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New federal rules aimed at limiting the spread of the H5N1 bird flu virus among dairy cattle go into effect Monday, but detailed guidance documents released Friday by the U.S. Department of Agriculture reveal its mandatory testing order is less stringent than initially described.
While that is easing concerns from farmers and veterinarians about the economic and logistical burden of testing, it leaves questions about how effective the testing program will be at containing additional outbreaks.
More testing is better, said Jennifer Nuzzo, an epidemiologist and director of Brown Universitys Pandemic Center. But in many ways this policy is very leaky in terms of how much virus it will allow to move. And because we still dont know whats driving transmission between cows, we should not pin our hopes on this policy making a major dent in the infections were seeing.
On Wednesday, the USDA issued a federal order requiring farms to ensure lactating dairy cows test negative before being moved across state lines. Laboratories and state veterinarians also must report to the USDA any animals that have tested positive for H5N1 or any other influenza A virus. The guidance issued Friday narrowed the scope of that order.
It says farmers only have to test up to 30 animals in a given group. The guidance does not say how farmers should determine which 30 animals to test in larger groups that are being readied to be moved. The USDA did not respond to STATs questions about the rationale for the 30-animal cap.
Jamie Jonker, chief scientific officer for the National Milk Producers Federation, said the group supports the testing program as an important step in response to the outbreak, one that dairy farmers are ready to take as part of their responsibility to ensure the safety of their animals and the milk supply.
While pragmatic, researchers who spoke to STAT were split on whether the policy will be effective. Anice Lowen, an influenza researcher at Emory University School of Medicine, told STAT via email that the approach is likely sufficient to detect an H5N1-positive herd. I think this approach is reasonable, she said.
Nuzzo had concerns, however, that in very large herds, like those around 500 or more, infected animals could be missed. In herds where outbreaks have occurred, only somewhere between 5% to 15% of cows have presented with clinical symptoms, Terry Lehenbauer, a bovine disease epidemiologist and director of the Veterinary Medicine Teaching and Research Center at UC Davis, told STAT. My general experience would suggest that there are not a lot of lactating cattle that get shipped interstate on a regular basis, so were probably looking at fairly small numbers of animals that will be required, he said.
The federal order is in recognition of epidemiological evidence that the virus is spreading between cows in affected herds and between herds as cattle are moved. As of April 26, H5N1 outbreaks have been confirmed in 34 dairy herds in nine states, with the first outbreak in Colorado reported Friday.
But analysis of viral genomes from cows infected with H5N1, combined with evidence that genetic traces of the virus have been found broadly in milk in grocery stores, indicate that the outbreak is much more widespread.
The risk of infection from ingesting milk is believed to be very low because pasteurization should kill the virus. Academic researchers did not find any live virus in a small study of commercial milk products. The U.S. Food and Drug Administration is conducting its own, much larger study on the viability of virus in milk, results from which are expected in the coming days. On Friday, the FDA issued an update saying that tests of several samples of retail powdered infant and toddler formula were negative, indicating no presence of H5N1 viral fragments or whole virus. It provided no details on the quantity tested.
Because farmers are required to divert milk from sick animals out of the national food supply, the traces of H5N1 in grocery store products indicates that asymptomatic animals may also be shedding the virus. In an FAQ posted online Thursday, the USDA confirmed that cows without signs of illness can still test positive for virus, acknowledging it had found H5N1 in the lungs of an asymptomatic cow in an affected herd.
Under the new rules, cows that are to be moved between states must have samples collected and tested no more than a week prior to transport. A licensed or accredited veterinarian has to collect the samples between 3 and 10 milliliters of milk per animal taken from each of the four teats. Thats very important, the USDA noted, because there have been reports of infected animals having virus in only one teat.
A strange feature of H5N1s jump from birds into cows is that the virus seems to have developed an affinity for mammary tissue. Samples from sick cows show the highest levels of virus not in their noses but in their milk, suggesting that udders seem to be where H5N1 migrates to or infects.
The USDA order does not apply to beef cattle or non-lactating dairy cattle, including calves, due to their lower risk profile, according to the guidance. But influenza researchers told STAT that not enough yet is known about the risks to non-lactating animals to leave them out. Testing such cattle destined to move between states would not only guard against interstate spread of the virus, it would give important insight into the susceptibility of non-lactating animals, Lowen said.
Thijs Kuiken, a professor of comparative pathology in the Department of Viroscience at Erasmus Medical Center in Rotterdam, is particularly concerned about the potential for milk from infected cows to harm calves. The U.S. Food and Drug Administration has encouraged farmers to discard milk from H5N1-positive cows, but if thats not possible and farmers intend to feed calves with that milk, they should first heat it to kill any viruses and bacteria.
Newborn calves need to consume colostrum, the antibody-rich milk cows produce in the first few days after birth, in order to start building their immune systems to ward off all the microbial threats that exist on a farm. Without it, calves often quickly succumb to infection.
If a farmer doesnt know that a cow has H5N1 because its not showing symptoms, calves could inadvertently be consuming the virus. The reason that has Kuiken worried is because of a cluster of fatal H5N1 cases in baby goats, reported in Minnesota in March. Genomic analyses showed they likely contracted the virus from a backyard poultry flock that had been depopulated due to H5N1 days before the goats were born. The animals had shared the same enclosure, including a water source that was likely contaminated. Ten of the kids died after showing neurological symptoms; necropsies on five of them showed virus in the brains and other organs.
Because we dont know the extent of this virus in dairy herds in North America, Kuiken said, I would expect there will be neurologically affected calves turning up sometime. My prediction is that if it has not already happened, that young dairy calves on affected farms will be found with severe highly pathogenic avian influenza H5N1 infection.
At this time, there have been no reported cases of H5N1-positive dairy cattle exhibiting any signs of neurological disease in the U.S.
Correction: An earlier version of this article misspelled Thijs Kuikens surname.
Helen Branswell contributed reporting.
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Cattle testing for H5N1 bird flu will be more limited than USDA initially announced - STAT
Public health officials are continuing to monitor as an outbreak of avian flu, also known as bird flu, continues to spread across the country.
The strain, known as H5N1, has sickened several mammals this year, according to the Centers for Disease Control and Prevention (CDC), the U.S. Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA).
Several dairy cows have been infected, resulting in milk samples showing inactive remnants of the virus, and one human case has been confirmed.
Health officials say the food supply is safe and the risk to the general public is currently low.
Here's the latest to know on the outbreak.
Avian influenza, or bird flu, is an infectious viral disease that primarily spreads among birds and is caused by infection with Influenza A viruses.
These viruses typically spread among wild aquatic birds but can infect domestic poultry and other bird and animal species, according to the CDC.
Although bird flu viruses normally don't infect humans, there have been rare cases of infection. To confirm infection, laboratory testing is required.
Signs and symptoms of infection in humans often include sore throat, cough, fever, runny or stuffy nose, headache, muscle or body aches, fatigue and shortness of breath. Less common symptoms include nausea, vomiting, diarrhea and seizures.
Infections can range from no symptoms or mild illness, such as flu-like symptoms, to more severe illness, such as pneumonia that could require hospitalizations, the CDC says.
In early March, the USDA announced a bird flu strain that had sickened millions of birds across the U.S was identified in several mammals this year.
At the time, three states had reported cases of bird flu in mammals in 2024, including striped skunks found in Washington state, a mountain lion in Montana and a raccoon in Kentucky.
A few weeks later, federal and state public health officials said they were investigating an illness among primarily older dairy cows in Kansas, New Mexico and Texas and causing symptoms including decreased lactation and low appetite.
The USDA said in a statement at the time that "there is no concern about the safety of the commercial milk supply or that this circumstance poses a risk to consumer health."
Earlier this month, the CDC said a human case of bird flu was identified in Texas and linked to cattle. The infected individual worked directly with sick cattle and reported eye redness as their only symptom.
This is the second human case of H5N1 ever reported in the U.S. but the first linked to cattle.
However, there have been no reports and no evidence to indicate there is person-to-person transmission, a CDC Director Dr. Mandy Cohen told ABC News at the time.
The CDC said it considers the health risk assessment to the general public to be low.
Earlier this week, reports emerged of bird flu fragments found in samples of pasteurized milk. However, the fragments are inactive remnants of the virus and cannot cause infection as the commercial milk supply undergoes pasteurization.
Federal agencies maintain the U.S. commercial milk supply remains safe because milk is pasteurized and dairy farmers are required to dispose of any milk from sick cows, so it does not enter the supply.
"To date, we have seen nothing that would change our assessment that the commercial milk supply is safe," the FDA said in an update.
The FDA said in its update that fragments of the virus are likely inactivated by the pasteurization process.
"The discovery of bird flu virus fragments in commercial milk is significant, not because it poses a direct threat to public health, but because it indicates a broader exposure among dairy cattle than we previously understood," said Dr. John Brownstein, an epidemiologist and chief innovation officer at Boston Children's Hospital and an ABC News contributor. "This calls for an expanded surveillance of both the virus's presence and its potential impact on food safety."
He added, "It's crucial to continue rigorous testing to determine if any live virus can survive the process. Understanding the dynamics of this virus in dairy products will help us refine our risk assessments and ensure public health safety."
The FDA said it is collaborating closely with the CDC's food safety group surveillance team to monitor emergency department data and flu testing data for any unusual trends in flu-like illness, flu or conjunctivitis. There is currently no data showing any unusual trends or activity.
ABC News Sony Salzman contributed to this report.
Read more from the original source:
In mid-March, a mysterious disease began to spread among cows at a north Texas dairy farm. Just a few days later, cats on the farm started acting strange.
Their eyes and noses leaked copiously, they walked incessantly in circles, their bodies grew stiff, and they lost their sight and coordination. Then, they began to die.
According to officials at the US Centers for Disease Control and Prevention (CDC), a dozen of the domestic felines on this one farm were the casualties of a highly contagious strain of bird flu. They seem to have contracted the virus from drinking raw, unpasteurized milk from cows on the property.
The cats are merely the latest victims in a continued outbreak of bird flu, which first entered the US in late 2021, and has since jumped from birds to mammals, such as foxes, raccoons, possums, skunks, seals, leopards, bears, mountain lions, and bobcats.
On March 25, the US Department of Agriculture reported the first confirmed case of bird flu ever identified among cows.
Several dairy farms in Kansas and Texas were affected, and later, their cows carried the virus to Michigan, Idaho, and Ohio when they were transported interstate.
Despite one farm worker falling ill from the virus through contact with the cows, so far this outcome is extremely rare. Little more than a handful of cases of this bird flu strain have infected humans worldwide and only one of these cases is likely to have involved mammal to human transmission, not bird to human transmission.
Officials have assured the public that drinking pasteurized dairy milk will not expose them to the virus. The Food and Drug Agency is carrying out extensive milk product tests, and it has detected no signs of the virus as of yet.
Unfortunately, the dozen or so domestic cats that died on the dairy farm in north Texas contracted the virus before farmers knew what pathogen they were dealing with. Unknowingly, they fed their cats contaminated milk.
Cows in the US that are sick with bird flu are producing thick and syrupy milk, but perhaps this symptom isn't as apparent in the early days of illness.
The first cat to show signs of sickness on the north Texas dairy farm was recorded a mere day after the first cow fell ill.
On March 21, samples of cow milk from the affected dairy farms and two deceased cats from these farms were donated to a diagnostic lab at the Iowa State University (ISU). The cats tested positive for the influenza A virus (IAV).
Cases of bird flu among cats are globally well-documented. Our feline pets are especially susceptible to the virus when in contact with sick birds, but the transfer from cows has never been previously reported.
Researchers at ISU say the cow and cat samples they analyzed contained signs of IAV with "a notable degree of similarity", which suggests a "shared origin" for the strain.
"Although exposure to and consumption of dead wild birds cannot be completely ruled out for the cats described in this report, the known consumption of unpasteurized milk and colostrum from infected cows and the high amount of virus nucleic acid within the milk make milk and colostrum consumption a likely route of exposure," write the team of researchers, led by pathologist Eric Burrough.
The findings suggest bird flu can jump from mammal to mammal, which may make the contagion harder to control. Even among cows, experts still aren't sure how the virus is transmitted.
As the public waits for more answers, one thing is clear: pasteurized milk is the safest option of all. For both humans and cats.
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Bird Flu in Raw Cow Milk Has Killed Farm Cats in a Concerning First - ScienceAlert
A senior official from the US Food and Drug Administration (FDA) said today that its nationwide survey of retail milk has found remnants of H5N1 avian flu viruses in one in five samples, with the highest concentrations in regions where outbreaks in dairy cattle have been reported.
Donald Prater, DVM, acting director of the FDA Center for Food Safety and Applied Nutrition (CFSAN), shared the new findings with state health officials who took part in a scientific symposium on H5N1 hosted by the Association of State and Territorial Health Officials (ASTHO). The results come in the wake of earlier findings this week from more limited FDA sampling, along with similar findings from a smaller set of samples tested by a lab that's part of the National Institute of Allergy and InfectiousDiseases Centers of Excellence for Influenza Research and Response (CEIRR) Network.
At today's ASTHO briefing, state health officials heard the latest investigation and research updates from federal health officials and had the opportunity to ask their own questions, everything from virus shedding in cow manure to pandemic preparedness.
Prater reiterated that the FDA hasn't changed its assessment that the nation's milk supply remains safe. So far, early work on milk samples that were positive for H5N1 fragments haven't found any viable (potentially infectious) virus.
He said, however, that the FDA still has a long list of data gaps to fill, including identifying the risk of infection to humans via oral consumption and validating that existing pasteurization methods can inactivate H5N1.
Other data gaps include how long the virus survives in raw milk and the infectious dose of viruses. Though a major concern is retail milk, Prater also said the FDA needs to see if contamination is occurring in other products, such as cheese made from raw milk.
Rosemary Sifford, DVM, deputy administrator for veterinary services and chief veterinarian with the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) said the agency has now shared 260 genetic sequences with public databases, up from 239 earlier this week. Of those, only 1 had a mutation linked to mammalian adaptation.
She also said the B3.13 genome circulating in cattle was first seen in poultry in the middle of March in a Texas flock at a time when the virus was cropping up in some of the state's dairy farms. Sifford said investigators continue to look at how the virus is moving on farms and how it transmits among cattle.
Scientists are looking for the virus in other species, including feral pigs, and regular influenza surveillance is monitoring the situation in commercial pigs. Sifford said efforts are under way to gauge how long infected cows shed the virus and if shedding patterns are any different in asymptomatic animals.
When asked about on-farm transmission, she said scientists haven't observed significant shedding in cow feces. Meanwhile, sampling from the USDA's Food Safety and Inspection Service (FSIS) found the highest concentrations in milk and mammary tissue.
Centers for Disease Control and Prevention (CDC) officials shared more details from their epidemiologic investigations, including virus findings in other animals on affected dairy farms. Sonja Olsen, PhD, associate director for preparedness and response with the CDC's Influenza Division, said there were 6 H5N1 positive tests in cats from three states: 3 in Texas, 2 in New Mexico, and 1 in Ohio.
Also, there were 5 H5N1 detections in wild birds on the farms.
She said CDC a key question is the infection risk from exposure to milk and whether certain conditions, such as aerosolization, pose a higher risk.
Vivien Duggan, PhD, who heads the CDC's Influenza Division, said the interagency Flu Risk Management group, which formed 15 years ago, is meeting now to discuss prepandemic vaccines and diagnostics.
On the research front, the CDC is looking for any changes in the virus that would hamper the ability to use countermeasures, such as antiviral drugs and vaccines.
A key tool that the CDC uses to evaluate and prioritize resources is the Influenza Risk Assessment Tool (IRAT), in which its experts grade the virus using 10 data criteria. Duggan said the CDC is still gathering some data and that it will take some time to evaluate the virus and come up with a risk score. In its last assessment in July 2023, the agency scored the H5N1 clade 2.3.4.4b virus from a Spanish mink farm outbreak as slightly higher for some elements than a 2022 virus from the same clade from wild birds.
So far, research results have been promising for antiviral susceptibility. And for the two candidate vaccine viruses against the H5N1 2.3.4.4b clade, experiments using ferret antisera show good cross-reaction against the outbreak strain, she said.
When state officials asked what would trigger ramped up H5N1 vaccine production, Duggan said officials are watching for certain cues, such as change in mammalian transmission, better adaptation to human-to-human spread, and clusters of cases. "There's no formula, but we're all on the watch."
Health officials also heard from government countermeasure experts, who said they don't foresee any issues with the antiviral supply chain.
State health officials had several questions about where things stand with a candidate vaccine. David Boucher, PhD, director of infectious disease preparedness and response at the Department of Health and Human Services Administration for Strategic Preparedness, said there is a limited quantity of prefilled syringes and vials that are used for clinical trials, for example. He added that health officials are already looking at regulatory pathways to use the vaccine more widely, if needed.
He said the first wave of production, if needed, could provide several hundreds of thousands of vaccine doses, and the second tranche could amount to 10 million doses. "Any pivot from that would require additional resources," Boucher said. "If we need to pull any of those levers, we're willing to do so."
Partnering with established seasonal flu vaccine producers has the benefit of a licensed platform in place that can be easily adapted to include an H5N1 vaccine virus, but he acknowledged that a downside would be a potential disruption in seasonal flu vaccine production. "There are a lot of variables that go into making that decision."
Two safety and immunogenicity studies are already under way on candidate H5N1 vaccines, Boucher told the group.
More:
The Food and Drug Administration (FDA) has found that about 1 in 5 samples of retail milk contain traces of highly contagious bird flu, though these findings may not be indicative of an infectious risk to consumers.
In an update published this week, the FDA shared some takeaways from its nationally representative commercial milk sampling study.
“The agency continues to analyze this information; however, the initial results show about 1 in 5 of the retail samples tested are quantitative polymerase chain reaction (qPCR)-positive for [Highly Pathogenic Avian Influenza] viral fragments, with a greater proportion of positive results coming from milk in areas with infected herds,” the update stated.
The FDA noted that additional testing will be required to determine if intact pathogens are actually present in the milk and if consuming these products poses a risk of infection.
“To date, the retail milk studies have shown no results that would change our assessment that the commercial milk supply is safe,” the agency shared, citing the pasteurization process that retail milk undergoes as well as the diverting and destroying of milk from infected cows.
The agency also reiterated its long-standing warning against drinking raw milk.
Earlier this year, a worker on a dairy farm was confirmed to have been infected with a highly infectious strain of bird flu in Texas. The individual worked close to cows that were found to be infected with the H5N1 strain.
According to William Schaffner, professor in the division of infectious diseases at the Vanderbilt University School of Medicine, pasteurization should kill the virus, and people generally shouldn’t be too concerned about buying milk from a grocery store.
“A bird flu virus can pick up the capacity to spread readily from person to person. This is a rare event, every 15 years or so. There’s no indication that the current bird flu virus has picked this up, but it’s out there circulating,” Schaffner told The Hill.
He emphasized that while bird flu infections are rare in the U.S., it is not a novel virus. And it is even rarer that someone infected by livestock ends up passing that virus on to another person.
Original post:
Bird flu virus traces found in 1 in 5 samples of pasteurized milk: FDA - The Hill
Dairy cattle moving between states must be tested for the bird flu virus, U.S. agriculture officials said Wednesday as they try to track and control the growing outbreak.
The federal order was announced one day after health officials said they had detected inactivated remnants of the virus, known as Type A H5N1, in samples taken from milk during processing and from store shelves. They stressed that such remnants pose no known risk to people or the milk supply.
The risk to humans remains low, said Dawn OConnell of the federal Administration for Strategic Preparedness and Response.
The new order, which goes into effect Monday, requires every lactating cow to be tested and post a negative result before moving to a new state. It will help the agency understand how the virus is spreading, said Michael Watson, an administrator with the U.S. Department of Agricultures Animal and Plant Health Inspection Service.
We believe we can do tens of thousands of tests a day, he told reporters.
Until now, testing had been done voluntarily and only in cows with symptoms.
Avian influenza was first detected in dairy cows in March and has been found in nearly three dozen herds in eight states, according to USDA.
Its an escalation of an ongoing outbreak of highly pathogenic avian influenza spread by wild birds. Since the start of the outbreak, more than 90 million birds in U.S. commercial flocks have either died from the virus or been killed to try to prevent spread.
Two people in the U.S. both farmworkers have been infected with bird flu since the outbreak began. Health officials said 23 people have been tested for bird flu to date and 44 people exposed to infected animals are being monitored.
Officials said that samples from a cow in Kansas showed that the virus could be adapting to more animals and they detected H5N1 virus in the lung tissue of a dairy cow that had been culled and sent to slaughter.
So far, officials with the Centers for Disease Control and Prevention have seen no signs that the virus is changing to be more transmissible to people.
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institutes Science and Educational Media Group. The AP is solely responsible for all content.
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Geoff Bennett:
The U.S. FDA says that samples of milk taken from grocery stores across the U.S. have tested positive for remnants of the bird flu virus that has infected dairy cows.
But the agency says it's confident the milk you are buying is safe. Officials also say the finding suggests the virus is spreading more prevalently among dairy herds than previously thought.
To help slow that spread, the USDA announced today that dairy cattle must now be tested for the virus before moving to a new state.
We're joined now by Dr. Jennifer Nuzzo, a director of the Pandemic Center at Brown University.
Thank you for being with us.
So let's start with the latest update, particles of this virus found in commercial pasteurized milk. How concerned should the everyday consumer be?
Dr. Jennifer Nuzzo, Brown University School of Public Health: I don't have any reason to be concerned at this point.
Finding evidence of genetic material, which is what the test results told us, by itself is not alarming. In order to know if the virus will infect us, we have to do a different kind of test. And this test was not that. They're actually undergoing those tests now.
But I don't have any reason to think that we will be harmed, because we use pasteurization. And I have no reason to think that the H5N1 virus is any different from all the other pathogens that we think could be in milk. Pasteurization doesn't remove the genetic material of those pathogens, but it changes the pathogens and either kills or it activates them, so that they can't infect us.
And I fully expect that that's what the test results will say, and just more reason to choose pasteurized milk over raw milk.
Original post:
Fragments of bird flu virus detected in cow's milk sold in grocery stores - PBS NewsHour
Microbiological examination of cow, milk, and cat samples early in the investigation of H5N1 avian flu in some of the first affected states found that the cats died shortly after they were fed raw colostrum from sick cows, highlighting the risk of spread from cows to other animals through contaminated milk.
A research team based at Iowa State University reported its findings on some of the earliest samples from cows and cats today in Emerging Infectious Diseases.
For the study, the scientists examined samplesmilk, serum, and tissuesfrom cows on early affected farms in Texas and Kansas. They also analyzed samples from cats that died on the farms. The initial H5N1 highly pathogenic avian influenza (HPAI) findings prompted the initial announcement from the US Department of Agriculture (USDA) on March 25.
The tissue samples in cows came from a three that were euthanized and three that died naturally. The researchers also performed postmortem exams on two adult cats from one of the farms, which had about 24 cats. The cats started showing symptoms a day after clinical disease was noted in the cows, and about half of the cats died.
Microscopic examination revealed that the H5N1 virus infects epithelial cells of mammary alveoli where milk is produced, prompting acute inflammation in the udder, which could explain the drop in milk production and high virus levels that have been turning up in milk.
The authors said the case series shows that H5N1 infection has more dramatic symptoms in cows than reflected in earlier reports of influenza A viruses in the animals.
Meanwhile, they wrote that the clinical disease in cats, especially neurologic symptoms, is consistent with earlier reports of H5N1 in cats and tracks with reports of cats eating infected wild birds and poultry products.
Though wild-bird consumption can't be ruled out in the cats from the dairy farms, known consumption of unpasteurized milk and colostrum from infected cows, a fluid that contained a high viral load, makes it a likely exposure route, the team wrote.
"Therefore, our findings suggest cross-species mammal-to-mammal transmission of HPAI H5N1 virus and raise new concerns regarding the potential for virus spread within mammal populations," they said.
Ingestion of feed contaminated with feces from wild birds is the most likely initial source of infection on dairy farms, according to the authors, who said more studies are needed to clarify transmission routes and pathogenesis within infected cattle.
Over the past few days, federal agencies involved in the nationwide H5N1 investigation and response updated their findings and provided policy clarifications.
Egg inoculation tests were negative for live infectious virus in retail milk samples that were positive for H5N1 fragments in earlier polymerase chain reaction (PCR) tests, the Food and Drug Administration (FDA) said in an April 26 update. It noted that the test results are preliminary but affirm its assessment that the commercial milk supply is safe.
The FDA also said it tested several samples of retail powered infant formula and powdered milk products marketed as toddler formula, and all were negative for H5N1 remnants on PCR testing.
Work is still under way on 297 retail samples from 38 states. The agency said that samples that are positive on PCR testing will go through egg inoculation testing.
Meanwhile, the Centers for Disease Control and Prevention (CDC) in anupdate on the same day says its ongoing susceptibility testing on commercially available antiviral drugs has found that the current H5N1 strain is susceptible to baloxavir marboxil (Xofluza).
The CDC said its earlier studies showed that the H5N1 virus from the human case in Texas was susceptible to other antivirals, including oseltamivir. However, it said one of the 200 publicly posted H5N1 samples from dairy cows found a marker with a known link to reduced susceptibility to neuraminidase inhibitors.
"The detection of this marker in one of more than 200 specimens is not surprising or concerning at this time in terms of the clinical usefulness of these drugs, but it does underscore why this kind of constant monitoring is important," the agency wrote.
Finally, the US Department of Agriculture (USDA) on April 27clarified its recent federal order barring interstate movement of lactating dairy cows without tests to ensure that the animals aren't infected with HPAI H5N1.
It said the clarification notes that the order doesn't apply to the interstate movement of dairy cows going to sale barns, which are sometimes used to consolidate and move cattle to slaughter out of state. "We are announcing this clarification over the weekend to ensure small farms have the guidance necessary to continue to move cull cattle and limit animal welfare issues," the USDA said.
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Fragments of the bird flu virus have been found in about one fifth of commercial milk samples tested in a U.S. nationally representative study, according to the Food and Drug Administration (FDA).
While the presence of traces of the virus in milk doesnt necessarily indicate a risk to consumers, more tests are needed to confirm if intact pathogen is present and remains infectious, the FDA said in a statement on itswebsite. That would determine whether there is any risk of illness associated with consuming the product, it added.
The initial study results offer a stark indication of how quickly a virus that has killed millions of birds globally is spreading among U.S. dairy cows, raising health and food security woes while spooking markets.
Read More: Is It Safe to Eat Eggs and Chicken During the Bird Flu Outbreak?
The FDA said theres a higher proportion of positive tests coming from milk in areas with infected herds. The U.S. Department of Agriculture has confirmed 33 infected herds in eight states including Texas, Kansas, Michigan, and Ohio. On Wednesday, the USDA implemented mandatory testing of dairy cows moving across state borders as part of efforts to understand the extent of the outbreak and contain the virus.
Authorities have reaffirmed that the risk to humans remain low. So far this year, the U.S. has only identified one person who has been infectedand theres been no human-to-human transmission. The person, who had direct contact with contaminated cattle, experienced only minor symptoms and was treated with Tamiflu.
To date, the retail milk studies have shown no results that would change our assessment that the commercial milk supply is safe, FDA said.
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