The ongoing outbreak of bird flu has infected at least one person in the U.S. and has raised questions about how safe poultry and eggs are to eat right now.
So far, there have been no reported cases of spread among people, or of a person contracting this strain of avian influenza (also known as H5N1) from contaminated egg or poultry products, according to the U.S. Centers for Disease Control and Prevention (CDC). The CDC says that the current public health risk is low.
Here's what scientists know right now about bird flu and food safety.
The largest producer of eggs in the country, Cal-Maine Foods in Texas, temporarily stopped production at one of its facilities on Apr. 2 after H5N1 was identified there. The company also culled more than 3% of its flock in response to the outbreak.
Eggs from infected chickens are unlikely to be on supermarket shelves, the FDA says. Thats because in the time that it takes to detect an avian flu virus in a flock of egg-laying chickens, 99.99% of eggs would not have reached store shelves yet, since they would still be in the process of being distributed. That prediction comes from a model for estimating the risk of human exposure from avian flu outbreaks that was developed by the U.S. Department of Agriculture (USDA) and the U.S. Food and Drug Administration (FDA) in 2010. According to that assessment, even if an infection among chickens was discovered after eggs had hit supermarket shelves, more than 98% of potentially contaminated eggs could be removed from stores after a recall was issued.
Read More: Is Eating a Plant-Based Diet Better For You?
Another safeguard: pasteurization inactivates viruses in eggs and therefore eliminates most risk to human health. Properly handling eggsincluding avoiding cross contamination of any raw products with other foodsand cooking them at least until the yolks and whites are firm will further reduce any risk of infection.
Like it is with eggs, the risk of buying infected chicken at the grocery store is very low, according to the USDA and FDA. The model predicted a 95% probability that infected poultry would not make it to stores, since the virus would lead to relatively high mortality among the chickens, and farmers would be aware of the infection before the poultry was prepared for sale. However, the scientists determined that there is a 5% chance that infected chickens reaching market size would be slaughtered and sold before the virus was detected.
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The best way to prevent that from happening is to increase testing of flocks on farms, the risk assessment concluded. Farmers can also detect illness in their flocks by monitoring how much feed the birds eat, since birds tend to eat less when they're sick. According to the risk assessment, keeping track of feed consumption can lead to a 96% chance that an infected chicken is not processed for market, and can reduce the risk of human disease by 23 fold, while checking for signs of sickness leads to a 95.5% chance that infected chickens are not processed for market and reduces the risk of human illness by 8-fold.
As an added safety measure, keep raw chicken away from uncooked foods and cook chicken to 165F, which likely inactivates any virus that could make people sick.
A strain of avian influenza that has killed millions of birds in recent years has now been detected in dairy cows in several states, prompting concerns about the safety of the U.S. dairy supply.
Federal health and agriculture officials released a statement last week stressing that there continues to be no concern about the safety of the commercial milk supply, while underscoring that the agencies are continuing to monitor the situation as it evolves.
Scientists know that bird flu can spread to humans when they come into contact with infected animals, including dead ones, without wearing protective gear, which seems to have been the case with a person recently infected in Texas. So far, there isnt any evidence to suggest that humans can contract bird flu by consuming food that has been pasteurized or cooked, said Benjamin Chapman, a professor and food safety specialist at North Carolina State University.
Thats not to say it couldnt happen, he said. Its just that we have a pretty robust history of it not happening. And thats good news.
However, there are a few key points that researchers are still working to understand, Dr. Chapman and other experts said, like just how widespread the current outbreak is in cows, or exactly how the virus spread to them. Public safety agencies have said that its not clear what risks surround unpasteurized products.
In the column of known versus unknown, theres a lot more in the unknown part, said Dr. Gail Hansen, a veterinary public health expert and independent public health consultant.
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Texas cows are believed to have directly transmitted an avian flu to other cows and one person, according to state agriculture and health officials.
The new evidence of mammal-to-mammal transmissions of a virus that is highly infectious and deadly for domestic birds is a troubling development in the yearslong outbreak. Research published last month by the U.S. Centers for Disease Control and Prevention warned that the occurrences need to be closely monitored to prevent a potential health crisis.
The virus may be changing and adapting to infect mammals, researchers concluded. Continuous surveillance is essential to mitigate the risk for a global pandemic.
The Texas Department of State Health Services announced the human infection Monday. The person worked closely with dairy cows that are thought to be infected, and he was likely infected directly by them.
We believe thats how it happened, said Lara Anton, a spokesperson for the department.
The persons only symptom is conjunctivitis commonly known as pink eye and he has been told to avoid contact with other people while he recovers, Anton said.
We think that the risk is low for public health in general, for people who are not working with sick cows, Anton said.
There is no evidence that the virus has changed in a way that makes it more transmissible to humans, federal officials have said.
It was the second infection of a person in the United States by the currently circulating bird flu, according to CDC data. The first was in Colorado in 2022 of someone who was directly exposed to infected poultry. That persons only symptom was fatigue.
The bird flu outbreak in dairy cattle in Texas, Kansas and potentially New Mexico was first reported last week by the U.S. Department of Agriculture. Migrating birds are the apparent sources of the initial infections, which were noticed, in part, because sick cows were producing thick and discolored milk.
On Friday, the USDA confirmed the disease in a Michigan dairy herd and said it was the result of sick cows from Texas being transported there before they showed symptoms.
There has not yet been evidence of cow-to-cow transmission of the virus in the Michigan herd, said Jennifer Holton, a spokesperson for the Michigan Department of Agriculture and Rural Development.
But in Idaho, where another dairy herd received cows from Texas, at least eight cows of the preexisting herd have been infected, according to preliminary test results.
That leads us to assume cow-to-cow transmission, said Sydney Kennedy, a spokesperson for the Idaho State Department of Agriculture.
The most significant impact so far on the affected dairy farms is a drop in milk production while infected cows recover. Federal rules forbid milk from sick cows to be processed for human consumption.
Early herd infections in Texas resulted in milk losses of up to 40% in herds for a week or more, the Texas Department of Agriculture said. However, those losses are too small to cause national milk shortages or higher prices for consumers, the USDA said.
The current bird flu outbreak started February 2022 in the United States and has since resulted in the culling of about 82 million birds in commercial and backyard flocks in 48 states, according to CDC data. Its effects have been most profound during spring and fall migrations of wild birds.
Despite the spring migration being underway this year, only seven U.S. flocks were infected in the past month for a total of about 32,000 birds. Nearly all of those were part of a commercial turkey flock in South Dakota.
This article first appeared in theIowa Capital Dispatch,a sistersite of the Nebraska Examiner in the States Newsroom network.
The discovery of H5N1 bird flu in U.S. cattle and the news that at least one person in Texas has been infected, apparently through contact with infected cows has taken scientists who study influenza by surprise.
But after absorbing their shock, several admitted there was evidence to suggest bovine infection could happen it just hadnt been reported with this particular strain of influenza virus until now.
The situation is evolving. But here are some questions we can answer now about the curious case of highly pathogenic H5N1 avian influenza in dairy cattle.
Cows from 12 dairy herds in five states have tested positive for H5N1. Those states are Texas (seven herds), Kansas (two), Michigan (one), New Mexico (one), and Idaho (one).
Is that the full extent of the problem?
Some experts believe its unlikely if only because people havent been looking for bird flu infections in cattle before now. It could have been infecting dairy cattle a year ago. We just never thought about looking for it, said David Swayne, an avian influenza expert who is now a private consultant after having worked for the U.S. Department of Agriculture for nearly 30 years.
Probably not, Swayne admitted.
In the 1990s, there were reports from the United Kingdom of cows that were infected with human flu viruses. And there is a type of influenza known as influenza D that cows are susceptible to. (Humans mainly contract influenza A and B viruses.)
As to infection with H5N1 specifically, there has been evidence for a while that it could occur at least in a laboratory setting. Scientists from the Friedrich-Loeffler-Institut, in Greifswald-Insel Riems, Germany, reported in 2008 that they had experimentally infected six calves with an H5 virus retrieved from an infected cat. All remained healthy but all sero-converted they developed antibodies that indicated that an infection had taken hold.
The list of species that this virus has been shown to be able to infect has grown substantially in the past couple of years, as widespread infection in wild birds has brought the virus to new parts of the globe.
As early as 2003 the virus was seen to be able to infect big cats, having infected tigers and snow leopards in a zoo in Thailand. Later it was seen to infect domestic cats and small carnivorous mammals like martens and mink. More recently, infected black bears, brown bears, polar bears, raccoons, skunks, and coyotes have been found; aquatic mammals like sea lions and seals have also been infected. USDA keeps a list of animal species in which infections have been detected here.
For some of these mammals, the route of infection is pretty obvious. Scavengers that feast on dead bird carcasses can become infected that way.
But cows? Experts believe the more likely route of infection here is via water or grasslands contaminated with virus by infected birds.
There is massive (unprecedented) exposure of wild carnivores (feasting on sick/dead birds) and potentially also other mammals (through contaminated water and surface areas, including grasslands), Ron Fouchier, an influenza virologist at Erasmus Medical Center in Rotterdam, the Netherlands, told STAT via email. The infected mammals get infected upon feeding/drinking, which is an alternative route of infection of mammals.
Richard Webby, an influenza virologist who heads the WHO Collaborating Center for Studies on the Ecology of Influenza in Animals at St. Jude Childrens Research Hospital in Memphis, Tenn., said infected birds and mammals shed large amounts of H5N1 virus, increasing the risk to other species. There is this elevated exposure, he said.
There have been no reports to date of infected herds, but people should be on the lookout, Swayne suggested.
Yes. The Centers for Disease Control and Prevention published alengthy analysisof the genome of the virus from the infected person. The CDCs conclusion: The small changes seen in the virus are similar to those seen in other instances where this H5N1 has infected people. Viruses with those changes havent been seen to trigger ongoing person-to-person spread.
Overall, the genomic analysis of the virus from this human case does not change CDCs risk assessment, the agency said. The overall risk to human health associated with the ongoing HPAI A(H5) outbreaks in poultry and detections in wild birds and cattle remains low.
First, the CDC said the pattern of infection in the person who only had conjunctivitis or pink eye and the low levels of virus in the collected sample suggest the individuals respiratory tract was not infected. Viruses that are spread by coughs and sneezes are easier to transmit than viruses that are not.
Second, the virus taken from the individual was very closely related to two candidate vaccine viruses seed strains for vaccine production that are already available to vaccine manufacturers. That suggests if a virus like this one started spreading among people, those seed strains could be used to produce vaccines that would be protective.
Third, the virus showed none of the genetic changes that are known to confer resistance to flu antiviral drugs. That means antivirals likely would be effective against this virus.
Yes, in theory. In practice, though, it shouldnt be an issue.
Infected cows shed virus in their milk. Farms that have detected H5N1 in their cows are supposed to destroy the milk produced by infected cows, so it should not make its way into the food chain. Even if some did, inadvertently, pasteurization would kill the viruses, the USDA says.
Unpasteurized milk from affected cows would pose a risk to people. But unpasteurized milk poses multiple risks to people and public health authorities recommend against its consumption.
Thats suspected, but it is uncertain at this point. The infected herd in Michigan had received cows recently from Texas.
Bird flu viruses are genetically structured to infect birds. They can occasionally spill over into mammals, but typically those infections should dead-end in those new hosts. The viruses would need to adapt to be able to transmit efficiently in the new species.
Viruses that mutate to be able to transmit in one species of mammals could find it easier to infect people. Thats why particular attention is paid when bird flu viruses are seen to infect people, or mammal species with which humans interact. An animal of particular concern is pigs.
Pigs are traditionally referred to as mixing bowls or mixing vessels for flu species, because they can be infected with bird flu viruses and with the flu viruses that infect people. If pigs become co-infected with various types of flu, the viruses can swap genes and form hybrids that can then spread from pigs to people. The 2009 H1N1 flu pandemic was caused by a virus that jumped from pigs to people.
Swayne said back in the early 2000s there were occasional reports from Asia of pigs being infected with the virus, but those events appeared to die out. Pigs are not among the list of mammals that have more recently been seen to be susceptible to the virus.
However, scientists have tried infecting pigs in laboratories, with differing results. German scientists reported in 2023 that only one of eight pigs they infected with a strain of H5N1 from a chicken developed antibodies that indicated there had been an infection. Those scientists used the same strain of H5N1 as was found to have infected the cows in the U.S., which goes by the awkward moniker 2.3.4.4b.
But more recently, scientists from the USDA reported that they were able to experimentally infect pigs, and some of the infected pigs transmitted the virus to uninoculated pigs housed with them, when using sample viruses taken from mammals raccoons and red foxes.
Almost undoubtedly.
Were doing science here. And science changes. And when the science changes, then our assessment may change, said Nirav Shah, principal deputy director of the Centers for Disease Control and Prevention.
This article has been updated to include findings from the CDC analysis of the virus that infected the Texas person, and that testing confirmed a cattle outbreak in Idaho.
A person in Texas has tested positive for the highly pathogenic avian influenza A virus (H5N1), also known as bird flu, the U.S. Centers for Disease Control and Prevention has confirmed. This individual, who was exposed to cattle that were believed to be infected with the virus, reported eye rednessa sign of conjunctivitisbut no other symptoms. The patient is being treated with antiviral medication and is recovering.
Avian flu has been ripping through farmed poultry and wild bird populations around the world in recent years. It has also infected mammalian species ranging from foxes, bears and seals to cats and dogs. And in recent weeks, infections have been found in cattle in five U.S. states: Kansas, Texas, Michigan, New Mexico and Idaho and Minnesota. There is no evidence of human-to-human transmission so far, and the CDC says the risk to the public remains low.
The new human case is the second known to occur in the U.S. The first was in 2022, when a person in Colorado tested positive for the virus via a nasal swab after having direct contact with infected poultry. That patient reported mild fatigue and later recovered. Previous cases of avian flu in humans were deadly, but they involved a different form of the virus than the one that is currently circulating.
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Scientific American talked to Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, about the latest human case and the risk to human health more broadly.
[An edited transcript of the interview follows.]
How worried should we be about the human bird flu case in Texas?
First of all, theres some clarification here. Neither of these two cases [in the U.S.] has been an actual influenza infection as you think of a respiratory infection. They both have been basically either a nasal swab detection, for the previous one, or in the case of this one, a conjunctivitisan eye infection. So this isnt classic influenza at all.
The first one was just someone who was tested routinely. They were working in a barn, depopulating the birds that were dying from flu, and they had some mild symptoms, and they just got tested. They dont know if the symptoms were related to it, and it could have been that the virus was just picked up in the nose because of just inhaling it in. The second case is a case of conjunctivitis. So thats not, again, unexpected in that there are receptor sites in the eye for influenza viruses.
Thats reassuring. How likely is the virus to spread more widely among people?
The risk assessment from both [the World Health Organization] and CDC remains that there is low risk for humans with this virus, and I support that. If you look at the cases that have occurred since 1997, when it first emerged in human cases Hong Kong, through to mid-2015 to 2016, those years were by far the highest-risk situation. Weve seen very few cases in humans since then. And part of that is that the virus has changedits mutated to the point of where it is infecting other mammalian species and birds at an increasing rate. But weve had no evidence yet that thats happened for humans or for pigs. And pigs would be the animal species that, to me, would be the sentinel that Id be most concerned about.
Why is H5N1 causing milder human infections now?
This virus just is not infecting lower parts of the respiratory tract in humans at this point. Now that can all change in a heartbeat with additional mutations. But at least for now, its not an issue.
Previously there have been fatal cases of avian flu in humans in other countries, however. What does that tell us about the risk of human spread?
Weve been here before. When we saw a major increase in transmission, in human cases, in Indonesia and Thailand and other countries in the 20032007 time period, the message was This is going to be a pandemic virus soon. Then nothing happened. Then, in 2012, I was at that time on the National Science Advisory Board for Biosecurity, and we had data presented to that group that essentially said, Were just one mutation away from the virus becoming a major pandemic virus. It didnt happen. Then, if you look at 2015, that was when we saw the major increase in cases in Africain Egypt, along the Nile River Valley, in people raising domestic ducks. That time there were [hundreds of] cases in Egypt alone that year in humans. And the thought was that, you know, its just imminent now that we're going to see an influenza pandemic from H5N1. Nothing happened.
And so I think that weve had lessons in the past to be careful about making the leap to this is going to happen. At the same time, you know, you have to keep your eye on it. With all the influenza viruses collectively, you have to sleep with one eye open every night if youre worried about a pandemic.
Why were some of those earlier cases of H5N1 so deadly?
The virus was able to reach receptor sites and cells deeper in the respiratory tract and cause human infection. And it was obviously a severe issue. But even then, we had no evidence these were person-to-person transmitted cases. The exposures were [traced] back to the animals. We havent seen any evidence of sustained human-to-human transmission.
Did the current case in the U.S. likely involve a person becoming infected because of contact with a cow?
I cant speak to which animal it was contact-wise, but that could very well be. There was some question as to whether or not there was also contact with birds on the same farm. So either way, its clearly an animal exposure.
How would we know if the virus was spreading more widely in people?
First, you have to have a confirmed case in a human of a respiratory-transmitted virus that then resulted in severe-to-moderate respiratory illnessand then you just start picking up additional human cases in that area.
Are scientists watching H5N1 closely to see how it evolves?
Were going to be tracking the virus to see is it changing genetically and if the [avian flu group] 2.3.4.4b is the same virus were seeing here with the wild birds. In the humans, we have not seen any changes in the virus yet that would support that its now more human-adapted. Thats going to be one thing well be looking for. The second thing is just looking at the epidemiology: Are there people who are in contact with potential cases? I say potential because we have not had a respiratory transmitted virus case yet in the U.S. So I think that will be important. If we see one, will we see others around it?
Could people become infected by consuming unpasteurized milk or undercooked meat from an infected cow or other animal?
Yeah, well, unpasteurized milk and cheeses I would surely avoid. But Ive been saying that for 50 years for a whole lot of other reasons, too, public-health-wise. Surely, this is just one more addition to that. I think the second thing is, of course, that, at this point, what data we have supports that pasteurization will kill the virus in the milk.
But could you actually become infected by drinking milk containing the virus?
We dont know. Will taking the virus down your throat, into your larynx, will that cause the exposure of the virus to cells with the right receptor sites? We dont know that yet. Its possible.
How is the fact that H5N1 is infecting cows and goats likely to affect the livestock industry?
I dont know. I mean, well know in the weeks ahead. This is the time of the year we expect to see migratory birds bringing the virus into many communities that have not seen the virus for months. And each time that happens it's kind of a throw at the genetic roulette table, and we'll see what happens. We don't know. But it's all the more reason why we need to be better prepared for the next pandemic.
At this point, again, the virus, as it is, I don't believe poses a major risk to humans. But that, as I said, could change overnight if there were mutational changes to the virus.
News that H5N1 avian influenza has breached another mammalian species this time dairy cows has taken the flu science community aback. Though cows previously had been seen to be susceptible to human flu viruses, and could be experimentally infected with H5 in a lab, the absence of cow involvement until now in H5s nearly 30-year history lulled scientists into thinking the species was outside the viruss remit.
Further elevating the concern this discovery has triggered is the fact that a dairy farm worker in Texas was infected with H5N1, though the unnamed individuals only symptom was conjunctivitis.
To put these developments in perspective, STAT turned to Dutch virologist Ron Fouchier, a leading expert on H5N1, for his assessment of these latest twists in the H5 saga. Fouchier, who studies avian influenza at the Erasmus Medical Center in Rotterdam, was at the center of a controversy about H5N1 in 2012, when a U.S. scientific advisory group moved to restrict publication of research he and a team at the University of Wisconsin-Madison had done separately to see what mutations would be needed for the virus to be able to spread efficiently among people, so-called gain of function research.
Fouchier takes little solace from the fact that current versions of H5N1 seem to infect people less frequently, and to cause mostly mild illness when they do. The global range of H5 viruses the sheer volume of the virus in nature and the numbers of mammals H5 has shown itself capable of sickening is unprecedented, he said, making anticipating its future path harder than ever to gauge.
A transcript of the conversation is below. It has been lightly edited for length and clarity.
(Note: A zoonosis or zoonotic event is the infection of a person with an animal virus, in this case H5N1. Reassortment is a process by which flu viruses swap genes in an infected species, giving rise to hybrid viruses that could behave differently than their parent viruses.)
Is it possible that weve seen the H5N1 evolve to become more dangerous to a bunch of other species, but less dangerous to us?
Its what Id like to think.
In the years after the first human cases of infections in Hong Kong in 1997 right up to 2015, we saw relatively large numbers of zoonotic events with H5N1, ending in 2015, with very large numbers in Egypt. There were quite large numbers of human cases, despite restricted replication of the virus around the globe.
Then, from 2014 onwards, the virus really started to spread massively with wild birds into Europe, crossing over into the U.S. two times now, also landing in Africa, spreading throughout Asia, all in wild migratory birds. Weve never seen such big outbreaks all across Europe and the Americas. And we see the number of zoonotic events decrease.
You have massive outbreaks in wild birds. It spreads over into poultry quite easily. But in humans we see lower numbers, and that to me suggests that the zoonotic risk has decreased. And I am more or less supported by that by noticing that in the Western world in England, in Russia, and in the U.S. most of the [human] cases that we have seen were not particularly severe.
After 2015, one thing that has happened is that these H5 viruses have continuously reassorted with wild bird avian influenza viruses. So what I think has happened is that these viruses are now better adapted to wild birds, but less adapted to poultry and to humans.
That increases the environmental load of virus on occasion. Theres different species, time and time again, where you see massive bursts of virus. And carnivores, they feast on [dead birds]. It could also increase the environmental virus load on grasslands where birds poop or in surface waters. And that could increase the risk even to non-carnivorous mammals like goats or cows.
That kind of gives me a feeling of reassurance.
It just provides an explanation where you wouldnt have to really take into account yet an increased zoonotic risk.
Of course, when we see this virus in a milking farm and you see incredibly high virus load in some milk cows and their milk, that is a new risk. Because Im not sure how familiar you are with the milking procedures, but theres very little that people do to prevent human contact with milk. During the milking process, theres massive generation of aerosol formation. If you have high amounts of aerosol with virus, the chances increase that you will get conjunctivitis.
Theres very little hygiene to protect the farmers that are milking. If people arent washing their hands a lot and somebodys infected with conjunctivitis, you could see how that could spread, couldnt you?
When we had an outbreak of [H7N7] bird flu in the Netherlands in 2003, we had 89 cases of human infection.
Is that when a veterinarian died?
Yes. The majority of cases then were conjunctivitis cases. There were very few respiratory illnesses, except for that one fatal case. But the cases of conjunctivitis were linked to direct contact with poultry, and not with human-to-human transmission.
There was only one investigation where two household members got conjunctivitis, and they shared a towel to wash their face. I think it is not very likely that you will see massive spread of conjunctivitis due to avian influenza. I dont think that its likely that it will spread human to human. Its more likely that it will spread from the animal source into humans.
I think you disagreed earlier when I used the word reassuring. But to me this pattern of becoming much better at infecting wild birds, and seemingly less inclined to infect people seems reassuring.
Well, let me explain why I dont think its too reassuring.
We have never seen this scale of infections in mammals, and in such diversity of mammals. We have now seen more than 40 species of mammals infected during the last outbreaks, which is unprecedented. We know that flu is unpredictable. But we also know that adaptation of virus to mammals is not a good thing.
Many of the adaptive mutations that you see occur when H5 has infected marine mammals, or foxes or martens or minks have been seen with the viruses that caused previous human pandemics. And that I find not reassuring. And with 40 species happening at the same time all over the world, sometimes with little option to intervene, that is not so reassuring to me.
What do you mean by options to intervene?
Well, if there are infections in cows, we can offer personal protective equipment to the milkers and we can offer antiviral drugs to people who start to develop symptoms or conjunctivitis. But when tens of thousands of seals wash up on your shore, what are you going to do? And how are you going to prevent onward spread?
And these are the animals that we see. What about the animals that we dont see so easily, like rats or mice? Whats happening? The large species we now know get infected easily. But the small species, we dont even know.
And so the high presence in nature, and the large number of infections I find concerning, despite the fact that we think current zoonotic risk is low. And thats because these viruses are changing. And we have no experience [of how H5 behaves] in all these species. We cant predict whats going to happen.
One of the things H5 has taught me is that its ever-changing, and just because it seems to infect people less frequently right now, that doesnt mean its always going to be that way.
Also the fact that the first human now is diagnosed with conjunctivitis is not a guarantee. Theres a small chance that if you have an infection in the eye, that you will actually get virus also in your respiratory tract. And then we know that if the virus ends up in your lower airways, you could develop pneumonia.
One case in a farmer who only develops conjunctivitis is not a reason to celebrate the fact that this virus is not virulent. Lets be careful now, and monitor the people and treat them with drugs as soon as you see that theres something more happening.
What are you working on now? What are you looking for?
I would like to know if there is indeed decreased zoonotic risk through the reassortment patterns.
How do you investigate that question? We identified reassortment patterns. And then we take one of the earlier parental viruses that didnt spread so well in wild birds and compare it to the current versions and inoculate different bird species, including ducks, or cell cultures. And you can look for all of the different variants, and how they vary in their replicative capacity in wild birds.
We can inoculate human organoid cells and see how permissive the cells are to the different variants, whether the early Asian variants that caused many zoonoses, whether they were, in fact, more prone to infect human tissue than the current viruses.
And if you see those same opposing patterns so more adaptation to wild birds, less efficient in infecting human cells that would explain the current situation compared to what weve seen before.
But of course, its important to note that were all doing our research with our hands tied behind our back because of the gain-of-function issues. We have to be careful in what we do and how we design the experiments. So we can take natural viruses and show that the old viruses were less likely to infect wild birds and more likely to infect human cells, and the current virus is the other way around. But really getting to the bottom of things is getting harder and harder.
Is there anything youve been waiting for a chance to say but I havent asked the right question to elicit it?
Well, the questions are really about whats going on with the cows. And U.S. scientists and officials are hopefully going to resolve that quickly. How does this virus enter cows?
If there is cow-to-cow transmission, how does it work? Its clear that its dairy cows, and it could be that its due to the milking instruments that do not get cleaned enough. Its human driven cow-to-cow transmission. And if thats the case, you can stop it. You can try to actually clean your machine. So Im really looking forward to in-depth investigations, epidemiological investigations of how the cows get this disease.
It could also be from a common feeding source. So what are these cows being fed? Do they eat fresh grass? Do they eat hay from a common source that has been contaminated by birds being out there? I think this is really crucial information, because this is going to lead to what are the options to stop this outbreak.
SUMMARY
There is growing concern about the continuing spread of the highly contagious bird flu in the U.S. While federal health officials say the risk to humans is low, the virus has now spread to dairy cattle and sickened one person. William Brangham discussed more with Jennifer Nuzzo of the Pandemic Center at Brown Universitys School of Public Health.
View the transcript of the story.
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The Centers for Disease Control and Prevention urged medical practitioners on Friday to be on the lookout for people who might have contracted H5N1 bird flu from cows. The agency also urged state health departments to rapidly assess any suspected human cases, and recommended that dairy farms with confirmed or suspected outbreaks require workers to use personal protective equipment.
The recommendations were outlined in a health alert network advisory, or HAN in CDC parlance. The advisory is in response to the outbreak of H5N1 avian influenza in at least 16 dairy herds in six states across the country, which has led to at least one human infection so far.
Health care providers should ask themselves Could this be an H5N1 infection? if they are faced with a patient with what CDC called a relevant exposure history for instance, someone who works with dairy cows or lives with someone who works with dairy cows.
The illness should be considered for a range of mild, medium, and severe symptoms, from conjunctivitis to fever, shortness of breath, or pneumonia and/or organ failure, the CDC said.
Any patient suspected of having H5N1 flu should be isolated and cared for by medical professionals wearing protective equipment. Suspected cases should be started on the flu drug oseltamivir sold as Tamiflu even before test results confirming the infection have come back, the agency said.
The CDC said the individual known to have been infected, who worked on a dairy farm in Texas, is recovering from very mild symptoms effectively only conjunctivitis, sometimes called pink eye. The individual was treated with oseltamivir, as were people who had been in contact with that individual before the diagnosis. So far, there is no indication of secondary spread from this person.
No additional cases of human infection with HPAI A(H5N1) virus associated with the current infections in dairy cattle and birds in the United States, and no human-to-human transmission of HPAI A(H5N1) virus have been identified, the CDC advisory said.
HPAI is shorthand for highly pathogenic avian influenza, a term that describes how a flu virus behaves when it infects poultry. H5N1 viruses, which have been circulating on and off since 1997, decimate poultry flocks.
In cows, however, the illness has been mild to date, with infected animals showing a decline in milk production and decreased feed consumption. Dairy operations have been instructed to destroy milk from infected animals; milk from infected animals has been found to contain H5N1 viruses.
Even if contaminated milk were to make its way into the human food chain, pasteurization would destroy the viruses, the Food and Drug Administration has said. Consumption of raw milk or raw milk cheese from infected cows could pose a health risk and should be avoided, the CDC said.
Infected cows have been reported from Texas (eight herds), Kansas (three), New Mexico (two), and Idaho, Michigan, and Ohio (one apiece).
It is unclear if the virus has been transmitting from cow-to-cow through the respiratory route, in the way human flu spreads, or whether some aspect of dairy operations the movement of cattle from winter grazing grounds back to northern states, a lack of cleaning of milking equipment as it is moved from cow to cow is fueling spread of the virus.
The CDCs advisory said that analyses of viruses taken from the infected person, from cows, and from wild birds and poultry showed only small genetic changes. While minor changes were identified in the virus sequence from the patient specimen compared to the viral sequences from cattle, both cattle and human sequences lack changes that would make them better adapted to infect mammals, the HAN stated.
(NEXSTAR) A highly contagious strain of bird flu is ripping through flocks of major egg producers around the U.S. Its not just chickens being infected dairy cows have also tested positive, and one person in Texas is believed to have caught the virus after working with affected cattle.
As the Type A H5N1 influenza virus spreads, major egg producers have been forced to kill millions of chickens in attempts to contain the outbreak.
Its an economic loss for producers, and may soon become a burden on families grocery store bills.
We would expect to see some increase in prices because youre rapidly pulling a large number of potential eggs out of the market for the next 30 to 60 days, said Amy Hagerman, a professor of agricultural economics at Oklahoma State University.
Under normal circumstances, egg prices would usually be dropping after the Easter holiday, when demand is high. She doesnt expect that to be the case this year.
Plus, egg prices havent fully recovered from the ups and downs of the past two years. In 2022, when bird flu knocked out 10% of the countrys laying hens, prices skyrocketed.
Now, the average price of a dozen eggs is about $2.99, according to federal data. Thats worse than six months ago, when a carton typically ran about $2, but way better than January 2023, when a dozen eggs cost $4.82 on average.
While egg prices start creeping higher if the avian influenza outbreaks grow, the situation is different when it comes to dairy products.
Dairy farmers in Texas first became concerned three weeks ago when cattle started falling ill with what officials called mystery dairy cow disease, Texas Department of Agriculture Commissioner Sid Miller said. Milk production fell sharply and the cows were lethargic and werent eating much.
We hadnt seen anything like it before, he said. It was kind of like they had a cold.
With cattle, the virus doesnt appear to be nearly as deadly or contagious as it is with poultry, Hagerman said. If this virus gets into a poultry block, every animal is infected within a very short period of time. And were just not seeing that so far, or its not being reported by the cattle producers and by the veterinarians.
That means fewer deaths for dairy cattle, and fewer production disruptions for the dairy industry.
Poultry prices are also not being impacted at this point. While millions of egg laying chickens have been depopulated, commercial broiler operations chickens raised for their meat have not been greatly affected. Some turkey flocks have been impacted.
And while eggs may be more expensive in the coming months, they will be just as safe to eat as ever. Pasteurization of both eggs and milk kills the virus.
The Associated Press contributed to this report.
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Posted: April 04, 2024
Confirmation that a dangerous form of bird flu is circulating among U.S. dairy cattle has raised questions among dairy producers and consumers on both sides of the border.
Dairy and beef farmers are implementing biosecurity measures to keep H5N1 out of their herds, while Canadians are understandably concerned about what these outbreaks could mean for food safety.
So what is the scope of these dairy cattle outbreaks, and how is Canada impacted? And is it safe to consume milk and other dairy products?
In the last week, American officials have identified highly pathogenic avian influenza, or H5N1 bird flu, in roughly a dozen dairy cattle herds across six states: Idaho, Kansas, Michigan, New Mexico, Ohio, and Texas.
Scientists told CBC News it appears to be the first time H5N1 has infected cows. But the outbreaks weren't entirely unexpected. Bird flu exploded globally two years ago, and numerous wild and domestic animal species have been infected, including chickens, goats, and other farmed animals.
There have been sporadic human infections, and deaths, including a mild case in Texas in an individual who had contact with cattle the second-ever bird flu infection reported in the U.S.
While the dairy cattle outbreaks are new and raise important questions about spread across species, outbreaks among poultry are far bigger.
More than 80 million U.S. chickens have been affected by H5N1 across 48 states, the latest U.S. Centers for Disease Control and Prevention (CDC) data shows.
And Canada is experiencing a similar issue, with at least 11 million birds impacted country-wide, according to federal figures.
Not that we know of, though both farmers and federal officials are watching for it.
So far, the Canadian Food Inspection Agency (CFIA) has not detected H5N1 in dairy cattle or other livestock in Canada, and is "monitoring the situation closely," the agency said in a recent statement.
But bird flu experts suspect it's heading our way or already here.
"There's no reason to think that there would be infected birds near cattle in the U.S. and not in Canada, especially when you have multiple states infected," said Dr. Scott Weese, a veterinarian and researcher with the University of Guelph Ontario Veterinary College.
"So it's not unreasonable to think that we've had infections in Canada."
WATCH | Human bird flu case linked to U.S. dairy cattle outbreaks:
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The CFIA said the United States Department of Agriculture (USDA) shared that bird flu virus was detected in unpasteurized milk from sick dairy cattle in some U.S. states.
It's unclear whether drinking raw milk from an H5N1-infected cow would be risky, said Weese. But studies do show raw milk can carry all kinds of dangerous pathogens such as salmonella, E. coli, and listeria, all known for causing food poisoning.
"There are lots of other reasons not to drink raw milk, so this is maybe just one more reason to stay away," he said.
That being said, there are layers of protections in place to prevent tainted milk from ever reaching consumers.
"Dairy farmers control infectious diseases on their farm by isolating sick cows from the rest of the herd, effectively removing their milk from the general supply," noted Jenna Guthmiller, an assistant professor at the University of Colorado's department of immunology and microbiology, in a social media thread.
If tainted milk did somehow slip through in either the U.S. or Canada it would also go through pasteurizationbefore being sold. That specialized heating process is capable of killing any harmful pathogens, ensuring the milk is safe to drink.
And when it comes to the safety of other products, such as cheese, eggs, or meat, Weese stressed that flu viruses simply can't live for very long outside a living host.
"They're not very hardy," he said, adding that thoroughly cooking food definitely kills them.
The U.S. CDC notes that "the likelihood that eggs from infected poultry are found in the retail market is low and proper storage and preparation further reduce the risk."
As for beef, the U.S. cattle outbreaks are confined to dairy-producing cows, at least for now.
"It's not going to change my eating habits at all," said Weese.
"Canadian dairy producers already adhere to some of the highest biosecurity standards in the world," said the Dairy Farmers of Canada in a statement.
Several Canadian dairy farmers who spoke to CBC News also said they're implementing heightened measures in an attempt to keep bird flu out of their herds.
Kirk Jackson, a beef and dairy producer in St-Anicet, Que., said the potential for water source contamination is "almost zero" as farms like his use underground water sources. Workers also ensure spilled feed is cleaned quickly, to try and avoid attracting wild birds, and visitors to the farm are not currently allowed.
Still, the next few weeks could matter a lot, Jackson added, since spring bird migration is underway, bringing more flocks back north.
Seventh-generation dairy farmer Jason Erskine, in Hinchinbrooke, Que., said his farm uses screens to keep birds and vermin away from the cows but he's aware those measures aren't foolproof.
"They still find ways to get in," he said.
Lauren Pelley Senior Health & Medical Reporter
Lauren Pelley covers health and medical science for CBC News, including the global spread of infectious diseases, Canadian health policy, pandemic preparedness, and the crucial intersection between human health and climate change. Two-time RNAO Media Award winner for in-depth health reporting in 2020 and 2022. Contact her at: lauren.pelley@cbc.ca
