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Heres the latest news about a global outbreak of H5N1 bird flu that started in 2020, and recently spread among cattle in U.S. states and marine mammals across the world, which has health officials closely monitoring it and experts concerned the virus could mutate and eventually spread to humans, where it has proven rare but deadly.
A sign warns of a outbreak of bird flu.
May 15The Centers for Disease Control and Prevention released influenza A waste water data for the weeks ending in April 27 and May 4, and found several states like Alaska, California, Florida, Illinois and Kansas had unusually high levels, though the agency isnt sure if the virus came from humans or animals, and isnt able to differentiate between influenza A subtypes, meaning the H5N1 virus or other subtypes may have been detected.
May 10The Food and Drug Administration announced it will commit an additional $8 million to ensure the commercial milk supply is safe, while the Department of Agriculture said it will pay up to $28,000 per farm to help mitigate the spread of the disease, totaling around $98 million in funds.
May 9Some 70 people in Colorado are being monitored for bird flu due to potential exposure, and will be tested for the virus if they show any symptoms, the Colorado Department of Public Health told Forbesit was not immediately clear how or when the people were potentially exposed.
May 1The Department of Agriculture said it tested 30 grocery store ground beef products for bird flu and they all came back negative, reaffirming the meat supply is safe.
May 1The Food and Drug Administration confirmed dairy products are still safe to consume, announcing it tested grocery store samples of products like infant formula, toddler milk, sour cream and cottage cheese, and no live traces of the bird flu virus were found, although some dead remnants were found in some of the foodthough none in the baby products.
April 30Wenqing Zhang, head of the World Health Organization's Global Influenza Programme, said during a news briefing "there is a risk for cows in other countries to be getting infected," with the bird flu virus, since its commonly spread through the movement of migratory birds.
April 29The Department of Agriculture told Forbes it will begin testing ground beef samples from grocery stores in states with cow outbreaks, and test ground beef cooked at different temperatures and infected with the virus to determine if it's safe to eat.
April 24The USDA said cow-to-cow transmission may be occurring due to the cows coming into contact with raw milkand warned against humans and other animals, including pets, consuming unpasteurized milk to prevent potential infection.
April 18Jeremy Farrar, chief scientist for the World Health Organization, said during a press conference the threat of bird flu spreading between humans was a great concern, since its evolved and has increasingly been infecting mammals (on land and sea), which means it could possibly spread to humans.
April 1The CDC reported the second U.S. human case of bird flu in a Texas dairy farmer who became infected after contracting the virus from infected dairy cows, but said the person was already recovering.
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Bird flu doesnt transmit easily from person-to-person, according to the World Health Organization. Bird flu rarely affects humans, and most previous cases came from close contact with infected poultry, according to the CDC. Because human-to-human spread of bird flu poses pandemic potential, each human case is investigated to rule out this type of infection. Though none have been confirmed, there are a few global casesnone in the U.S.where human-to-human transmission of bird flu was thought to be probable, including in China, Thailand, Indonesia and Pakistan.
It is very deadly. Between January 2003 and March 28, 2024 there have been 888 human cases of bird flu infection in humans, according to a report by the World Health Organization. Of those 888 cases, 463 (52%) died. To date, only two people in the U.S. have contracted H5N1 bird flu, and they both were infected after coming into contact with sick animals. The most recent case was a dairy worker in Texas who became ill in March after interacting with sick dairy cows, though he only experienced pink eye. The first incident happened in 2022 when a person in Colorado contracted the disease from infected poultry, and fully recovered.
Raw, unpasteurized milk is unsafe to drink, but pasteurized milk is fine, according to the FDA. Bird flu has been detected in both unpasteurized and pasteurized milk, but the FDA recommends manufacturers against making and selling unpasteurized milk since theres a possibility consuming it may cause bird flu infection. However, the virus remnants in pasteurized milk have been deactivated by the heat during the pasteurization process, so this type of milk is still believed safe to consume.
The CDC warns against eating raw meat or eggs infected with bird flu because of the possibility of transmission. However, no human has ever been infected with bird flu from eating properly prepared and cooked meat, according to the agency. The possibility of infected meat entering the food supply is extremely low due to rigorous inspection, so properly handled and cooked meat is safe to eat, according to the USDA. To know when meat is properly cooked, whole beef cuts must be cooked to an internal temperature of 145 degrees Fahrenheit, ground meat must be 160 degrees and poultry must be cooked to 165 degrees. Rare and medium rare steaks fall below this temperature. Properly cooked eggs with an internal temperature of 165 degrees fahrenheit kills bacteria and viruses including bird flu, according to the CDC. It doesnt matter if they may or may not have [avian] influenza runny eggs and rare pieces of meat are never recommended, Francisco Diez-Gonzalez, director and professor for the Center for Food Safety at the University of Georgia, told Forbes. To play it safe, consumers should only eat fully cooked eggs and make sure the yolks are firm with no runny parts, Daisy May, veterinary surgeon with U.K.-based company Medivet, said.
Symptoms of bird flu include a fever, cough, headache, chills, shortness of breath or difficulty breathing, runny nose, congestion, sore throat, nausea or vomiting, diarrhea, pink eye, muscle aches and headache. However, the CDC advises it cant be diagnosed based on symptoms alone, and laboratory testing is needed. This typically includes swabbing the nose or throat (the upper respiratory tract), or the lower respiratory tract for critically ill patients.
This years egg prices have increased as production decreased due to bird flu outbreaks among poultry, according to the USDA. A dozen large, grade A eggs in the U.S. costed around $2.99 in March, up almost a dollar from the fall. However, this price is down from a record $4.82 in January 2023, which was also spiked by bird flu outbreaks. Earlier this month, Cal-Maine Foodsthe countrys largest egg producertemporarily halted egg production after over one million egg-laying hens and chickens were killed after being infected with bird flu.
Once chickens have been infected with bird flu, farmers quickly kill them to help control the spread of the virus, since bird flu is highly contagious and fatal in poultry. The USDA pays farmers for all birds and eggs that have to be killed because of bird flu, as an incentive to responsibly try and curb the spread of the disease. The USDA has spent over $1 billion in bird flu compensation for farmers since 2022, according to the nonprofit Food & Environment Reporting Network.
The FDA has approved a few bird flu vaccines for humans. The U.S. has a stockpile of vaccines for H5N1 bird flu, but it wouldnt be enough to vaccinate all Americans if an outbreak were to happen among humans. If a human outbreak does occur, the government plans to mass produce vaccines, which can take at least six months to make enough for the entire population. Sequirs, the maker of one of the approved vaccines, expects to have 150 million vaccines ready within six months of an announcement of a human bird flu pandemic. Although there are approved vaccines for other variants designed for birds, there are none for the H5N1 variant circulating. However, the USDA began trials on H5N1 animal-specific vaccines in 2023.
As of May 14, more than 90 million poultry (primarily chickens) in 48 states have been euthanized because of bird flu since 2022, and 46 dairy cow herds across nine states have tested positive, according to data from the CDC (unlike chickens, cows appear to recover from the virus). The USDA believes wild migratory birds are the original source of the cow outbreaks that recently has experts concerned it may mutate and spread more easily in humans, though the CDC said its risk to the public remains low. Farrar called the cattle infections in the U.S. a huge concern, urging public health officials to continue closely monitoring the situation because it may evolve into transmitting in different ways. The increased number of mammal bird flu infections since 2022 could indicate that the virus is looking for new hosts, and of course, moving closer to people, Andrea Garcia, vice president of science, medicine and public health for the American Medical Association, said. More than 10 human bird flu cases were reported to the World Health Organization in 2023, and all but one survived. Bird flu has devastated bird populations, and 67 countries reported the deaths of 131 million poultry in 2022 alone. Although bird flu typically infects wild birds and poultry, its spread to other animals during the outbreak, and at least 10 countries have reported outbreaks in mammals since 2022. Around 17,400 elephant seal pups died from bird flu in Argentina in 2023, and at least 24,000 sea lions died in South America the same year. Besides cattle, bird flu has been detected in over 200 other mammalslike seals, raccoons and bearsin the U.S. since 2022. Although rare, even domestic pets like dogs and cats are susceptible to the virus, and the FDA warns against giving unpasteurized milk to cats to avoid possible transmission.
WHO Warns Threat Of Bird Flu Spreading To Humans Is Great Concern (Forbes)
One In Five Milk Samples From Across US Had Traces Of Bird Flu Virus, FDA Says (Forbes)
Can Pets Get Bird Flu? Heres What To Know (Forbes)
Avian H5N1 (Bird) Flu: Why Experts Are WorriedAnd What You Should Know (Forbes)
It was in 1997 while working at WILL-AM 580 in Urbana that I first heard about Asian highly pathogenic avian influenza (HPAI), i.e. bird flu. A strain of the flu, H5N1, especially deadly for poultry, had somehow infected humans that year during an outbreak in Hong Kong.
I remember asking science folk a lot smarter than me whether the virus could spread from human to human. I was reassured that the chances were miniscule.
Since then, bird flu has spread among poultry and wild birds to more than 50 countries, and the H5N1 virus has reached epidemic proportions for poultry in Bangladesh, China, Egypt, India, Indonesia, and Vietnam.
Still, the spread of HPAI and its bird flu variations to humans remains low, even as cases have ticked up in the last few years. The Centers for Disease Control and Prevention report that:
HPAI A (H5N1) virus infections have been reported in more than 890 people with approximately 50% case fatality proportion since 1997, including 20 cases and seven deaths in Hong Kong during 1997-2003, and more than 870 cases reported in 22 countries since November 2003.
Worrisome for sure. Even as the chances for human to human infection remains very rare, but not impossible.
But since December 2019, we live in a decidedly different world. Thats when Wuhan, China became the epicenter for SARS-CoV-2, the virus that causes COVID-19. Just how SARS was unleashed on the planet still isnt exactly clear. The U.S. office of the director of National Intelligence and National Intelligence Council reports:
All agencies assess that two hypotheses are plausible: natural exposure to an infected animal and a laboratory-associated incident.
Only China knows for sure and they have been less than transparent. Regardless, it was possible that the COVID pandemic was the result of natural exposure plus SARS ability to mutate rapidly.
What was clear is U.S. preparation and initial response to COVID was woefully inadequate. And at the top of the list was downplaying the infection, giving the budding pandemic a foothold on U.S. soil.
Which takes us to the shocking USDA announcement on March 25 that avian influenza has been detected for the first time ever in dairy cattle. A month later, on April 23, the Food and Drug Administration reported that genetic material from H5N1 bird flu is in the commercial milk supply.
As of May 6, USDA had identified infected herds in nine states Texas, Kansas, New Mexico, Michigan, Idaho, Colorado, North Carolina, Ohio, and South Dakota.
No one knows with certainty how big is the true outbreak nor how, where and when H5N1 is mutating. It is reasonable and logical to think the avian flu cattle outbreak is larger than reported.
On April 5, CDC reported the first cow-to-human infection of H5N1 in a person in Texas working with dairy cows.
Its fair to say that the outbreak is evolving, making it crucial that federal, state and local actors play nice in the sandbox together for the good of the public.
Thus far, that has not been the case.
The CDC, state agencies and the dairy industry cant get on the same page on whats necessary to control and contain the current avian flu outbreak among dairy cows.
High ranking CDC officials suggest it might be necessary sooner rather than later to send federal teams to farms to check on the health of dairy workers and collect data that might be helpful to limit the spread.
State agriculture officials have voiced opposition saying farmers dont want any part of federal officials on their property. Texas Agriculture Commissioner Sid Miller, who is speculated to be a possible pick for USDA secretary should Donald Trump win the presidency in November, was blunt: Its overreach. They dont need to do that. They need to back off.
CDC finds itself in the position of sweet talking, coddling and looking for middle ground as it races to determine how the outbreak is spreading among dairy cattle, and to what degree is the human population at risk. Thats less than ideal. Lack of transparency. Lack of data collection. Lack of communication.
USDAs Animal and Plant Health Inspection Service issued a federal order on April 24 requiring mandatory testing for interstate movement of dairy cattle and mandatory reporting of positive influenza A nucleic acid detection. Thats helpful.
It is possible that H5N1 avian flu has been brewing in the U.S. cattle herd since at least last December right under the noses of the feds.
Which is a little scary if one considers the possibility that avian flu may one day somehow infect pigs.
It turns out that bird flu in the pig population would be an epidemiologists worst nightmare, because pigs have both human and avian flu receptors, which could allow the virus to figure out how to adapt easily to human hosts.
Its time for all the avian flu actors to realize theyre playing with fire and learn to work together. Anything less repeats the mistakes learned in the COVID pandemic.
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Oregon Health Authority (OHA) is reminding people of the risks associated with raw (unpasteurized) milk consumption amid the current H5N1 bird flu outbreak in dairy cattle.
The U.S. Food and Drug Administration (FDA) recently tested 297 retail milk samples from 38 states for H5N1 virus. About 20% of these samples tested positive for H5N1 viral fragments, but none contained live infectious virus because the H5N1 virus had been killed through pasteurization.
According to the U.S. Department of Agriculture (USDA), there are 49 dairy cattle H5N1 outbreaks across nine states. No outbreaks have occurred in Oregon, but H5N1 is believed to be more widespread than current testing suggests.
We know that if H5N1 is present in the milk of infected dairy cattle, it will be killed by pasteurization, said Dean Sidelinger, M.D., M.S.Ed., health officer and state epidemiologist at OHA. Drinking raw milk carries many health risks, and those risks may now include H5N1 infection.
Pasteurized milk is extremely safe and has undergone a heating process that kills disease-causing bacteria and viruses. According to the Centers for Disease Control and Prevention (CDC), people who consume unpasteurized milk are at risk for a variety of illnesses such as E. coli and Salmonella. Only pasteurized milk is sold in stores and provided to children in school lunches.
Raw milk that someone consumes from the same farm over a duration of time may not always be safe. Raw milk can get contaminated in many ways. While good safety practices can reduce the chance of germs getting in raw milk, they cannot eliminate all risk.
Source: Oregon Health Authority
The H5N1 bird flu, highly infectious and deadly in birds, has been around for nearly three decades, but recently, it has been changing in ways that raise alarms for many scientists and public health officials.
In particular, the recent spread of the virus among dairy cows and the discovery of genetic traces of the virus in 1 in 5 milk samples have sparked concerns that the virus may become more transmissible to humans. (No live virus strains of were found in the milk samples, and the Food and Drug Administration says pasteurized dairy products are safe to consume -- although raw milk and unpasteurized cheeses should be avoided.)
While the public may be weary of pandemic news following four years of COVID-19, now is a critical time for scientists, public health officials and the general public to take preventive action, said Michele Barry, MD, director of the Stanford Center for Innovation in Global Health and senior associate dean of global health.
This includes taking steps to protect and monitor the health of livestock and the people who care for them through a "One Health approach" -- meaning one that fosters collaboration between countries, disciplines, and sectors to prevent disease outbreaks among humans and animals and protect their shared environments.
"This virus has the potential to seriously disrupt our agricultural supplies and also jump from other mammals to humans and become an epidemic or even a pandemic," Barry said.
This virus has the potential to seriously disrupt our agricultural supplies and also jump from other mammals to humans and become an epidemic or even a pandemic.
Barry has responded to global pandemic threats ranging from the 2014 Ebola epidemic in West Africa to COVID-19, developed recommendations for how the CDC can strengthen its Global Migration and Quarantine division to prevent future pandemics, and advises on pandemic prevention as an elected member of the Global Health Advisory Board for the Council on Foreign Relations.
She discussed the response to H5N1, also known as highly pathogenic avian influenza A, and why recent developments should serve as a wake-up call to heighten surveillance by state and federal health officials, increase collaboration between farms and health officials, and improve international collaboration on pandemic prevention. This Q&A has been edited for length and clarity.
What do we know so far about the virus's impact on humans, and what should we be watching for?
We're aware of only one suspected transmission from a mammal to a human -- in a dairy worker this April. The case was mild and presented mainly as conjunctivitis. But birds can also transmit the virus to humans; since 1996, 868 cases have been recorded in humans --of which more than half have been fatal. Most of the sick were infected on the job. While there's still much we don't know about the mortality rate in humans, these numbers are very concerning.
We have no current evidence of human-to-human transmission, but we also lack data. In the recent case of the infected dairy worker, researchers were unable to follow up or do serologic testing to understand how transmissible the virus might be to humans. The CDC must be invited in by states to conduct surveillance, andsome agricultural officials and dairy farms haveconcerns about public health investigators gaining access to farms. To incentivize testing and surveillance, the federal government has offered up to $28,000 to livestock farms.
We need to closely monitor dairy and poultry farms, keeping an eye out for upticks in occupational illnesses and deaths, and ideally conducting blood tests among the animals and workers that can help us detect the virus in a population even if it is spreading asymptomatically.
We also need to closely monitor pig farms, because if this virus jumps to pigs, it could more easily mutate into an effective human-to-human transmitter.
We also need to closely monitor pig farms, because if this virus jumps to pigs, it could more easily mutate into an effective human-to-human transmitter. Pigs are known as mixing vessels for influenza viruses because they can be infected by avian, swine and human influenza viruses. The genetic diversity of influenza viruses in pigs provides opportunities for the viruses to intermix genes and adapt to new hosts, including humans.
Are we any better prepared for bird flu than we were for COVID-19, should it become more transmissible in people?
In terms of treatments and vaccines, we are in a better position than we were at the beginning of COVID-19. Tamiflu, an antiviral medicine for treating the flu, appears to retain its effectiveness against this flu strain, and the U.S. has some stockpile of this medicine. We don't yet have a vaccine for this specific flu strain, but we do have vaccine candidates and a platform with which to build it.
However, it takes time to develop and scale up a vaccine. In a recent presentation to the Council on Foreign Relations, the CDC's deputy director, Nirav Shah, MD, acknowledged that there's a trade-off when it comes to developing an H5N1 vaccine. Doing so could pull resources from the development of the seasonal flu vaccine. In a regular year, the seasonal flu can hospitalize hundreds of thousands of people and kill tens of thousands -- so maintaining seasonal flu vaccination programs is critical.
Describe some key lessons learned in pandemic preparedness and prevention that you've helped surface through your work with the Council on Foreign Relations and the CDC. Are we heeding these lessons now?
We have learned many lessons in pandemic prevention from COVID-19, but I think many of them have been ignored. In terms of surveillance, communication, coordination and cooperation, we're not where we need to be.
We still have not changed our public health response by centralizing it. That's hindering the CDC's ability to go into states and conduct necessary surveillance on farms without being asked to come in.
A key lesson learned from COVID-19 was the importance of a centralized response. In the U.S., we still have not changed our public health response by centralizing it. That's hindering the CDC's ability to go into states and conduct necessary surveillance on farms without being asked to come in.
It's very encouraging that the U.S. government has now committed to providing funding to livestock farms to support their preventive measures and testing for the virus, along with funding to support states that are restricting the movement of affected cattle. This may not be enough to really get our arms around this problem, but it's a promising start.
Another key lesson was the need for a surge fund to ensure that stocks of vaccine, personal protective equipment and medications can be scaled up quickly. These recommendations have not been implemented, nor has the U.S. increased sufficient funding to the CDC to deal with multiple pandemic threats at once.
Internationally, nations have yet to sign a pandemic accord meant to address the shortfalls in pandemic response that surfaced during COVID-19.
We need to educate farmworkers about the risks of exposure to the virus and how they can protect themselves.
What can be done to minimize human exposure and improve surveillance among farmworkers, especially given that this population is often marginalized, faces language barriers and may not trust the government?
Perhaps most importantly, we need to educate farmworkers about the risks of exposure to the virus and how they can protect themselves. The federal government and local public health departments need to offer personal protective equipment such as N95 masks and gloves for farmworkers and teach them how to use it. We could also consider even more substantial financial incentives for dairy farms to participate in surveillance as well as ensure protection for undocumented workers involved in dairy farm work.
We can also protect farmworkers by mitigating the virus's spread in livestock. For instance, a vaccine exists for H5N1 in poultry and has been used, but it's not universal.
If we do face outbreaks on farms, Tamiflu, an antiviral, could be used prophylactically in settings with epidemic spread to help until a vaccine is developed. Of course, we always worry about antiviral resistance developing if Tamiflu is used indiscriminately.
While the current focus is on livestock, H5N1 has already caused widespread deaths in wild bird populations, infected at least 48 mammalian species and been described as "an ecological disaster." What can this impact on wild species tell us?
H5N1 has killed tens of thousands of marine mammals, including 24,000 sea lions in South America, and it threatens many other species. Yet such animal die-offs are often buried in the news -- to our detriment.
In West Africa, mass die-offs of gorillas and other mammals have been important harbingers of Ebola outbreaks in humans. H5N1 is a reminder of the very intimate connection between the health of wild animals, livestock and humans. Supporting healthy ecosystems is critical to preventing the next pandemic.
Image: Emily Moskal
On May 7, health influencer Paul Saladino, M.D.. posted a video to his X account that promoted feeding "raw dairy" to infants. The post received over 90,000 views and sparked strong backlash before it was removed the following day. Saladino regularly advocates for "animal-based" diets featuring raw milk, including on his TikTok channel where he has over half a million followers.
Interest in raw milk is rising in the U.S., fueled by both "wellness" and conservative influencers on social media. Posts promoting unpasteurized dairy have racked up millions of views, and celebrities including Gwyneth Paltrow have touted the supposed benefits.
But health officials have long warned against consuming raw dairy because it can harbor germs that pose serious health risks. The American Academy of Pediatrics warns that infants, children and pregnant women are at higher risk of illness from dairy products that haven't been pasteurized a process that uses heat to kill off dangerous organisms.
click to expand
"Do not consume unpasteurized dairy products," Dr. Nidhi Kumar recentlytold CBS New York. "I know there are people that are real advocates for it, but this is not the time to do it."
The Food and Drug Administration and the Centers for Disease Control and Prevention have stepped up their warnings after outbreaks of H5N1, or bird flu, started spreading through dairy farms in multiple U.S. states this spring.
High concentrations of the virus have been found in raw milk from infected herds, and officials have cautioned people to avoid milk that hasn't been commercially processed. Testing confirms pasteurization kills the virus, and the FDA says the commercial milk supply is safe.
Americans consumed raw milk until the late 19th century, when pasteurization became common practice. Back then, it caused hundreds of outbreaks of tuberculosis and bacterial infections, researchers say. Numerous states began mandating pasteurization and the U.S. federal government eventually banned interstate sales of unpasteurized milk in the late 1980s. Some states outlaw its sale.
Still, the product maintained its popularity with a relatively small number of Americans. Around 4.4% of Americans reported consuming raw milk in the most recent FDA research, which combined surveys from 2016 and 2019.
But in recent years, raw milk has seen a bit of a resurgence. Lawmakers in six states have legalized its sale since 2020, pushing the total number of states in which selling raw milk is legal to more than 30, though some only allow it to be sold on farms. Americans can buy unpasteurized milk in conservative and liberal states at markets in Georgia and high-end grocery stores like Erewhon in California. Google Trends data shows a steady uptick in searches for the product.
And sales of raw milk appear to be on the rise,The Associated Pressreports, citing data from market research firm NielsenIQ. Since the bird flu virus was confirmed in U.S. cattle in March, weekly sales of raw cow's milk have ticked up 21% to 65% compared with the same periods a year ago, according to NielsenIQ, whose figures include grocery stores and other retail outlets. Even so, it remains a very small fraction of overall milk sales.
The growing legalization of unpasteurized dairy has coincided with a decline in confidence in public health advice from the CDC since the coronavirus pandemic, which has been noted in research and polls. The trend has also aligned with an overall growth in the organic food industry.
At the same time, influencers on social media have claimed raw milk has health benefits that are lost in the pasteurization process something scientists and public health officialsstrongly dispute. Saladino, who posted the video advocating raw milk for infants, did not respond to a CBS News request for comment as to why his post was removed. Several other videos on his account promote the consumption of raw milk, including one showing an infant drinking raw milk from a bucket.
TikTok videos promoting raw milk received millions of views in the last year, prompting some doctors and prominent content creators like Hank Greeneto create videos to counter the misinformation they saw spreading about the product.
On Facebook, data from the social monitoring platform CrowdTangle shows that the most popular posts on "raw milk" over the last year referred favorably to the product. And on Truth Social a platform founded by former President Donald Trump users have made light of recent reports about animals dying after drinking raw dairy from infected cows, in posts with thousands of likes.
The FDA and CDC strongly advise against the consumption of or sale of raw milk or raw milk products, warning that it "can carry dangerous bacteria such as Salmonella, E. coli, Listeria, Campylobacter, and others that cause foodborne illness."
"Raw milk can be contaminated with harmful germs that can make you very sick," the CDC says.
The FDA has also debunked what it calls "milk myths," including the false claim that pasteurization kills the nutritional value of milk or that it causes lactose intolerance or allergic reactions.
Officials have renewed warnings to consumers in recent weeks. An outbreak of bird flu in dairy cows was first reported in late March, and researchers do not yet know whether humans can contract bird flu by drinking unpasteurized raw milk from infected cows.
Mark McAfee, owner of Raw Farm USA in Fresno, California, he can't keep his unpasteurized products in stock.
"People are seeking raw milk like crazy," he told AP, noting that no bird flu has been detected in his herds or in California. "Anything that the FDA tells our customers to do, they do the opposite."
The federal government has not banned milk from infected herds from being sold, but officials advised farmers not to sell milk from cattle that have been infected. They've also recommended that milk from asymptomatic cows that were exposed gets pasteurized before being sold or fed to animals.
FDA testing has shown the pasteurization process is effective at inactivating the virus. The agency continually tests samples of the U.S. milk supply to ensure that pasteurized milk sold in grocery stores is safe for consumption.
The FDA has found high viral loads of H5N1 avian influenza in the raw milk of some of the infected herds, which are located across nine U.S. states. The United States Department of Agriculture has saidtesting indicates the disease may be spreading through dairy farms as healthy cows come in contact with the raw milk of infected cows. But officials are still studying to determine exactly how the virus is moving.
Somecats died after drinking the raw milk of cows infected with H5N1, according to areportpublished in the CDC journal Emerging Infectious Diseases.
So far, a Texas farmworker is the only personin the U.S. currently known to have contracted the virus after exposure to infected cows. His case was mild and presented as conjunctivitis. Officials have not publicly reported how the transmission occurred.
The CDC has said the bird flu virus currently poses a "low risk to the general public" but the agency also said H5N1 has "pandemic potential." Health officials say they are working to be prepared for the possibility of a bird flu outbreak in humans.
"Unless you're in close contact with potentially infected animals or you're drinking unpasteurized milk, the risk to you right now is very low," said CBS News chief medical correspondent Dr. Jon LaPook.
"But remember, things can change," he added, "especially with viruses ... they can mutate, they can change, we've seen that happen. And that is why there is such concern among public health officials and others, and why the CDC and others are really trying to stay on top of this."
Rhona Tarrant contributed reporting.
Laura Doan is a reporter and associate producer for "Prime Time with John Dickerson." She covers the climate crisis, science and technology, and U.S. politics.
Cows have entry portals for both human and bird flus. This new finding may mean that cattle could host both types of flus at once. The two viruses could then swap parts to create a new type of influenza, maybe even one that could cause a pandemic.
Cattle have three types of influenza A receptors entry portals viruses use to infect host cells veterinarian Charlotte Kristensen and colleagues report May 3 at bioRxiv.org. One portal is like a receptor that decorates human cells. Another is like that found in chickens. And the third resembles receptors from ducks.
One of those avian receptors may have allowed a virus from a wild bird to infect a dairy cow in Texas, leading to the current H5N1 bird flu outbreak in cattle.
Researchers have long thought cattle were resistant to influenza A, says Kristensen, of the University of Copenhagen. Some cows have been infected in lab studies, and there have been suggestions that cows might sometimes catch human seasonal influenza. But it surprised many experts when H5N1 bird flu was found in dairy cattle and in grocery store milk this spring (SN: 4/25/24).
In the new study, Kristensen and colleagues tested whether cows have receptors that bird flu viruses can use to infect their cells. Not only did the team find such entry portals but also found that the receptors, especially the duck version, were abundant in the mammary glands, at low levels in the respiratory tract and at very low levels in the brain. That fits with the description of the illness in cows, Kristensen says, which affects milk production but doesnt seem to make most cows very sick.
Its still unclear how an infection gets to the udder. Its possible the virus enters through the teat via contaminated milking machines. But none of the receptors are present in the ducts leading up to the milk-producing glands, Kristensen says. The virus might get to the mammary glands through the blood, but so far there are no reports of the virus in cows blood, she says.
These are just preliminary results, Kristensen says, but still important, because right now we really [dont] know very much about cattle and influenza viruses.
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Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a masters degree in science journalism from Boston University.
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HUNTSVILLE, Ala. (WHNT) Federal and state officials continue to monitor the path of avian flu in 11 U.S. states. A list that does not include Alabama has reported dairy cattle affected with bird flu.
The Food and Drug Administration reports that last week nearly 300 tests of retail dairy products found no traces of a viable virus.
The USDA has said pasteurization appears to be consistently effective against the virus in milk from infected cows. The USDA also said it is expanding testing of the milk supply at different points in the supply chain.
Alabama health and agriculture officials say they are monitoring the flu reports from around the country.
I think it is very important that we acknowledge that there are no cases of avian influenza in cattle at this point in Alabama, that we know of, said Dr. Dee Jones, veterinarian with the Alabama Department of Public Health. And there are certainly no people. Even across the nation, 12 or 13 states impacted weve only had one positive person.
So, I think what that indicates that this virus and everything we know about this virus at this point is that it is not likely to infect people. Now unfortunately it is a flu virus and flu viruses can reassort to become more infective to people.
Jones said state health and agriculture officials have worked to ensure personal protective equipment, PPE, is available per the CDCs recommendation for dairy farm producers in the event an avian flu case is identified. Dr. Jones stressed gathering PPE isnt a prediction the virus is coming here through cattle, but it is a precaution.
U.S. health officials say they are still assessing how the virus transfers from cow to cow. Dr. Jones said backyard farmers need to continue to monitor the health of their chickens, consult with their veterinarian if they see a problem, and avoid their chickens eggs if the birds appear sick.
The USDA also advises against drinking raw milk. Alabama saw a couple of sizable bird flu outbreaks in poultry in late 2023, but no cases have been reported this year.
Its been more than two years since avian flu was first detected in Maine and two months since the virus appeared in dairy cattle west of New England. Heres what we know about its presence in Maine and risk to the state right now.
The respiratory virus is known scientifically as Highly Pathogenic Avian Influenza H5N1. Highly pathogenic means the virus is very contagious.
It affects all kinds of birds, is typically deadly and has typically spread to commercial and backyard flocks through migrating wild birds. This spring, it was detected in dairy cattle in the western United States.
Infected birds carry the virus in their saliva and mucus. It can spread quickly through a flock this way.
Symptoms in poultry include swollen heads, blue coloration of combs and wattles, lack of appetite, respiratory problems and diarrhea, with a significant drop in egg production.
The states risk of avian flu is rated moderate by the Maine Department of Agriculture, Conservation and Forestry.
Three outbreaks have been detected in Maine in 2024 as of May 15. All cases were in backyard flocks of 40-60 birds. The Centers for Disease Control and Prevention reported two sites in January one in Kennebec and one in York counties and one in March in Knox County.
No detections have been confirmed in dairy cattle in Maine or New England.
Several seals and a red fox have also been found carrying the virus in Maine.
The CDC reports it does not have sufficient data on the virus presence in Maine wastewater. The virus has been detected in wastewater in minimal amountsin the rest of New England.
It is possible to come down with avian flu, especially if you regularly handle poultry, but agencies say the risk is low right now. One case in Texas is the only confirmed human infection so far, and the person has recovered.
Symptoms in humans are similar to a typical flu, including coughing, headaches, fever, chills, sore throat and congestion. If youve been exposed to avian flu and develop symptoms, the Maine Department of Health and Human Services recommends calling your doctor and the Maine CDCs 24-hour consultation line at 1-800-821-5821.
Virus remnants have been found in commercial milk, which the U.S. Food and Drug Administration said is nota health risk in pasteurized dairy.
The administration has found high levels of the virus in raw milk outside of Maine, and generally recommends against drinking it, but has not confirmed the risk of consuming virus particles in the milk. It believes the commercial milk supply is safe.
Raw milk and milk products are legal for state-licensed producers to sell in Maine. It is not federally legal, meaning the organization leaves regulation up to each state.
Milk production is regulated in Maine by the Maine Department of Agriculture, Conservation and Forestry. Department staff are analyzing federal updates and working with organizations in Maine and at the federal level, according to spokesperson Jim Britt. Updates are available on the departments website.
Sick birds and unusual deaths can be reported to the state veterinarian or through this formand at the USDAs hotline at 1-866-536-7593.
Agencies recommendtaking biosecurity steps around birds and livestock, such as keeping your distance from wild birds, even if they dont look ill, and avoiding direct contact with sick poultry. The Maine Department of Health and Human Services warns against visiting other peoples flocks.
Covering your poultrys outdoor spaces can reduce the risktheyll come into contact with the virus from wild birds.
Separate guidancefor hunters issued by the United States Department of Agriculture includes processing birds in the field when possible and using separate clothing and tools to clean them. Throw out guts and feathers in a secure place, disinfect tools and wash your hands thoroughly before touching your nose or mouth.
Elizabeth Walztoni covers rural life for the Homestead section. She came to the Bangor Daily News from the Damariscotta/Newcastle desk of the Lincoln County News. Before becoming a reporter, she worked... More by Elizabeth Walztoni
As bird flu continues to spread among America's dairy cows, the Centers for Disease Control and Prevention has made it easier for the public to track how close the outbreak might be to their area.
Drawing on data from 600 wastewater sampling sites across the U.S., the federal agency created an interactive map showing current influenza A levels in comparison to the same sites' levels during flu season last year. The CDC said once virus levels are at the 80th percentile or higher, it'll work to better understand why cases are rising there.
Data from the two most recent weeks of wastewater samples show 230 sites across 34 states met the criteria for influenza A virus analysis, and three sites from three states Saline County in Kansas, Pinellas County in Florida, and Kane County in Illinois were at the high level, being greater than the 80th percentile.
The one disclaimer with the new dashboard is that wastewater monitoring methods at these sites don't have the ability to distinguish which subtype of influenza A is detected, like whether it's H5N1 bird flu or the seasonal flu virus. But the CDC says most of the latter flu time activity peaks between December and February, so new spikes in wastewater influenza A detection are likely indicative of a bird flu outbreak in the area.
Wastewater monitoring data also can't show where the influenza A originated, like whether it's from a human, an animal or an animal product. But the CDC says it has other surveillance systems to complement these lapses.
The bird flu virus was first confirmed in the U.S. on March 25 from dairy cattle in the Texas panhandle region. As of Wednesday, 42 herds in nine states have been affected by the virus.
USDA
However, dairy farmers have been reluctant to report outbreaks within their cattle, creating gaps within testing and tracking capabilities. This prompted a federal order to be put in place since April 29 requiring testing be done prior to interstate travel for lactating dairy cattle, and instating mandatory reporting of positive influenza A test results. The USDA also announced last week up to $28,000 in assistance to farmers who have been affected by the spread of the virus.
Since the first case, the CDC said it's monitored at least 260 people, with one case in a Texas dairy worker being identified as H5N1. The person, who is only the second person to ever contract the virus in the U.S., has since recovered.
Rare human bird flu infections can occur when the virus gets into a person's mouth, nose, eyes or is inhaled, according to the CDC. Most cases have occurred when a person has close or unprotected contact with sick birds or their habitats. Ensuing illnesses can range in severity from no symptoms to mild infections or severe pneumonia that result in death, the agency said.
The CDC says the current risk to the general public amid the bird flu outbreak is low, but it recommends people exposed to birds or infected mammals should be cautious.
Grocery store milk containing viral remnants is still safe due to the pasteurization process killing the virus, according to the FDA, but it's unknown whether the same can be said for raw milk.
Both the CDC and FDA recommend against drinking raw milk because high levels of H5N1 have been found in supplies, and if a person consumes raw milk containing the live virus, the person can theoretically become infected "by the virus binding to a limited amount of virus receptors in the upper respiratory tract or by aspiration of virus into the lower respiratory tract where receptors that A(H5N1) viruses can bind to are more widely distributed," the CDC says.
Despite the warning, NielsenIQ reported that since March 25 weekly sales of raw milk have increased by 21% to 65% compared to the same periods a year ago.
Nik Rajkovic / news@whmi.com
New research from Michigan State University will study the effects of a recent highly pathogenic avian influenza A virus (H5N1) outbreak on dairy cattle reproduction and milk production, as well as transmission of the disease and ways to mitigate it.
Support for the new project has been provided through two sources, each covering half of the $168,000 total:
Annual capacity funding through MSU AgBioResearch from the U.S. Department of Agricultures (USDA) National Institute of Food and Agriculture.
Capacity funding through the Michigan Alliance for Animal Agriculture, a partnership among MSU, Michigan animal agriculture industries and the Michigan Department of Agriculture and Rural Development (MDARD).
The project is co-led by Catalina Picasso, Zelmar Rodriguez and Annette OConnor, faculty members in the College of Veterinary Medicines Department of Large Animal Clinical Sciences (LCS). Picasso is a veterinarian and epidemiologist, specializing in transboundary infectious diseases in both livestock and wildlife animal populations. Rodriguez is a dairy health epidemiologist and dairy extension faculty member.
OConnor is a world-renowned veterinarian and expert in the application of quantitative epidemiology to improve policy on food safety, animal health and welfare, and veterinary practices.
According to the USDA, as of mid-May, H5N1 infections have been detected in dozens of dairy herds across Colorado, Idaho, Kansas, Michigan, New Mexico, North Carolina, Ohio, South Dakota, and Texas.
The virus, which was first detected in domestic birds in the U.S. in 2022 but not until recently in cattle, has been identified in unpasteurized milk, as well as swabs and tissue samples from sick cattle.
Symptoms may include reduced milk production, decreased appetite, and changes in milk color and consistency.
Immediately upon the onset of the H5N1 outbreak in Michigan dairy cattle, MSU AgBioResearch, the College of Veterinary Medicine and MDARD began conversations about research questions that when answered could inform policy and management strategies to help prevent transmission within and across dairy herds, said James Averill, assistant director of MSU AgBioResearch and leader of the organizations animal agriculture initiatives.
This research will enable the dairy industry to better understand H5N1 and the impacts on dairy herds over time.
The research team will seek to answer several key questions, such as:
Impact: What are the short- and long-term effects of the disease on reproduction and milk production?
At the herd level: What factors influence the likelihood of herds becoming infected?
At the cow level: What increases or decreases the likelihood of cows becoming infected?
Transmission: How is the virus spreading within and between herds?
Theres still an enormous amount of information we dont know, OConnor said.
This outbreak underscored the critical need to understand the dynamics, impact and prevention of H5N1 among the cattle population. We are fortunate to be able to ground this research in on-farm studies, working closely with MDARD to access farms that have had herds test positive for the virus.
The team plans to conduct five studies on farms with H5N1-positive animals. They will study lactating cows, dry cows and calves, collecting blood, nasal swabs and milk samples to be tested. All H5N1 testing is being performed by the MSU Veterinary Diagnostic Laboratory, the only laboratory in Michigan approved by the USDA to test for highly pathogenic avian influenza in any species.
Additionally, researchers will examine milking equipment for H5N1 presence and compare testing accuracy between pooled and individual samples.
Data from Michigan farms will be combined with findings from other universities nationwide for a comprehensive analysis. Were trying to understand how long animals are shedding the virus and how long the virus stays active, OConnor said.
For example, if we were to find that cattle are often positive on nasal swabs, we might conclude that nose-to-nose contact is a common route of transmission. Likewise, we may see that some samples come back negative quite often and show that those routes are much less likely. The overall goal is to equip our producers with the information needed to make informed decisions on how to best protect their cattle, and by extension, animal safety more broadly.
