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.
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.
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.
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.
The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) today reported the first H5N1 avian flu virus detection in Colorado's dairy cows, raising the number of affected states to nine.
Also today, the World Health Organization (WHO), the World Organization for Animal Health (WOAH), and the UN Food and Agriculture Organization (FAO) weighed in on recent H5N1 developments in the United States and abroad. They said evolving developments with the virus, including a novel reassortant detected in three Asian countries and a spillover from wild birds to dairy cows in the United States, requires real-time monitoring.
The H5N1 detection in Colorado raises the number of herds known to be affected to 34. So far, there are no details on where the Colorado herd is located and how it may have been exposed to the virus.
Recent detections of H5N1 remnants in retail milk suggest that the virus in dairy cows may be more widespread than suggested by current animal testing.
The three global agencies raised concerns about genetic diversification of the H5N1 2.3.4.4b clade spreading in multiple world regions, as well as its ability to infect a broader range of species, with some species experiencing significant death rates, such as in sea mammals in South America.
As the virus infects more species, including a goat and dairy cows in the United States, the virus has more opportunities to generate new genotypes, which could cause different clinical pictures.
For example, the global experts said a novel H5N1 reassortant seen in poultry in Cambodia, Laos, and Vietnam over the past 2 years has now been detected in humans, one from Cambodia and the other from Vietnam. The virus contains surface proteins from an older H5N1 clade (2.3.2.1c) and internal genes from the more recent 2.3.4.4b H5N1 clade.
The WHO, WOAH, and FAO said the overall risk to humans remains low, and for people who have exposure to infected animals or their environments, the risk is low to moderate.
In other H5N1 developments:
Cows are seen on a dairy farm in Virginia on October 5, 2022. Brendan Smialowski/AFP via Getty Images hide caption
Cows are seen on a dairy farm in Virginia on October 5, 2022.
Federal officials say the risk to the public remains low after the Food and Drug Administration announced Wednesday that tests of commercially available milk detected traces of bird flu.
The announcement comes amid a national outbreak of highly pathogenic avian influenza (HPAI) among dairy cows that was first confirmed late last month. The disease, which is very contagious and often fatal in avian populations, has spread to herds in at least eight states. At least one person who was in contact with presumably sick animals also caught the virus.
But government officials and scientific experts say so far there is no evidence of infectious virus in pasteurized milk.
National Institute of Allergy and Infectious Diseases director Jeanne Marrazzo said Wednesday in a call with reporters that tests conducted on retail milk showed that there was genetic material from the virus.
Efforts to grow the virus from those samples indicated that the virus was not infectious or "alive," Marrazzo said, adding that testing was only conducted on a small set of samples.
"To date, we have seen nothing that would change our assessment that the commercial milk supply is safe," the FDA said in a statement.
Pasteurization has been used in the U.S. for decades to kill harmful bacteria and viruses in milk, but pasteurization may not erase all traces of a virus.
Some genetic material may be left behind after the pasteurization process, such as DNA or RNA, the "instructions" that tell the virus what to do, according to Cornell University food science professor Samuel Alcaine.
"A car gets in an accident. It's no longer functioning. You can't drive it. It doesn't do anything that a car does. But you sift through the rubble and you could still find the instruction manual that tells it how to work," he said.
Alcaine said that's likely what's happening with bird flu in milk: Tests show the virus used to be there, but it's no longer able to cause an infection.
The FDA said there haven't been any studies specifically on whether pasteurization inactivates bird flu in cow's milk because bovine infections are so new. However, it added that previous studies have shown that pasteurization is "very likely to effectively inactivate heat-sensitive viruses, like H5N1" and that pasteurization has inactivated bird flu in eggs, a process that occurs at a lower temperature than for milk.
The FDA said it detected bird flu in milk using quantitative polymerase chain reaction (qPCR) tests, which "do not represent actual virus that may be a risk to consumers."
Further evaluation of milk samples will be done using egg inoculation tests, the FDA said, which it called the "gold-standard for determining viable virus." The agency said it would release the results from multiple studies within days or weeks.
"There are no safety concerns," Alcaine said of milk with traces of bird flu. "I'm still buying my milk from my local grocery store."
Federal officials emphasize that any milk from infected cows is supposed to be discarded or destroyed and not enter the human food supply.
On top of that, any milk sold via interstate commerce in the U.S. is required to be pasteurized. The FDA has encouraged consumers not to drink raw, unpasteurized milk.
But Alcaine said influenza is generally not transmitted through food, and the more pressing concern is protecting people like farm workers, who could come into close physical contact with infected animals.
In an attempt to further contain the outbreak, the USDA's Animal and Plant Health Inspection Service announced an order Wednesday that requires dairy cows to test negative for bird flu before they can be moved across state lines, among other measures.
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.
News that bird flu has been spreading between cows for months and that fragments of the virus are even showing up in milk on U.S. grocery store shelves have fueled new worries about the risk the virus poses to people. Among the questions: Is the virus, known as highly pathogenic avian influenza H5N1, adapting to better infect mammals? And can people get bird flu from drinking that milk?
Science News went to the experts to find answers to those questions. The short answer is that, thanks to milk pasteurization and the way bird flu viruses spread, the risk to people remains low. Heres a deeper dive into what you should know.
Probably not in pasteurized milk.
On April 23, the U.S. Food and Drug Administration announced that fragments of the bird flus genetic material had turned up in grocery store milk. Initial results indicate that about 1 in 5 samples contain bitsof the viruss RNA,the agency announced April 25. Samples taken from areas where infected dairy cows have been found were more likely to test positive for the bird flu virus than those with no infected herds.
That doesnt mean that whole infectious viruses are present, says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota in Minneapolis.
At first blush, it would surely seem as if it should be a great concern in terms of human health. However, the good news is that while the virus is in the milk the pasteurization process actually is very effective in killing those virus particles so that in fact, we dont have to be concerned about Are we ingesting infective material?
Pasteurization raises milk to a high enough temperature to kill bacteria and viruses. Milk has always had bits of dead bacteria such as E. coli and Listeria that arent filtered out, Osterholm says. So its not surprising to find genetic remains of the flu virus, he says, but that by itself does not at all suggest a public health concern.
H5N1 is an envelope virus. And envelope viruses ones that wrap themselves in a blanket borrowed from a host cells membrane are just a little bit wimpier than non-envelope viruses and a little bit easier to inactivate, says Meghan Davis, an environmental epidemiologist at the Johns Hopkins Bloomberg School of Public Health. That means that theres some reassurance that pasteurization ought to be working.
Because H5N1 has only recently been found in cattle, no studies have directly tested milk pasteurizations ability to kill the virus, the FDA said in a statement April 23. But studies have shown that egg pasteurization, which is done at lower temperatures than milk pasteurization, inactivates the virus.
For those reasons, government officials stress that pasteurized milk is safe to drink. But the FDA recommends that people dont drink raw milk, which has not been pasteurized.
Davis says there are many reasons to avoid raw milk and products made from it. We know that raw milk [can contain] other infectious diseases and there have been outbreaks linked to raw milk consumption. So categorically I dont recommend it.
Some goats have also been infected with H5N1, so Davis suggests avoiding raw goat and sheep milk products, too.
Decades of evidence suggest thats not likely, Osterholm says.We have no evidence that humans have become infected from influenza A virus via ingestion.
Some scavenger mammals have become infected with H5N1 from eating dead birds. But to get into cells, influenza viruses need to grab onto receptors, cell surface proteins studded with certain sugars. In humans, those sugars are different than the versions in scavengers. People carry the entry portals in their upper respiratory tract and the eyes. The one person in the United States who recently caught bird flu worked with cows at a farm in Texas and was diagnosed with conjunctivitis, an eye infection.
It might even be difficult for people to catch the bird flu from infected cows, Osterholm says. If you look at the experience weve had in the past, even with all of the human contact that occurred with infected flocks [of] turkeys and chickens over the course of the past several years, weve just seen an absence of infection in humans. Both the U.S. Centers for Disease Control and Prevention and World Health Organization have designated the virus as low risk for humans.
The U.S. Department of Agriculture first announced finding a strain of bird flu in dairy cattle in Kansas and Texas on March 25 (SN: 4/3/24). Since then, the virus has been found in dairy cows in eight states. The same version of the virus infecting cows called clade 2.3.4.4b has also been found in poultry in five states, the USDA said in a federal order. That order announced mandatory testing for all dairy cows before they can be moved to another state, and also requires tracing the previous movements of cows from infected herds. The order will go into effect on April 29.
H5N1 may have jumped into cattle only once and then spread from cow-to-cow, evolutionary biologist Michael Worobey of the University of Arizona in Tucson posted on X (formerly Twitter) after he and colleagues analyzed 239 bird flu viruses from cattle and other species. The jump may have happened in late December 2023, months earlier than thought.
These findings are still preliminary and havent been independently verified by other scientists, Davis cautions. But they do suggest that bird flu in cattle is probably more widespread than what weve identified based on the reported cases on the USDA dashboard. What were looking at is probably circulation, potentially cow-to-cow, but we dont yet know the extent.
At the moment we have both concern and reassurance, she says. Despite the low risk, we have the concern that this particular H5N1 has had staying power and has been around globally since 2020. It has been in the U.S. since 2022. The virus continues to cause major outbreaks in birds and has jumped into many species of mammals. That pattern is different from what was seen with earlier iterations of H5N1 avian influenza. It would flash up, wed have cases and then it would die off by the next year. But thats not what were seeing here.
Yes, but cases tend to be fairly mild. H5N1 infections in cows can cause a drop in appetite and milk production, abnormal feces, tiredness, fever and other symptoms.
Davis, a former dairy veterinarian, says that vets often get calls that cows are off feed, meaning the animals arent eating well or giving as much milk as usual. Those symptoms are not specific to any particular disease, so cases of H5N1 influenza may easily have been overlooked.
Some cows may not have any symptoms. Lung tissue taken from one cow with no symptoms tested positive for the virus, the USDA announced April 24.
The virus has also been found in cats on dairy farms in Texas and in Poland, South Korea and France. At least one cat died, according to the World Organization for Animal Health.
For poultry such as chickens and turkeys, the virus can be deadly, destroying flocks in a matter of days.
Possibly, Osterholm says. In our business, we almost sleep with one eye open, just because on any one given day there could be a change in the virus from mutation or reassortment.
Reassortment happens when flu strains swap part of their genetic instructions. Reassortment generated the H1N1 flu strain that caused a pandemic in 2009. In a pig, bits from the 1918 pandemic flu strain combined with pieces from a virus that was already a mish-mash of a swine flu virus and an avian flu virus. The resulting virus eventually infected people (SN: 5/22/09; SN: 2/12/10). The current H5N1 resulted from the reassortment of avian influenza viruses from poultry and wild birds.
What we are concerned about is adaptation of the virus to better suit some of the receptors that humans might have, which is why any transmission out of bird populations into any mammal is initial cause for concern, Davis says. People working on dairy farms, those in the dairy production chain and anyone else who may come into contact with raw milk, cows or poultry should wear protective equipment to avoid possible infection. She also advocates for testing farm workers, their families and others in their communities.
Both Davis and Osterholm are concerned about the virus infecting other food animals.
The challenge that I see right now on U.S. farms is a virus getting into hogs, Osterholm says. Pigs carry receptors similar to the ones found in both humans and birds, making swine a hog-heaven for bird flus that have potential to become a pandemic. Meanwhile, Davis says, if this virus can infect both cows and goats, sheep are on my suspicion list for another potential species of concern.
H5N1 avian influenza viruses have been found in birds since 1996 and have infected more than 880 people globally since 1997. In the United States, a poultry worker tested positive for H5N1 in 2022. The dairy farmworker with conjunctivitis was only the second person in the United States with a documented bird flu infection.
So far, H5N1 has not developed the ability to spread easily from person-to-person, which would make it a pandemic-potential virus. Lightning could strike tomorrow, Osterholm says, but at least based on the track record so far, theres been very little evidence to support that this is going to infect humans [and] then be transmitted by people to other people.
The discovery of fragments of avian flu virus in milk sold in U.S. stores, including in about 20% of samples in initial testing across the country, suggests that the H5N1 virus may be more widespread in dairy cattle than previously realized.
The Food and Drug Administration, which announced the early results from its nationally representative sampling on April 25, 2024, was quick to stress that it believes the commercial milk supply is safe. The FDA said initial tests did not detect any live, infectious virus. However, highly pathogenic avian influenza virus can make cows sick, and the flu viruss presence in herds in several states and new federal restrictions on the movement of dairy cows between states are putting economic pressure on farmers.
Five experts in infectious diseases in cattle from the University of California, Davis Noelia Silva del Rio, Terry Lehenbauer, Richard Pereira, Robert Moeller and Todd Cornish explain what the test results mean, how bird flu can spread to cattle and the impact on the industry.
Its crucial to understand that the presence of viral fragments of H5N1 doesnt indicate the presence of intact virus particles that could cause disease.
The commercial milk supply maintains safety through two critical measures:
First, milk sourced from sick animals is promptly diverted or disposed of, ensuring it does not enter the food chain.
Second, all milk at grocery stores is heat treated to reduce pathogen load to safe levels, mainly by pasteurization. Pasteurization has been shown to effectively inactivate H5N1 in eggs, and that process occurs at a lower temperature than is used for milk.
The viral fragments were detected using quantitative polymerase chain reaction testing, which is known for its exceptional sensitivity in detecting even trace amounts of viral genetic material. These fragments are only evidence that the virus was present in the milk. They arent evidence that the virus is biologically active.
To evaluate whether the presence of the viral fragments corresponds to a virus with the capacity to replicate and cause disease, a different testing approach is necessary. Tests such as embryonated egg viability studies allow scientists to assess the viruss ability to replicate by injecting a sample into an embryonated chicken egg. That type of testing is underway.
On April 24, 2024, the FDA said it had found no reason to change its assessment that the U.S. milk supply is safe. The agency does strongly advise against consuming raw milk and products derived from it because of its inherent risks of contamination with harmful pathogens, including avian flu viruses.
Currently, cows confirmed to have H5N1 have different symptoms than the typical flu-like symptoms observed in birds.
Abnormal milk and mastitis, an inflammatory response to infection, are common. While there is speculation that other bodily secretions, such as saliva, respiratory fluids, urine or feces, may also harbor the virus, that has yet to be confirmed.
How waterfowl or other birds transmitted H5N1 to cattle is still under investigation. In 2015, an outbreak of highly pathogenic avian influenza in commercial poultry farms reached its peak in April and May, the same time birds migrated north. Birds can shed the virus through their oral, nasal, urine and fecal secretions. So the virus could potentially be transmitted through direct contact, ingesting contaminated feed or water, or inhaling the virus.
Infected dairy cows can shed the virus in milk, and they likely can transmit it to other cows, but that still needs to be proven.
Contagious pathogens that cause mastitis can be transmitted through milking equipment or contaminated milkers gloves. Ongoing research will help determine whether this is also a potential transmission route for H5N1, and if so, what makes the virus thrive on mammary tissue.
For the dairy industry, infection of cattle with H5N1 avian influenza virus creates challenges at two levels.
The overriding concern is always for the safety and healthfulness of milk and dairy products.
Existing state and federal regulations and industry practices require sick cows or cows with abnormal milk to be segregated so that their milk does not enter the food supply. Proper pasteurization should kill the virus so that it cannot cause infection.
The American Association of Bovine Practitioners has also developed biosecurity guidelines for H5N1, focusing on key practices. These include minimizing wild birds contact with cattle and their environment, managing the movement of cattle between farms, isolating affected animals, avoiding feeding unpasteurized (raw) colostrum or milk to calves and other mammals, and ensuring the use of protective personal equipment for animal caretakers.
The other major concern is for the health of the dairy herd and the people who take care of the dairy cattle. A farm worker who handled dairy cows contracted H5N1 in Texas in March 2024, but such cases are rare.
No vaccines or specific therapies are available for avian influenza infections in dairy cattle. But following good sanitation and biosecurity practices for both people and cows will help to reduce risk of exposure and spread of the avian influenza virus among dairy cattle.
For cows that get the virus, providing supportive care, including fluids and fever reducers as needed, can help them get through the illness, which can also cause loss of appetite and affect their milk production.
Dairy farms facing an outbreak will have economic losses from caring for sick animals and the temporary reduction in milk sales. Approximately 5% to 20% of the animals in the affected herds have become ill, according to early estimates. Affected animals typically recover within 10 to 20 days.
At least 22 states have restricted importing dairy cattle to prevent the viruss spread, and the federal government announced it will require that lactating dairy cattle be tested before they can be moved between states starting April 29, 2024. While the overall impact on U.S. milk production is projected to be minor on an annual basis, it could lead to short-lived supply disruptions.
The federal governments monitoring and food safety measures, along with pasteurization, provide important safeguards to protect the public from potential exposure to avian influenza virus through the food chain.
Drinking raw milk, however, does represent a risk for exposure to multiple diseases, including H5N1. This is why the FDA and Centers for Disease Control and Prevention strongly recommend drinking only pasteurized milk and dairy products.
This article, published April 25, 2024, has been updated with new FDA test results.
The USDA and FDA said the commercial milk supply remains safe for now.
via
April 24, 2024, 9:41 AM ET
4 min read
As federal agencies and state partners continue investigating outbreaks of highly pathogenic avian influenza (HPAI) -- more commonly referred to as bird flu -- the U.S. Food and Drug Administration says it discovered fragments of the virus in some samples of milk.
In an update from the FDA, the agency said it tested milk samples by polymerase chain reaction (PCR) and found the presence of fragments of the virus, which is not the same as infectious virus and currently poses no increased risk to human health.
"Based on available information, pasteurization is likely to inactivate the virus, however the process is not expected to remove the presence of viral particles," the FDA said.
"At this point, when you look for something in public health, science and medicine, your chances of finding it go up," ABC News chief medical correspondent Dr. Jennifer Ashton said.
Citing a senior official at the Centers for Disease Control and Prevention, Ashton said, "the overall risk to the general American population is low, particularly from dairy cows, however, 'they are taking this very seriously.'"
Importantly, the FDA stated, "we have seen nothing that would change our assessment that the commercial milk supply is safe" and expect new results from multiple studies "in the next few days to weeks."
Concerns were first raised last month when HPAI was detected in dairy cows across multiple states, but the USDA and FDA maintain that the U.S. commercial milk supply remains safe due to "the pasteurization process and the diversion or destruction of milk from sick cows."
"Nearly all (99%) of the commercial milk supply that is produced on dairy farms in the U.S. comes from farms that participate in the Grade 'A' milk program and follow the Pasteurized Milk Ordinance (PMO), which includes controls that help ensure the safety of dairy products," the FDA update continued.
Aside from pasteurized milk, both the FDA and CDC warn against drinking raw milk or products made with it that are typically bought at farms or local stores, due to possible viruses or bacteria that can lead to infection or foodborne illness.
Twenty states explicitly prohibit raw milk sales in some form. And milk that travels across state lines must be pasteurized, according to federal regulations.
HPAI was first detected in 1996 and there have only been two cases of human H5N1 in the U.S. so far. There have been no reports of human-to-human spread in the U.S.
