Review shows bird flu control strategies ‘not working’

Gaps in data highlight potential for silent spread

The Pirbright Institute

 

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Credit: The Pirbright Institute

A review of sustained mammal-to-mammal bird flu transmission in diverse species, led by The Pirbright Institute, shows global control strategies are not working.

Writing in Nature, researchers analysed whether outbreaks in European fur farms, South American marine mammals and United States dairy cattle raise questions about whether humans are next. Led by zoonotic influenza specialist Dr Thomas Peacock, the scientists evaluated how recent changes in the ecology and molecular evolution of H5N1 in wild and domestic birds increase opportunities for spillover to mammals.

They also weighed various evolutionary pathways that could turn the global H5N1 influenza panzootic into a human pandemic virus.

“Influenza A viruses (IAV) have caused more documented global pandemics in human history than any other pathogen. Historically, swine are considered optimal intermediary hosts that help avian influenza viruses adapt to mammals before jumping to humans,” said Dr Peacock, who investigates the drivers of the current H5N1 avian influenza panzootic. “However, the altered ecology of H5N1 has opened the door to new evolutionary pathways.”

The review highlights potential gaps in control mechanisms, including a reluctance to engage with modern vaccine and surveillance technologies and a dearth of data collection around the transmission of H5N1 between cows and to humans on US dairy farms.

Whilst previous generations of US cattle producers had eradicated foot-and-mouth disease by rapidly sharing epidemiological data, the authors say months of missing data is leaving researchers, veterinarians, and policy makers in the dark.

“H5N1 is a reportable disease in poultry, but not mammals, in the US. The US Department of Agriculture requires H5N1 testing only in lactating cattle prior to interstate movement,” said Dr Peacock.

Current practices for H5N1 testing in wildlife focus on carcasses, not monitoring animals whilst alive, the paper notes, providing opportunities for variants of H5N1 to spread silently undetected.

“What keeps scientists up at night is the possibility of unseen chains of transmission silently spreading through farm worker barracks, swine barns, or developing countries, evolving under the radar because testing criteria are narrow, government authorities are feared, or resources are thin.”

An evolutionary process of “genomic reassortment” in viruses with segmented genomes is driving the global panzootic outbreak. When two or more viruses co-infect a single host, they can swap entire segments during genome replication to create novel hybrids.

The reassortment between H5N8 and low pathogenicity avian influenza (LPAI) viruses that generated the panzootic H5N1 virus in the Americas is believed to have occurred in Europe or central Asia around 2020, infecting South American marine mammals and US dairy cattle.

The writers say the prospect of H5N1 becoming continually present in Europe and the Americas is a turning point for High Pathogenicity Avian Influenza (HPAI).

“New control strategies are needed, including vaccination. Influenza vaccines are licensed for poultry that reduce disease burden, but do not prevent infection and have varying degrees of success.”

Stocks of H5 vaccine that are antigenically related to circulating viruses are available and could be produced at scale using mRNA platforms if H5N1 begins spreading in humans, the authors note.

“The severity of a future H5N1 pandemic remains unclear. Recent human infections with H5N1 have a substantially lower case fatality rate compared to prior H5N1 outbreak in Asia, where half of people with reported infections died. The lack of severity in US cases may be due to infection through the eye, rather than through viral pneumonia in the lung.”

Older people appear to have partial immunity to H5N1 due to childhood exposure, whereas younger people born since the 1968 H3N2 pandemic may be more susceptible to severe disease in a H5N1 pandemic.

Dr Peacock’s work is funded by UKRI Biotechnology and Biological Sciences Research Council (BBSRC) via the Pirbright Institute’s Strategic Programme Grants (ISPGs)  and the UK Medical Research Council / Department for Environment, Food and Rural Affairs FluTrailMap One Health consortium, and the BBSRC/DEFRA ‘FluTrailMap’ consortium.

Read the Paper: https://www.nature.com/articles/s41586-024-08054-z

DOI: 10.1038/s41586-024-08054-z

 

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Journal

Nature

DOI

10.1038/s41586-024-08054-z 

Method of Research

Literature review

Article Title

The global H5N1 panzootic in mammals

Article Publication Date

24-Sep-2024

Bird Flu Is Bad for Poultry and Dairy Cows. It’s Not a Dire Threat for Most of Us — Yet.

2024/05/03

Headlines are flying after the Department of Agriculture confirmed that the H5N1 bird flu virus has infected dairy cows around the country. Tests have detected the virus among cattle in nine states, mainly in Texas and New Mexico, and most recently in Colorado, said Nirav Shah, principal deputy director at the Centers for Disease Control and Prevention, at a May 1 event held by the Council on Foreign Relations.

A menagerie of other animals have been infected by H5N1, and at least one person in Texas. But what scientists fear most is if the virus were to spread efficiently from person to person. That hasn’t happened and might not. Shah said the CDC considers the H5N1 outbreak “a low risk to the general public at this time.”

Viruses evolve and outbreaks can shift quickly. “As with any major outbreak, this is moving at the speed of a bullet train,” Shah said. “What we’ll be talking about is a snapshot of that fast-moving train.” What he means is that what’s known about the H5N1 bird flu today will undoubtedly change.

With that in mind, KFF Health News explains what you need to know now.

Q: Who gets the bird flu?

Mainly birds. Over the past few years, however, the H5N1 bird flu virus has increasingly jumped from birds into mammals around the world. The growing list of more than 50 species includes seals, goats, skunks, cats, and wild bush dogs at a zoo in the United Kingdom. At least 24,000 sea lions died in outbreaks of H5N1 bird flu in South America last year.

What makes the current outbreak in cattle unusual is that it’s spreading rapidly from cow to cow, whereas the other cases — except for the sea lion infections — appear limited. Researchers know this because genetic sequences of the H5N1 viruses drawn from cattle this year were nearly identical to one another.

The cattle outbreak is also concerning because the country has been caught off guard. Researchers examining the virus’s genomes suggest it originally spilled over from birds into cows late last year in Texas, and has since spread among many more cows than have been tested. “Our analyses show this has been circulating in cows for four months or so, under our noses,” said Michael Worobey, an evolutionary biologist at the University of Arizona in Tucson.

Q: Is this the start of the next pandemic?

Not yet. But it’s a thought worth considering because a bird flu pandemic would be a nightmare. More than half of people infected by older strains of H5N1 bird flu viruses from 2003 to 2016 died. Even if death rates turn out to be less severe for the H5N1 strain currently circulating in cattle, repercussions could involve loads of sick people and hospitals too overwhelmed to handle other medical emergencies.

Although at least one person has been infected with H5N1 this year, the virus can’t lead to a pandemic in its current state. To achieve that horrible status, a pathogen needs to sicken many people on multiple continents. And to do that, the H5N1 virus would need to infect a ton of people. That won’t happen through occasional spillovers of the virus from farm animals into people. Rather, the virus must acquire mutations for it to spread from person to person, like the seasonal flu, as a respiratory infection transmitted largely through the air as people cough, sneeze, and breathe. As we learned in the depths of covid-19, airborne viruses are hard to stop.

That hasn’t happened yet. However, H5N1 viruses now have plenty of chances to evolve as they replicate within thousands of cows. Like all viruses, they mutate as they replicate, and mutations that improve the virus’s survival are passed to the next generation. And because cows are mammals, the viruses could be getting better at thriving within cells that are closer to ours than birds’.

The evolution of a pandemic-ready bird flu virus could be aided by a sort of superpower possessed by many viruses. Namely, they sometimes swap their genes with other strains in a process called reassortment. In a study published in 2009, Worobey and other researchers traced the origin of the H1N1 “swine flu” pandemic to events in which different viruses causing the swine flu, bird flu, and human flu mixed and matched their genes within pigs that they were simultaneously infecting. Pigs need not be involved this time around, Worobey warned.

Q: Will a pandemic start if a person drinks virus-contaminated milk?

Not yet. Cow’s milk, as well as powdered milk and infant formula, sold in stores is considered safe because the law requires all milk sold commercially to be pasteurized. That process of heating milk at high temperatures kills bacteria, viruses, and other teeny organisms. Tests have identified fragments of H5N1 viruses in milk from grocery stores but confirm that the virus bits are dead and, therefore, harmless.

Unpasteurized “raw” milk, however, has been shown to contain living H5N1 viruses, which is why the FDA and other health authorities strongly advise people not to drink it. Doing so could cause a person to become seriously ill or worse. But even then, a pandemic is unlikely to be sparked because the virus — in its current form — does not spread efficiently from person to person, as the seasonal flu does.

Q: What should be done?

A lot! Because of a lack of surveillance, the U.S. Department of Agriculture and other agencies have allowed the H5N1 bird flu to spread under the radar in cattle. To get a handle on the situation, the USDA recently ordered all lactating dairy cattle to be tested before farmers move them to other states, and the outcomes of the tests to be reported.

But just as restricting covid tests to international travelers in early 2020 allowed the coronavirus to spread undetected, testing only cows that move across state lines would miss plenty of cases.

Such limited testing won’t reveal how the virus is spreading among cattle — information desperately needed so farmers can stop it. A leading hypothesis is that viruses are being transferred from one cow to the next through the machines used to milk them.

To boost testing, Fred Gingrich, executive director of a nonprofit organization for farm veterinarians, the American Association of Bovine Practitioners, said the government should offer funds to cattle farmers who report cases so that they have an incentive to test. Barring that, he said, reporting just adds reputational damage atop financial loss.

“These outbreaks have a significant economic impact,” Gingrich said. “Farmers lose about 20% of their milk production in an outbreak because animals quit eating, produce less milk, and some of that milk is abnormal and then can’t be sold.”

The government has made the H5N1 tests free for farmers, Gingrich added, but they haven’t budgeted money for veterinarians who must sample the cows, transport samples, and file paperwork. “Tests are the least expensive part,” he said.

If testing on farms remains elusive, evolutionary virologists can still learn a lot by analyzing genomic sequences from H5N1 viruses sampled from cattle. The differences between sequences tell a story about where and when the current outbreak began, the path it travels, and whether the viruses are acquiring mutations that pose a threat to people. Yet this vital research has been hampered by the USDA’s slow and incomplete posting of genetic data, Worobey said.

The government should also help poultry farmers prevent H5N1 outbreaks since those kill many birds and pose a constant threat of spillover, said Maurice Pitesky, an avian disease specialist at the University of California-Davis.

Waterfowl like ducks and geese are the usual sources of outbreaks on poultry farms, and researchers can detect their proximity using remote sensing and other technologies. By zeroing in on zones of potential spillover, farmers can target their attention. That can mean routine surveillance to detect early signs of infections in poultry, using water cannons to shoo away migrating flocks, relocating farm animals, or temporarily ushering them into barns. “We should be spending on prevention,” Pitesky said.

Q: OK it’s not a pandemic, but what could happen to people who get this year’s H5N1 bird flu?

No one really knows. Only one person in Texas has been diagnosed with the disease this year, in April. This person worked closely with dairy cows, and had a mild case with an eye infection. The CDC found out about them because of its surveillance process. Clinics are supposed to alert state health departments when they diagnose farmworkers with the flu, using tests that detect influenza viruses, broadly. State health departments then confirm the test, and if it’s positive, they send a person’s sample to a CDC laboratory, where it is checked for the H5N1 virus, specifically. “Thus far we have received 23,” Shah said. “All but one of those was negative.”

State health department officials are also monitoring around 150 people, he said, who have spent time around cattle. They’re checking in with these farmworkers via phone calls, text messages, or in-person visits to see if they develop symptoms. And if that happens, they’ll be tested.

Another way to assess farmworkers would be to check their blood for antibodies against the H5N1 bird flu virus; a positive result would indicate they might have been unknowingly infected. But Shah said health officials are not yet doing this work.

“The fact that we’re four months in and haven’t done this isn’t a good sign,” Worobey said. “I’m not super worried about a pandemic at the moment, but we should start acting like we don’t want it to happen.”

© Kaiser Health News

Federal government announces new initiatives to monitor, prevent bird flu

By Ernie Mundell, HealthDay News

The illness is typically not fatal in bovines, but monitoring and prevention on the nation's farms is costly, and the U.S. Department of Agriculture said the aid will make it cheaper and easier for farmers to deal with H5N1 when it is discovered infecting a herd.

 Photo by Adobe Stock/HealthDay News


H5N1 avian flu is now infecting U.S. dairy cows and the federal government on Friday announced myriad initiatives aimed at preventing the virus' mutation and spread in humans.

The illness is typically not fatal in bovines, but monitoring and prevention on the nation's farms is costly, and the U.S. Department of Agriculture said the aid will make it cheaper and easier for farmers to deal with H5N1 when it is discovered infecting a herd.

"Today, USDA is announcing assistance for producers with H5N1 affected premises to improve on-site biosecurity in order to reduce the spread," the agency said in a statement from the Department of Health and Human Services. "In addition, USDA is taking steps to make available financial tools for lost milk production in herds affected by H5N1."

USDA also wants to safeguard the health of dairy workers, who could become human reservoirs for the H5N1 virus.

Right now, its very tough to transmit bird flu person-to-person, and only one human, a Texas dairy worker, is known to have contracted a (mild) case of the disease during the latest outbreak.

But the threat of H5N1 mutating inside people so that it can be easily transmitted weighs heavily on the minds of infectious disease experts. That's because -- in the rare cases around the world where it has occurred -- the illness has killed half of those infected.

So, USDA said it plans to now give $2,000 "per affected premises per month" to supply personal protective equipment to farm staff to help keep H5N1 infection in people at bay.

Money will also be earmarked to help train farm workers in biosecurity, and to cover the costs of protecting people such as milk haulers, veterinarians, feed truckers and AI technicians who often move between various farms.

Another $2,000 will be earmarked to help farms pay for "heat treatment to dispose of milk in a bio secure fashion," USDA said. "Heat treatment performed in accordance with standards set by FDA is the only currently available method considered to effectively inactivate the virus in milk."

Finally, $10,000 per farm will be budgeted to pay for veterinary bills incurred because of the need for H5N1 monitoring and testing, and for the care of infected cows.

"Taken together, these tools represent a value of up to $28,000 per premises to support increased biosecurity activities over the next 120 days," USDA and HHS said in a joint statement.

Compensating farmers

If milk is deemed to be at risk for infection and must be dumped, USDA will help "compensate producers for loss of milk production," the agency said.

"While dairy cows that have been infected with H5N1 generally recover well, and there is little mortality associated with the disease, it does dramatically limit milk production, causing economic losses for producers with affected premises," the USDA said.

The agency also plans to put in place safeguards that would limit the movement of dairy herds state-to-state, to help prevent the spread of H5N1.

"USDA will make $98 million in existing funds available ... to fund these initiatives," the agency said. "If needed, USDA has the authority, with Congressional notification, to make additional funds available."

Viral monitoring

The Department of Health and Homeland Security has also earmarked more than $101 million to better understand and help fight H5N1.

"Public and animal health experts and agencies have been preparing for avian influenza outbreak for 20 years," the agency said. "Our primary responsibility at HHS is to protect public health and the safety of the food supply, which is why we continue to approach the outbreak with urgency."

H5N1 outbreaks in animals will be closely monitored, and there will also be "CDC monitoring of the virus to detect any changes that may increase risk to people," HHS said.

"CDC has also asked health departments to distribute existing PPE stocks to farm workers, prioritizing those who work with infected cows," the agency added.

Additional CDC funding totaling $93 million is targeted "to bolster testing and laboratory capacity, surveillance, genomic sequencing, support jurisdictions and partner efforts to reach high risk populations and initiate a new wastewater surveillance pilot," according to the news release.

This will include the production of "one thousand additional influenza diagnostic test kits (equaling nearly around one million additional tests) for virologic surveillance."

Another $14 million is earmarked to further the genomic sequencing of viral strains by the CDC. It's especially important to "analyze circulating H5N1 viruses to determine whether current Candidate Vaccine Viruses (CVVs) would be effective and develop new ones if necessary," the news release said.

Finally, $3 million in extra funding is being targeted to more widespread and better testing of wastewater -- a valuable tool in monitoring the development and potential spread of new strains of H5N1.

More information

Find out more about avian flu at the U.S. Centers for Disease Control and Prevention.
ADVERTISEMENT


Copyright © 2024 HealthDay. All rights reserved.

What to know about H5N1 bird flu in humans as a girl dies in Cambodia and her father tests positive

Catherine Schuster-Bruce
Fri, February 24, 2023 

A strain of bird flu, H5N1, can transmit between humans but it's rare.

Peter Garrard Beck/Getty Images

A girl has died in Cambodia from bird flu, health officials said.


The girl's dad is infected, but we don't know if he caught it from her.


Experts have said the risk of the virus spreading among people is low.

An 11-year-old girl has died in Cambodia from bird flu, health authorities in the country said.

The girl initially fell ill with a high fever and cough on February 16 and later died in the National Children's Hospital in Phnom Penh, Cambodia's capital city, on Wednesday, the authorities said, per Reuters.

The case comes amid an outbreak of bird flu that has lead to the deaths of more than 200 million birds worldwide since early 2022, either from disease or mass culls, the World Organisation for Animal Health told Reuters.

The bird flu strain "H5 Highly Pathogenic Avian Influenza A" or "H5N1" has infected 868 people since it was first detected in humans in 1997, and 457 of those confirmed cases died, according to the World Health Organization. Officials in Cambodia said that the girl was the first human case in a Southeast Asian country since 2014, per Reuters.

Officials believe that the young girl caught the virus from dead wild birds or animals near her home in the Prey Veng province in south Cambodia, close to the border with Vietnam — 22 chickens and three ducks were found dead nearby, per The Telegraph.

Officials have taken samples from those birds as well as at least 12 people who came into contact with the girl, according to Reuters. As of Friday, the girl's father had tested positive for the virus, but we don't know how he caught it.

Jonathan Ball, a professor of molecular virology at the University of Nottingham, UK, told the Science Media Centre on Friday that human infections are rare, and the likelihood of onward human to human transmission was "very low."

"There is always a risk of human infection, particularly in people in close contact with poultry or wild birds, and this risk increases during times where circulation of avian influenza is particularly high, as it is now," he said.
Humans don't usually catch bird flu, but it can be deadly

H5N1 causes fever, cough, and then can rapidly progress to respiratory failure, acute respiratory distress syndrome — a life-threatening condition when fluid builds up in the tiny air sacs in the lungs — and multi-organ failure, according to the European Centre for Disease Control and Prevention. It states that 50% of people who catch it die, but that figure can vary between countries.

James Wood, head of the department of veterinary medicine at the University of Cambridge, UK, told the SMC that many people will have been exposed to H5N1 in recent years, but only a few had caught it.

"This one case in itself does not signal the global situation has suddenly changed," he said.

Ball said that the risk to humans is still "very low."

Experts, including Ball and Wood, told the SMC that H5N1 needs to be closely monitored, in part due to recent reports of it infecting mammals like sea lions in Peru.

"There are two ways H5N1 can change – the mutations it accumulates itself over a period of time, or the mutations it develops as it links with other species," David Heymann, an infectious disease epidemiologist at the London School of Hygiene and Tropical Medicine,UK, told The Telegraph.

But he cautioned that "no one can say the risk is low, high or intermediate," because a mutation or "spillover" from another species was an unpredictable, "chance event."

"By far the most likely scenario for H5N1 is that nothing happens right now," Francois Balloux, the director of the UCL Genetics Institute, UK, tweeted on Friday.

What is bird flu? 11-year-old girl in Cambodia dies from virus

Health agencies are modelling potential human-transmission scenarios for the H5N1 virus based on the Covid pandemic and the 1918 influenza outbreak

Harriet Sinclair
·Trending News Reporter
Fri, February 24, 2023 

Bird flu has spread rapidly across Europe in the most recent outbreak among poultry. (Reuters)

An 11-year-old girl has died from bird flu in Cambodia, after contracting the first known human case of the H5N1 virus in the country since 2014.

The girl became ill on 16 February and died on Wednesday, according to the country's health ministry. Her father has since been confirmed to have contracted the virus and 11 other people who came into contact with the child are being tested.

The case has put other countries on high alert for human cases of the virus, which has resulted in the deaths or culling of more than 200 million birds around the world.

Although the virus has spread rapidly among the UK's avian population, the UK Health Security Agency (UKHSA) has said there is "no evidence so far that the virus is getting better at infecting humans or other mammals".


Girl, 11, dies in Cambodia after catching bird flu, government says (The Independent, 2-min read)
What is bird flu?

Avian influenza, otherwise known as bird flu, is categorised as influenza A H5N1. The virus has spread widely in birds around the world since 2021 but has thus far resulted in very few infections in humans.

According to the European Centre of Disease Control the virus is a "highly pathogenic avian influenza virus", meaning it has a high mortality rate among infected poultry.

The 2021/2022 epidemic has been among the worst recorded in Europe, and the UKHSA is currently looking into potential response scenarios should the virus begin to transmit to humans more widely.

The agency is currently assessing whether the lateral flow devices used to detect COVID could be used to test for the H5N1 virus in humans, and has been monitoring people who have come into contact with infected birds.

Arturo Casadevall, the chair of the Department of Molecular Microbiology and Immunology at Johns Hopkins University in the US, which supplied widely used coronavirus tracking data, said information on whether the 12 suspected new infections in Cambodia would be key.



The UKHSA is currently modelling several different potential scenarios of human transmission - one based on the recent coronavirus pandemic, and one based on the 1918 flu outbreak, whose fatality rate was higher.

In a potential scenario with a higher fatality rate, people could see "significant behavioural differences relative to the recent pandemic experience", UKHSA said.

Dr Meera Chand, incident director for avian influenza at UKHSA, said: "The latest evidence suggests that the avian influenza viruses we’re seeing circulating in birds do not currently spread easily to people.

"However, viruses constantly evolve, and we remain vigilant for any evidence of changing risk to the population, as well as working with partners to address gaps in the scientific evidence."

Bird flu: Health officials draw up COVID-style model looking at pandemic possibilities (Sky News, 3-min read)

Bird flu situation 'worrying'; WHO working with Cambodia


Fri, February 24, 2023
By Jennifer Rigby

LONDON (Reuters) -The World Health Organization is working with Cambodian authorities after two confirmed human cases of H5N1 bird flu were found among one family in the country.

Describing the situation as "worrying" due to the recent rise in cases in birds and mammals, Dr Sylvie Briand, the director of epidemic and pandemic preparedness and prevention, told reporters in a virtual briefing that WHO was reviewing its global risk assessment in light of the recent developments.

The U.N. health agency last assessed the risk to humans from avian flu as low earlier this month.

Cambodian authorities on Thursday reported the death of an 11-year old girl due to H5N1, and began testing 12 of her contacts. Her father, who had been showing symptoms, has also tested positive for the virus.

"The global H5N1 situation is worrying given the wide spread of the virus in birds around the world and the increasing reports of cases in mammals including humans," Briand said. "WHO takes the risk from this virus seriously and urges heightened vigilance from all countries."

Briand said it was not yet clear whether there had been any human-to-human transmission, which was a key reason to focus on the cases in Cambodia, or if the two cases were due to the "same environmental conditions," likely close contact with infected birds or other animals.

A new strain of H5N1, clade 2.3.4.4b, emerged in 2020 and has been causing record numbers of deaths among wild birds and domestic poultry in recent months. It has also infected mammals, raising global concerns.

However, unlike earlier outbreaks of H5N1, which has been around for more than two decades, this subtype is not causing significant illness in people. So far, only about a half dozen cases have been reported to the WHO in people who had close contact with infected birds, and most of those have been mild. Experts have suggested that the virus might need to change in order for human transmission to occur.

However, WHO said it was stepping up preparedness efforts regardless, and noted that there were antivirals available, as well as 20 licensed pandemic vaccines if the situation changes, although they would have to be updated to more closely match the circulating strain of H5N1 if needed.

That could take four to five months, said Richard Webby, director of the WHO Collaborating Center for Studies on the Ecology of Influenza in Animals and Birds at St. Jude Children's Hospital. However, some stockpiled vaccines would be available in the meantime.

WHO-affiliated labs already hold two flu virus strains that are closely related to the circulating H5N1 virus, which manufacturers can use to develop new shots if needed. A global meeting of flu experts this week suggested developing another strain that more closely matches H5N1 clade 2.3.4.4b, Webby told the briefing.

(Reporting by Jennifer Rigby; editing by Jon Boyle, Jason Neely and Tomasz Janowski)

LA REVUE GAUCHE - Left Comment: Search results for BIRD FLU 

LA REVUE GAUCHE - Left Comment: Search results for H5N1 

 

High H5N1 influenza levels found in mice given raw milk from infected dairy cows

NIH/NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES

 

IMAGE: 

COLORIZED TRANSMISSION ELECTRON MICROGRAPH OF AVIAN INFLUENZA A H5N1 VIRUS PARTICLES (GOLD), GROWN IN MADIN-DARBY CANINE KIDNEY (MDCK) EPITHELIAL CELLS. MICROSCOPY BY CDC; REPOSITIONED AND RECOLORED BY NIAID.

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CREDIT: CDC AND NIAID

WHAT:
Mice administered raw milk samples from dairy cows infected with H5N1 influenza experienced high virus levels in their respiratory organs and lower virus levels in other vital organs, according to findings published in the New England Journal of Medicine. The results suggest that consumption of raw milk by animals poses a risk for H5N1 infection and raises questions about its potential risk in humans. 

Since 2003, H5N1 influenza viruses have circulated in 23 countries, primarily affecting wild birds and poultry with about 900 human cases, primarily among people who have had close contact with infected birds. In the past few years, however, a highly pathogenic avian influenza virus called HPAI H5N1 has spread to infect more than 50 animal species, and in late March, the United States reported a viral outbreak among dairy cows in Texas. To date, 52 cattle herds across nine states have been affected, with two human infections detected in farm workers with conjunctivitis. Although the virus has so far shown no genetic evidence of acquiring the ability to spread from person-to-person, public health officials are closely monitoring the dairy cow situation as part of overarching pandemic preparedness efforts. 

To assess the risk of H5N1 infection by consuming raw milk, researchers from the University of Wisconsin-Madison and Texas A&M Veterinary Medical Diagnostic Laboratory fed droplets of raw milk from infected dairy cattle to five mice. The animals demonstrated signs of illness, including lethargy, on day 1 and were euthanized on day 4 to determine organ virus levels. The researchers discovered high levels of virus in the animals’ nasal passages, trachea and lungs and moderate-to-low virus levels in other organs, consistent with H5N1 infections found in other mammals. 

In addition to the mice studies, the researchers also tested to determine which temperatures and time intervals inactivate H5N1 virus in raw milk from dairy cows. Four milk samples with confirmed high H5N1 levels were tested at 63 degrees Celsius (145.4 degrees Fahrenheit) for 5, 10, 20 and 30 minutes, or at 72 degrees Celsius (161.6 degrees Fahrenheit) for 5, 10, 15, 20 and/or 30 seconds. Each of the time intervals at 63℃ successfully killed the virus. At 72℃, virus levels were diminished but not completely inactivated after 15 and 20 seconds. The authors emphasize, however, that their laboratory study was not identical to large-scale industrial pasteurization of raw milk and reflect experimental conditions that should be replicated with direct measurement of infected milk in commercial pasteurization equipment. 

In a separate experiment, the researchers stored raw milk infected with H5N1 at 4℃ (39.2 degrees Fahrenheit) for five weeks and found only a small decline in virus levels, suggesting that the virus in raw milk may remain infectious when maintained at refrigerated temperatures.

To date, the U.S. Food and Drug Administration concludes that the totality of evidence continues to indicate that the commercial milk supply is safe.  While laboratory benchtop studies provide important, useful information, there are limitations that challenge inferences to real world commercial processing and pasteurization.  The FDA conducted an initial survey of 297 retail dairy products collected at retail locations in 17 states and represented products produced at 132 processing locations in 38 states.  All of the samples were found to be negative for viable virus.  These results underscore the opportunity to conduct additional studies that closely replicate real world conditions.  FDA, in partnership with USDA, is conducting pasteurization validation studies – including the use of a homogenizer and continuous flow pasteurizer.  Additional results will be made available as soon as they are available.

The National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, funded the work of the University of Wisconsin-Madison researchers. 

ARTICLE:
G Lizheng et al. Cow Milk Containing H5N1 Influenza Viruses—Heat Inactivation and Infectivity in Mice. The New England Journal of Medicine DOI: 10.1056/NEJMc2405495 (2024).

WHO:
NIAID Director Jeanne Marrazzo, M.D., and Lauren Byrd-Leotis, Ph.D., with NIAID’s Division of Microbiology and Infectious Diseases’ Viral Respiratory Diseases Section, are available to discuss the findings. 

CONTACT:
To schedule interviews, please contact Kathy Donbeck, (301) 402-1663, niaidnews@niaid.nih.gov.

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NIAID conducts and supports research—at NIH, throughout the United States, and worldwide—to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses. News releases, fact sheets and other NIAID-related materials are available on the NIAID website.

About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov/.

NIH...Turning Discovery Into Health®

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JOURNAL

New England Journal of Medicine

DOI

10.1056/NEJMc2405495 

Bird flu in Canada: What to know about poultry and milk safety

By Nicole Ireland

 The Canadian Press
Posted November 15, 2024 

WATCH: British Columbia’s health ministry says the first suspected human case of avian influenza has been detected in Canada.


People have been hearing a lot about H5N1 bird flu — or highly pathogenic avian influenza — since a B.C. teen became the first human to get the virus in Canada and is in hospital.

It’s not yet known how the teen got infected, but Dr. Theresa Tam, Canada’s chief public health officer, said on Wednesday that genomic sequencing shows they have a strain of H5N1 similar to the strains found in poultry farm outbreaks in British Columbia.

More than 20 locations with infected poultry have been identified in the province since the beginning of October, according to a news release posted recently on the B.C. government website.

The H5N1 strain the teen has is not the same genotype that’s been found in people who were infected by dairy cattle in the U.S., Tam said in an interview.

While there have been several outbreaks of bird flu on dairy farms in multiple states, the virus has not been detected on dairy farms anywhere in Canada.

3:37  H5N1 avian flu detected in teen




How do we know dairy cattle in Canada aren't infected with H5N1?

The Canadian Food Inspection Agency has been testing raw milk arriving at processing plants in each province for the bird flu virus.

It has also been testing pasteurized retail milk samples.

Tam said that like wastewater testing for viruses such as COVID-19 and seasonal flu, the milk testing aims to provide an “early warning” signal if H5N1 has reached dairy farms in Canada.

If H5N1 ends up in milk, is it still safe to drink?

Yes, as long as milk has been pasteurized, the Canadian Food Inspection Agency says.

“In Canada, milk must be pasteurized before sale. The pasteurization process kills harmful bacteria and viruses, including HPAI (highly pathogenic avian influenza), ensuring milk and milk products are safe to drink and eat,” the CFIA website says.

Is it safe to eat poultry, eggs and beef?

Yes, as long as they are cooked thoroughly.

Where are the infected poultry farms in Canada?

As of Nov. 13, there were 28 infected poultry locations in British Columbia, two in Alberta and one in Saskatchewan, according to the Canadian Food Inspection Agency’s website.

Shayan Sharif, a pathobiology professor at the Ontario Veterinary College at the University of Guelph, said he believes H5N1 will reach poultry farms in other provinces.

“I hope to be proven wrong … but I think it’s probably going to come eastward in the not too distant future,” he told The Canadian Press.

1:53 What risk do zoonotic diseases pose?

What do you do when there is an H5N1 infection on a farm?

Farmers are required to notify the CFIA if they suspect their birds or livestock have avian flu

All poultry must be killed on farms that have tested positive for H5N1, said Sharif. But cattle don’t have to be killed, he said.

The virus can be spread through direct contact with infected animals, but can also spread through contaminated barns and other environments.

“Biosecurity” is one of the most important ways to stop the spread of avian flu between farms, Sharif said.

That means workers should wear personal protective equipment and change clothing when they enter and exit a farm where avian flu has been detected.

2:16  WHO says Bird flu risk to humans an ‘enormous concern,’ but what should you know?

It also means not sharing equipment between farms, as well as washing and disinfecting trucks delivering supplies and feed, he said.

Sharif said he supports offering avian flu vaccines to farm workers — a move that Finland has adopted.

Health Canada has authorized three influenza vaccines that could be used to protect against H5N1 avian flu.

Those vaccines are not currently available here, but Tam said public health officials are “very interested” in learning from Finland and are actively looking into the potential use of H5N1 vaccines as they monitor avian flu activity in Canada.

CDC Prepping for 'Possibility of Increased Risk to Human Health' From Bird Flu

— Approximately 350 recently exposed farm workers are being monitored

by Katherine Kahn , Staff Writer, MedPage TodayMay 24, 2024

The CDC is preparing for the possibility of H5N1 posing an increased risk to human health, even though that current risk remains low, the agency said on Friday.

"It is possible that influenza A(H5N1) viruses could change in ways that allow them to easily infect people and to efficiently spread between people, potentially causing a pandemic," the agency stated in an email to media.

As of May 22, about 350 farm workers are being monitored for illness after exposure to infected cows or infected raw cow's milk, according to researchers led by Shikha Garg, MD, of the CDC's National Center for Immunization and Respiratory Diseases, writing in the Morbidity and Mortality Weekly Reportopens in a new tab or window.

"The number of persons monitored continues to increase," they added.

In April, the CDC announced that a dairy farm workeropens in a new tab or window in Texas developed conjunctivitis associated with H5N1 infection, the first human case linked to an ongoing multistate outbreak in dairy cows. Then earlier this week, a second caseopens in a new tab or window in Michigan was reported of a person who also developed conjunctivitis from infection with H5N1. This most recent case was identified through daily monitoring of farm workers, the report said.

Of note, a study published on Fridayopens in a new tab or window in the New England Journal of Medicine showed that when researchers fed mice raw milk from dairy cows infected with H5N1, the mice rapidly developed signs of illness. At 4 days after exposure, high levels of virus were found in the animals' nasal passages, trachea, and lungs and moderate-to-low virus levels were identified in other organs, a finding that is consistent with H5N1 infections found in other mammalsopens in a new tab or window.

The FDA has confirmed that pasteurization inactivates H5N1 virusesopens in a new tab or window and that the commercial milk supply is safe, however "all persons should avoid consuming raw milk or products produced from raw milk," noted Garg and colleagues.

Clinicians should consider the possibility of H5N1 when evaluating patients who present with conjunctivitis or respiratory illness following a relevant exposure, the CDC authors emphasized. People who have job-related or recreational exposure to infected birds, poultry, dairy cattle, or other infected animals or contaminated materials are at highest risk for infection and should take precautions, including using personal protective equipment, self-monitoring for symptoms of illness, and seeking prompt medical care if they develop symptoms.

While reiterating that the current risk to the U.S. public from H5N1 viruses is low, if a novel influenza A virus acquired the ability to infect and be transmitted easily in humans in a sustained manner, "an influenza pandemic could occur," the CDC authors wrote.

"Comprehensive worldwide surveillance and investigation of every novel influenza A virus case in humans is essential to prepare for any developments that increase the risk to human health," Garg and coauthors emphasized.

The CDC is currently monitoring trends in influenza activity by looking for unusual changes in the percentage of positive influenza tests and through the CDC's National Wastewater Surveillance System. As of May 18, no indicators of H5N1 or other unusual human influenza activity has been detected.

The CDC is also increasing influenza surveillance activitiesopens in a new tab or window over the coming months by working with commercial laboratories to increase submission of influenza-positive test specimens to public health laboratories for virus subtyping. Also, the CDC is collaborating with manufacturers of commercial diagnostic tests to potentially develop an H5N1 test that could be made widely available if needed.

• 

  Katherine Kahn is a staff writer at MedPage Today, covering the infectious diseases beat. She has been a medical writer for over 15 years.

H5N1 ZOONOSIS

Bird flu pandemic in future? EU warns of potential spread to humans due to 'lack of immune defense’

Alert follows confirmation of rare human case in Texas

 By Melissa Rudy Fox News
Published April 3, 2024 

As avian influenza (bird flu) continues to spread among wild birds in the European Union, officials are warning of the potential for a future human pandemic.

On Wednesday, the European Food Safety Authority (EFSA) issued an alert noting that "transmission between bird and mammal species has been observed, particularly in fur animal farms, where outbreaks have been reported."

Although it is rare for infected birds to pass along the virus to humans, the agency warned that new strains could pose a danger in the future.

"These viruses continue to evolve globally, and with the migration of wild birds, new strains carrying potential mutations for mammalian adaptation could be selected," the alert stated.

"If avian A (H5N1) influenza viruses acquire the ability to spread efficiently among humans, large‐scale transmission could occur due to the lack of immune defenses against H5 viruses in humans."



As avian influenza (bird flu) continues to spread among wild birds in the European Union, officials are warning of the potential for a future human pandemic. (iStock)

In other words, humans don’t have immunity against bird flu — which means it could potentially spread quickly.

The flu has been found to spread between birds and mammals, the EFSA noted — "particularly in fur animal farms, where outbreaks have been reported."

To prevent the risk of a bird flu pandemic, the agency recommended taking steps to limit exposure and prevent the spread to mammals and humans.

"Key options for actions include enhancing surveillance targeting humans and animals, ensuring access to rapid diagnostics, promoting collaboration between animal and human sectors, and implementing preventive measures such as vaccination," the EFSA wrote.



"People with close or prolonged, unprotected exposures to infected birds or other animals (including livestock), or to environments contaminated by infected birds or other animals, are at greater risk of infection," the U.S. Centers for Disease Control and Prevention said. (iStock)

"Effective communication to different involved target audiences should be emphasized, as well as strengthening veterinary infrastructure, enforcing biosecurity measures at farms, and reducing wildlife contact with domestic animals."

The agency also called for "careful planning of poultry and fur animal farming," particularly in locations with large numbers of waterfowl (aquatic birds like ducks and geese).
Human cases in the U.S.

On Monday, the U.S. Centers for Disease Control and Prevention (CDC) announced that a person in Texas tested positive for H5N1 bird flu.

"This person had exposure to dairy cattle in Texas presumed to be infected with HPAI A(H5N1) viruses," the CDC’s statement said.

"The patient reported eye redness (consistent with conjunctivitis), as their only symptom, and is recovering. The patient was told to isolate and is being treated with an antiviral drug for flu."


The CDC said this is the second case of a human testing positive for H5N1 in the U.S., after a previous case was observed in Colorado in 2022.



"If avian A (H5N1) influenza viruses acquire the ability to spread efficiently among humans, large‐scale transmission could occur due to the lack of immune defenses against H5 viruses in humans," the European Food Safety Authority said. (iStock)

"This infection does not change the H5N1 bird flu human health risk assessment for the U.S. general public, which CDC considers to be low," it added.

"However, people with close or prolonged, unprotected exposures to infected birds or other animals (including livestock), or to environments contaminated by infected birds or other animals, are at greater risk of infection."


"At present, it does not transmit readily from person to person."

The CDC said it is "working with state health departments to continue to monitor workers who may have been in contact with infected or potentially infected birds/animals and test those people who develop symptoms."

Human symptoms can range from mild (e.g., eye infection, upper respiratory symptoms) to severe illness (e.g., pneumonia), according to the CDC.
Infectious diseases expert weighs in

Erica Susky, a Toronto-based medical microbiologist certified in infection control, said she believes there is generally "not a high risk" of human-to-human transmission, given that "the natural reservoir" of H5N1 and other strains of avian influenza is birds and not humans.

"Cases of H5N1 in humans usually occur in people who have had contact with birds (slaughter, de-feathering, butchering or preparing)," she told Fox News Digital.



The EU agency called for "careful planning of poultry and fur animal farming," particularly in locations with large numbers of waterfowl. (iStock)


While bird flu has a 60% fatality in humans, Susky noted, it rarely occurs.

"At present, it does not transmit readily from person to person," she said.

The primary concern involves the influenza virus, she said, which is "excellent at mutating and recombining."

"If there are repeated contacts between species that are the natural reservoir for one type of influenza viral strain — like birds and H5N1 — and humans, the chances of this novel strain adapting to spread in this different species increases," Susky told Fox News Digital.

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"As there are more cases of H5N1, there are more chances for a crossover event into humans."

Some of the biggest sources of spread, Susky said, are industrial agriculture and modern cities, where a virus like influenza can pass readily through human and bird populations.


"Currently, birds share influenza strains less often with humans, though that can change — it is how past influenza pandemics have arisen," she said.



The CDC on Monday announced that a person in Texas tested positive for H5N1 bird flu. (REUTERS/Dado Ruvic/Illustration/File Photo)

To prevent spread, Susky recommended practicing proper infection prevention techniques, which is important not only for bird flu, but also for seasonal influenza.

Those techniques include following proper and frequent hand hygiene before preparing food, eating or touching one’s face, and after using the washroom or coming in contact with animals.

Other mitigation strategies include receiving the annual influenza vaccine for those who qualify, and not going out among other people while feeling ill.

"The best way to minimize one’s risk of coming in contact with novel influenza strains is to avoid contact with birds and wild animals, if possible," Susky added.

Fox News Digital's Greg Norman contributed to this report.

 Michigan reports a human case of bird flu, the nation’s second linked to H5N1 outbreak in dairy cows

By Helen Branswell  and Megan Molteni May 22, 2024

Microscopic image of H5N1 avian influenza virus particles (in orange).CDC AND NIAID

Asecond human case of bird flu infection linked to the current H5N1 outbreak in dairy cows has been detected, in a farm worker who had exposure to infected cows, Michigan state health authorities announced on Wednesday.

In a statement, health officials said the individual had mild symptoms and has recovered. Evidence to date suggests this is a sporadic infection, with no signs of ongoing spread, the statement said.

“Farmworkers who have been exposed to impacted animals have been askd to report even mild symptoms, and testing for the virus has been made available,” Natasha Bagdasarian, the state’s chief medical executive, said in the statement.

“The current health risk to the general public remains low,” she added. “This virus is being closely monitored, and we have not seen signs of sustained human-to-human transmission at this point. This is exactly how public health is meant to work, in early detection and monitoring of new and emerging illnesses.”

This is only the third human case ever of H5N1 reported in the United States. A man in Texas who worked on a dairy farm was infected there earlier in this outbreak. The country’s first case, in the spring of 2022, was in a man in Colorado who was involved in culling H5N1-infected birds in a poultry outbreak there.

The Centers for Disease Control and Prevention said a nasal swab taken from the Michigan farm worker was negative for flu. But a swab of the person’s eye was sent to the CDC, where it tested positive for H5 flu virus, though final confirmation that it’s the H5N1 subtype is pending genetic sequencing. This was the only symptom the individual had, the CDC said.

In the Texas case in late March, the only symptom reported was conjunctivitis, also known as pink eye.

“We found this case because we were looking for this case. And we were looking for it because we were prepared. And in particular, the state of Michigan was prepared,” CDC’s Principal Deputy Director Nirav Shah said during a press conference organized by the U.S. Department of Health and Human Services.

Jennifer Nuzzo, director of the Pandemic Center at Brown University’s School of Public Health, said she wished other states were looking for H5N1 cases as aggressively as Michigan is.

“If there’s any takeaway from this finding it’s that this is probably the tip of the iceberg because this is the one state that we know of that has done the most in terms of testing on farms of both cows and also monitoring workers that are on the farms where they found cattle infections,” she told STAT.

Nuzzo said she took no comfort from the fact that only two human cases have been detected so far in this outbreak, and worries that people may be reading too much into that low number.

“The absence of finding cases is being interpreted as reassuring, that this [outbreak] is perhaps something that is abating,” she said. “And I have absolutely no ability to tell you that’s happening, in part because I think the testing that we’re doing could very well be qualitatively … misleading.”

During the press conference, Dawn O’Connell, assistant secretary for preparedness and response at HHS, revealed that 4.8 million doses of H5N1 vaccine that has been stockpiled in bulk is in the process of being put into vials — a process called fill and finish. This is a little less than half of the vaccine believed to be effective against the current strain of H5N1 that is stored in the National Pre-Pandemic Influenza Vaccine Stockpile.

O’Connell said the decision to make the vaccine more readily deployable was taken a couple of weeks ago. “It takes a couple of months to be able to fill and finish vaccine doses… so I thought it made sense, given what we were seeing,” she said.

O’Connell said a decision to use the vaccine has not been made.

To date, nearly 900 people in 24 countries have been confirmed to have been infected with H5N1 since 2003, with most cases tied to exposure to infected poultry. On rare occasions, there have been small clusters of cases that raised questions about whether limited person-to-person spread has occurred — something that is hard to prove when multiple people have the same exposures to infected animals. Ongoing spread among people has not been detected, and it is believed the virus would need to evolve further to gain the ability to spread easily to and among people.

The outbreak in cattle, the first known to have occurred with this virus, was confirmed in late March, though evidence suggests that it had been underway for several months before testing revealed the cause of a drop in milk production among cows.

Since then the U.S. Department of Agriculture has confirmed outbreaks in 52 herds in nine states, including Michigan, which has reported 19 infected herds — more than any other state. (The USDA’s most recent tally does not include four that Michigan reported since May 17.)

Experts following the outbreak believe the national count of affected herds significantly underestimates the scope of the problem. Both the USDA and the CDC have admitted that farmers have been reluctant to allow testing of their cows or their workers, afraid of the stigma attached to being associated with the outbreak.

But that has been less true in Michigan, where state officials have taken a uniquely aggressive stance in its public health response, informed, in part, by the devastating impacts H5N1 has had on the state’s poultry flocks in the past few years.

On May 1, Tim Boring, director of the state’s Department of Agriculture, declared an “extraordinary animal health emergency,” signing an order requiring Michigan farmers to step up their biosecurity measures. “Most farms have been good cooperators with that,” Boring told STAT in an interview last week.

Related: When should we start making H5N1 vaccine, and who will make that decision? In short, it’s complicated

Farmers have also been open to working with local health authorities to fill out questionnaires that could help investigators track how the virus is moving between dairy herds throughout the state. “Hundreds and hundreds of farm workers here in Michigan have been interviewed,” Boring said. “They understand the importance of understanding how this is moving around so we can limit the spread of this.”

Local health authorities have also been monitoring workers from farms with infected herds for symptoms — either through regular phone calls with farm supervisors or automated text messages that ask if they’ve been experiencing conjunctivitis or any flu-like symptoms, even mild ones. Testing is being offered to any symptomatic workers who’ve been exposed to animals on affected farms or are living in congregate settings with people who’ve been exposed.

In an interview Wednesday afternoon, Bagdasarian, the Michigan health official, described the discovery of a human case as a sign these efforts to find new infections are paying off. “Michigan has really been one of the states leading in terms of testing, so it’s not surprising that we have picked up on this sporadic case,” she said. At least 35 people have been tested so far, she said. This case is the first to have come back positive.

Bagdasarian said officials have seen no evidence of secondary infections. But the state is not yet conducting serological surveys — looking for antibodies to H5N1 in the blood of farm workers and those they’ve been in contact with — to determine if there have been unreported cases, and possibly even spread from those individuals to others.

“We’ve always talked about the need to do additional studies to do additional engagement, and to do a big look at serology, especially for people who may have remained asymptomatic throughout,” Bagdasarian said. “That would be a next step.”

Shah said the CDC would very much like to conduct serology studies among dairy farm workers, including those, like the Michigan individual, who test positive. “At this time, we’re not there yet,” he said.

Eric Deeble, the USDA’s acting senior advisor for H5N1, announced during the news conference that additional financial incentives are being planned to try to entice dairy farmers to report infections in their herds and take steps to reduce the risks to cows and workers on the farms. Compensation for lost milk — a substantial drop in milk production is the most notable sign of infection in a herd — is planned, but will take a few more weeks to finalize, he said.

This story has been updated throughout with comments from the HHS news conference and interviews with Bagdasarian and Nuzzo.

About the Author

Helen Branswell

Senior Writer, Infectious Diseases

Helen Branswell covers issues broadly related to infectious diseases, including outbreaks, 

preparedness, research, and vaccine development. Follow her on Mastodon and Bluesky.

 @HelenBranswell

 linkedin.com/in/helen-branswell-22ab936/

Megan Molteni

Science Writer

Megan Molteni reports on discoveries from the frontiers of genomic medicine, neuroscience,

 and reproductive tech. She joined STAT in 2021 after covering health and science at WIRED.

 megan.molteni@statnews.com

 @MeganMolteni

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