to report sick pets to their veterinarian. In addition, please contact the Animal Industry Division at Hawaii Department of Agriculture at 808-483-7106, Monday to Friday from 7:45 a.m. to 4:30 p.m., or 808-837-8092 during non-business hours and holidays to report multiple or unusual illnesses or deaths in poultry, livestock, or wild birds or animals.
• Do not touch or consume raw milk or raw milk products, especially from animals with confirmed or suspected avian influenza infection. Pasteurized milk products are safe.

Symptoms of avian influenza may include fever, cough, sore throat and conjunctivitis. Antiviral flu treatment is recommended as soon as possible. Contact the Department of Health at 808-586-4586 immediately if you believe you have contracted H5N1 or been in close contact with sick or dead animals.

A teenager in British Columbia, Canada has been hospitalized with a presumed case of H5N1 bird flu, the first detected human case in the country from the recent outbreak. The individual is presumed to have contracted the virus, also called avian flu or avian influenza, from exposure to wild birds, but testing is ongoing to confirm this. “Our thoughts are with this young person and their family during this difficult time,” said Dr. Bonnie Henry, B.C.’s provincial health officer in a news release. “This is a rare event, and while it is the first detected case of H5 in a person in B.C. or in Canada, there have been a small number of human cases in the U.S. and elsewhere, which is why we are conducting a thorough investigation to fully understand the source of exposure here in B.C,” said Henry. All close contacts of the infected individual are being contacted and investigations are underway to figure out how the teenager was infected. Canada has been testing wild birds, finding strains of the virus similar to those circulating in both parts of the U.S. and Japan, but this is the first time the virus has been found in a human. The case represents only Canada’s second ever detected case of H5N1, after a traveller returning from China in 2014 died from the disease.

Since March 2024, the U.S. department of agriculture has confirmed outbreaks in 440 dairy cattle herds across 15 states, with the outbreak continuing. The virus has also been detected in 45 commercial poultry flocks and 30 backyard flocks. Canada has been testing milk and livestock, but unlike in the U.S. there has been no confirmed cases of the same H5N1 virus from the U.S. in either cattle or poultry farms in Canada. According to the World Health Organization, 903 cases of H5N1 in humans have been detected since 2003 across five countries. Of these cases, 464 were fatal, resulting in a fatality rare of 51%. However, this is likely to be an overestimate as individuals who are more sick are more likely to be hospitalized and be tested for H5N1. Many of the symptoms of H5N1 overlap with other viral infections such as influenza and Covid-19, meaning people may not know they are infected with H5N1. The first case of the current dominant H5N1 strain in humans in the U.S. was detected in April 2024, with 44 cases in total now detected, according to the U.S. CDC. These cases are thought to mostly come from either contact with infected dairy cows, poultry farms or wild birds. However this number is likely to be a significant underestimate, with many cases likely to go undetected. Earlier this month, the virus was detected in wastewater testing in a Los Angeles County, suggesting that infections in humans may be far more prevalent than believed.

Background
Highly pathogenic avian influenza (HPAI) H5Nx and human H1N1pdm2009 influenza viruses can infect cats. Infections in cats may result in viral adaptations or recombinant viruses, which may facilitate zoonotic transfer.

Aim
We aimed to investigate the presence of HPAI H5 clade 2.3.4.4 and H1 influenza viruses and antibodies to these viruses in domestic and rural stray cats in the Netherlands and factors associated with exposure.

Methods
Sera from stray and domestic cats, sampled 2020–2023, were analysed by ELISA and confirmed by hemagglutination inhibition assay (HAI) and pharyngeal swabs and lung tissue for influenza A virus by RT-qPCR.

Results
In 701 stray cats, 83 (11.8%; 95% confidence interval (CI): 9.5–14.5) sera were positive for HPAI H5 and 65 findings were confirmed. In HAI, two sera were positive for both HPAI H5 and H1. In 871 domestic cats, four (0.46%; 95% CI: 0.13–1.2) sera were HPAI H5 positive and none were confirmed but 40 (4.6%; 95% CI: 3.3–6.2) sera were seropositive for H1 and 26 were confirmed. Stray cats living in nature reserves (odds ratio (OR) = 5.4; 95% CI: 1.5–20.1) and older cats (OR = 3.8; 95% CI: 2.7–7.1) were more likely to be HPAI H5 seropositive. No influenza A virus was detected in 230 cats.

Conclusion
The higher HPAI H5 seroprevalence in stray cats compared with domestic cats suggests more frequent viral exposure, most likely due to foraging on wild birds. In contrast, exposure to H1 was more common in domestic cats compared with stray cats.

The most important tool in our arsenal is widespread testing, write Janika Schmitt and Michael Mina. We're not doing enough of it. If H5N1 turns into a full-blown pandemic, we are currently in chapter one. To prevent chapter two from becoming a reality, the most important tool in our arsenal will be widespread testing. Testing isn’t just about diagnosing people with the virus. Containing the spread of this highly pathogenic bird flu strain in cattle hinges on our ability to detect and track it. The H5N1 outbreak in dairy cows is widespread and spans multiple U.S. states. Although only one human infection with the virus has been documented, more infections are likely going undetected. Most importantly, unchecked transmission among cattle means the virus is increasingly bumping up against humans. Every human exposure, in turn, provides an opportunity for new mutations that could enable human-to-human transmission. The U.S. Centers for Disease Control and Prevention (CDC) maintains that as of now, the risk to the general public from H5N1 remains low. And indeed, it is entirely possible H5N1 might never turn into a human pandemic. However, being wrong would be incredibly costly.  We find ourselves in a situation reminiscent of early 2020, when the U.S. stood on the brink of the COVID-19 pandemic and hesitated to take decisive action, restricting testing to only those with epidemiological links to China. Scientists estimate that by early March 2020, less than 1% of SARS-CoV-2 infections in the U.S. were detected by testing. We effectively flew blind straight through chapters one and two of the COVID-19 pandemic.

Today, genomic analyses tell us that bird flu had been circulating in dairy cows for at least four months before it was detected in March 2024. The delay was despite early warning signs of infections on dairy farms in February. The U.S. government cannot afford to repeat the mistakes made at the onset of the COVID-19 pandemic. Though the risk of an H5N1 pandemic may currently be low, the consequences of inaction could be catastrophic, and the benefits of proactive testing far outweigh the short-term costs. Despite the high stakes, government action initially has been slow and uncoordinated. Until mid-April, testing was not only voluntary but restricted to symptomatic animals, with limits on the number of tests per farm. A complicating factor is that responsibility for outbreak control is divided between three federal agencies: the U.S. Department of Agriculture (USDA) for livestock, the U.S. Food and Drug Administration (FDA) for food safety, and the CDC for human health and surveillance. Yet by May, the CDC was aware of only about 30 people who had been tested for bird flu. The CDC has been monitoring data from emergency departments in areas where H5N1 has been found in cattle and has found nothing unusual so far. But if and when infected people show up at the ER, it will be way too late to contain the outbreak at its source. We must stop flying blind. Regular and widespread testing is our only way to detect H5N1 and stop the virus from spreading. The recent federal order requiring mandatory testing of dairy cows before they cross state lines is a step in the right direction. But we could be doing more: we should incentivize testing, rather than restricting it. A layered testing strategy that combines waste or wastewater surveillance on the farms, routine testing of pooled milk from the cows, and active surveillance testing of animals and humans—including those without symptoms—is our best hope of stopping the virus from spreading. The tools and infrastructure for such a testing regimen are already at our fingertips. During the pandemic, the U.S. government spent billions supporting testing and creating an extensive biosurveillance infrastructure. Influenza monitoring via wastewater surveillance has already shown increases in the H5 subtype—the viral group to which H5N1 belongs. In 2024, labs across the U.S. now have PCR machines sitting idle, waiting to be turned back on. And U.S. test manufacturers have efficient automated manufacturing lines capable of producing millions of rapid tests a day.

For animal testing, we should accelerate evaluations of both laboratory and point-of-need tests. Testing should include cows, but also pigs, which are known “mixing vessels” for viruses across host species. We should also evaluate different specimens like swabs and cow milk, including the pooling of samples to test more efficiently. If existing influenza A rapid tests could detect the virus from a drop of contaminated milk, it would be a game changer. Given the sky-high virus loadsdetected in milk from infected dairy cows, it is possible that a single drop could be enough. But if the tests need to be tweaked, the USDA and FDA should be funding studies to do so now. With H5N1 circulating in herds nationwide, we can quickly assess the effectiveness of these tests and refine our strategies accordingly. When it comes to human testing, it is laudable that the CDC is now engagingwith test manufacturers to develop a widely available H5N1 test. In the meantime, existing authorized rapid tests for influenza A will likely detect H5N1. To confirm, the CDC, FDA, and the National Institutes of Health’s Rapid Acceleration of Diagnostics (RADx) program should support evaluations that close that knowledge gap. If these broad influenza rapid tests detect H5N1, we could send any positive influenza A test to a lab for confirmation and evaluation of H5N1 or another virus. This surveillance testing algorithm, which leverages broad influenza tests for initial screening and reserves more specific H5N1 assays for confirmation, followed by rapid sequencing of positives, would allow us to allocate our public-health resources with maximum efficiency. The rapid turnaround times of point-of-need tests would enable infected people to immediately isolate themselves and get influenza antivirals, minimizing the risk of transmission.

The federal government keeps the influenza antiviral Tamiflu as well as personal protective equipment (PPE) in its Strategic National Stockpile. To ensure that tests are similarly available, the government must send a clear demand signal to manufacturers, committing to purchase a substantial quantity of tests, just as they do for antivirals and PPE. This would give manufacturers the confidence needed to ramp up production and create a robust national stockpile. Congress should allocate funding to support these efforts, with the White House’s new Office of Pandemic Preparedness and Response coordinating a unified response across the CDC, USDA, and FDA.  The government must also address the stigma associated with positive test results and provide financial aid and resources to help affected farmers and their workers. Many of the individuals working on dairy farms are undocumented, for example. The current administration should make assurances that offer protection to undocumented workers who agree to test as a part of public-health surveillance testing programs. Success in public-health prevention is difficult to spot, and success in preventing a pandemic can be misconstrued as a failure or a misappropriation of funds. It’s nearly impossible to recognize the absence of a pandemic that never happens, but would have if not for aggressive and early efforts. However, tracking detections and documenting actions taken will help. The cost of inaction far outweighs the cost of prevention. We risk losing all the lessons learned from COVID-19 if we don't apply them now. The good news is that we have the tools to prevent an H5N1 pandemic at hand. But we must be willing to use them, and fast.

The USDA said the Oregon farm has been quarantined to prevent the spread of the virus and there are no concerns about the safety of the nation's pork supply. A pig in Oregon has tested positive for the H5N1 bird flu virus, the Agriculture Department said Wednesday. It's the first time the virus has been detected in swine in the United States. Test results are pending for two other pigs found on the farm in Crook County, Oregon, the USDA said, while two others tested negative. The pig that tested positive didn't show signs of illness. The five pigs were tested for H5N1 out of an abundance of caution, officials said, and "because of the presence of H5N1 in other animals on the premises." The case is concerning as pigs can become infected with both bird and human viruses at the same time, which can give rise to mutated strains that can more easily infect humans. Officials said there are no concerns about the safety of the nation's pork supply. The farm is noncommercial, the USDA said, and the animals weren’t intended for the commercial food supply. Additionally, the farm has been quarantined to prevent the spread of the virus. Sheep, goats and other animals on the farm are under surveillance, officials said.The update comes as the H5N1 virus continues to spread rapidly among dairy cows across the country. 

The bird flu outbreak in dairy cows has infected 387 herds across 14 states so far, according to the Centers for Disease Control and Prevention. Since March, there have been a total of 36 human cases, the majority of whom had direct contact with farm animals, such as dairy cows and poultry. Most cases have been reported in California and Colorado. All of the patients who had tested positive have recovered. Most had redness and discharge from the eyes, and some had mild respiratory symptoms. There is no indication yet that this strain of flu virus is mutating in ways that would allow it to spread easily among people. Last week, the CDC released results of a monthslong investigation that found no evidence of bird flu spreading from human to human. It's unclear how the pig in Oregon was exposed to bird flu, although earlier this month state officials detected the virus in poultry on the farm. Officials said livestock and poultry on the farm shared water sources, housing and equipment. In other states, officials said, the combination has enabled transmission between species. 

APHIS Press Release (Oct. 30, 2024):

https://www.aphis.usda.gov/news/agency-announcements/federal-state-veterinary-agencies-share-update-hpai-detections-oregon