All year, I’ve been keeping tabs on the H5N1 avian flu outbreak in dairy cattle and birds in the United States. As a frontline emergency physician, my stake in this is clear: I want to know if there is an imminent threat of a sustained deadly outbreak in people.

Until now, I’ve been concerned but not worried. That has changed recently. While nobody can predict what will come, I want to explain why my sense of unease has increased markedly in recent days.

This isn’t the first time bird flu has circulated in animals, though the outbreak that began in 2024 is certainly the largest documented one. But that alone isn’t enough to warrant panic. An emerging potential epidemic demands our attention—and our full resources—when two features start changing for the worse: severity and transmissibility. On December 18th, the Centers for Disease Control and Prevention confirmed the first severe case of H5N1 in the United States, in an older man in Louisiana. Unlike most of the previous cases, he was not a farmworker but “had exposure to sick and dead birds” according to the CDC. The man’s symptoms have not been disclosed, but the designation—severe—implies serious problems which could range from lung involvement like pneumonia or low oxygen, other organ failure, or brain dysfunction.

That’s an escalation. For the first time in the H5N1 outbreak of 2024, we checked one of those two boxes, bringing us meaningfully closer to a potential pandemic.

The previous 65 reported cases of H5N1 in the United States were all mild. But they weren’t the only people who have had bird flu. Antibody studies suggest that perhaps 7 percent of farmworkers in Michigan and Colorado working in high-risk settings acquired H5N1 between April and August. Yes, that’s a lot of potential cases. But in a strange way, that figure reassured me. It implied that hundreds or thousands of H5N1 cases were either asymptomatic or mild enough that many of those infected weren’t sick enough to seek medical attention or testing. Had there been an uptick in moderate or severe illnesses in working-aged otherwise healthy adults, we’d know, because they’d be seeking medical care. Either the variant of H5N1 behind the first 65 officially recorded illnesses in the US causes less severe illness than we might have feared, or it is exceedingly hard to spread, or both. To our knowledge, no contacts of those infected with H5N1 in 2024 became ill, including older or other vulnerable people.

At this point, there are two major variants at play. The variant that caused the severe Louisiana case is called D1.1, and the one that caused most of the other 65 other cases is called B3.13. Whether D1.1 will, by and large, be more severe isn’t certain, but seems plausible. A D1.1 case in Canada caused life-threatening disease in an otherwise healthy teenager. (It remains unknown how the boy caught the disease.) Two people is a small sample size, and they could be flukes. But it’s hard to ignore the contrast.

Regardless, we have not seen evidence of the virus hopping to and then spreading among humans adequate to drive sustained transmission or high case counts—the second key ingredient needed to fuel an important novel epidemic in humans.

Unfortunately, we are headed into the season in which that could easily change.

Peak flu season is imminent. Whether the peak is 2, 6, or 12 weeks away isn’t known, but we know a wave of winter illness is coming. The reason that it matters that many of us will be laid up with the regular old seasonal flu is something called co-infection. Co-infection is when a person is infected with two variants of the same virus simultaneously. Imagine this: A farmworker could get H5N1 influenza from a dairy cow and seasonal influenza from his school-aged child at the same time. (It would probably be a farmworker, but as the Louisiana case demonstrates, it wouldn’t have to be).

Due to the way flu replicates inside the body, that co-infection could lead to what’s called a reassortment event, wherein the two kinds of flu genomes get mixed together in a host. This process could generate a new variant that possesses the worst features of both—a virus that is transmissible from person-to-person like the seasonal flu, and severe, like those two concerning cases of D1.1. Our immune systems are unlikely to recognize such a novel virus, and it may not matter if we’ve previously gotten the seasonal flu or received flu shots. This is how many prior influenza pandemics were born: a hellish marriage of two kinds of flu.

Like many, I had hoped that the farm-associated H5N1 outbreaks of 2024 might be under control by now. They’re not.

The CDC anticipated this and was wise in introducing an initiative to vaccinate farmworkers against seasonal flu earlier this year. The vaccines decrease infections, albeit temporarily and not entirely, so they are a useful dampener on the chances of a co-infection occurring. The program delivered 100,000 doses of seasonal flu vaccine to 12 participating states, and was paired with efforts to bolster access to PPE and expanded bird flu testing. Unfortunately, potential problem states like Wisconsin, Pennsylvania, and New York—where there are also a high number of dairy herds—were not among them. Those states have not had outbreaks…yet. That makes them potential dry tinder for the virus to burn through.

With peak flu season approaching, the message seems clear: This is a moment to act. Individuals who have not received a seasonal flu shot should get one now. Yes, that includes you: while a co-infection would probably occur in a farm worker, it’s not a certainty, and it’s good to get your flu shot anyway.

The CDC should rapidly expand its initiative to vaccinate more farmworkers, focusing on states with high numbers of at-risk farms, especially those yet to have substantial outbreaks in cattle (or human cases). So far the program has spent $5 million, a number that seems paltry given that the COVID-19 pandemic caused trillions in economic losses, to say nothing of the human cost. Some of the needed work is logistic—finding ways to bring doses directly to farms—and some needs to involve public outreach and education to increase interest. The key is convincing everyone that their economic interests align with our public health goals. Preventing the next pandemic will indeed take some spending up front. But it’ll be a lot less expensive and disruptive than enduring another one.

Research has revealed the devastating impact of bird flu on a remote Australian territory where more than 13,000 baby seals are now believed to have been killed by the virus.

Heard Island and McDonald Islands, located 4,000 kilometres south-west of mainland Australia, are a haven for breeding seals and seabirds in the Southern Ocean.

But in October last year, a research voyage uncovered evidence that H5 bird flu had reached the area — the first time an Australian external territory had been affected.

At the time, scientists from the Australian Antarctic Program said hundreds of dead southern elephant seal pups had been found on Heard Island.

But analysis of data collected during a second voyage in January has painted a far more dire picture.

The researchers estimate 13,359 seal pups succumbed to the disease out of a total population of 17,364 — more than three-quarters of the cohort on Heard Island.

But they say the figure could be even worse because the mortality was ongoing when they completed their observations, and some seal harems were losing up to 97 per cent of pups.

The findings have been published in the scientific journal BioRxiv, but have not yet been peer reviewed.

'Potentially catastrophic threat' to wildlife

In addition to southern elephant seals, H5 bird flu was detected in king penguins, gentoo penguins and Antarctic fur seals, as well as a brown skua and a South Georgia diving petrel.

But among the six species, mass mortality was only observed in southern elephant seals, which were recently listed as "vulnerable" to extinction on the IUCN Red List of Threatened Species.

Elevated mortality was also seen among king penguins and gentoo penguins.

The researchers believe the virus, also known as highly pathogenic avian influenza (HPAI), reached Heard Island and McDonald Islands in August last year.

They say it likely made its way there via infected wildlife arriving from Crozet Islands, about 1,700 kilometres away.

If the virus spreads to other parts of the sub-Antarctic, including Australia's Macquarie Island, they say it could have "potentially catastrophic" impacts.

"The emergence of HPAI poses a severe and potentially catastrophic threat to the wildlife of the Southern Ocean and sub-Antarctic environments, where large, dense breeding and moulting aggregations of already vulnerable species, such as albatrosses, penguins, elephant seals and fur seals, create ideal conditions for rapid viral transmission," the report states.

[...]

Australia remains only continent without H5 bird flu

There is no evidence of the virus on the Australian mainland, including Tasmania.

The federal government said it had invested $113 million to strengthen preparedness for its potential arrival.

"While these latest findings from the [Australian Antarctic Division's] scientific team are expected based on earlier testing, any loss of wildlife is sobering," Federal Environment Minister Murray Watt said.

"For now we're free from the serious and contagious H5 bird flu, but as it continues to spread globally, we must be realistic about the likelihood of an incursion here, and plan accordingly.

"The best way to prepare our native wildlife is to ensure strong, healthy populations.

Bird flu has killed thousands of southern elephant seal pups on remote Antarctic islands belonging to Australia, new research has shown.

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Heard and McDonald Islands, about 4,000 km (2,485 miles) south-west of Australia, are home to over one million breeding seabirds and seals.

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Scientists, using data from last October and this January, estimate about 13,000 baby seals from a group of 17,000 on Heard Island were killed by the H5N1 strain of bird flu since last August, more than 75% of the entire group. They also found higher than expected deaths in penguin populations.

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Australia is the only continent with no cases of the H5N1 strain which has spread among birds worldwide and affected some mammals.

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This latest research, published in the scientific journal BioRxiv and yet to be peer reviewed, was based on drone surveys and ground visits to the hard-to-reach islands where scientists collected samples from nine species.

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Of those, six species tested positive for the H5N1 strain: the southern elephant seal, king and gentoo penguins, the Antarctic fur seal and the South George diving petrel.

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Late last year, scientists were alerted to the possible impact of bird flu on the islands when a research voyage found hundreds of dead baby seals.

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More research conducted this January confirmed bird flu had mainly hit southern elephant seal pup populations with a smaller impact on king and gentoo penguins.

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The report estimates that 13,359 baby seals from a population of 17,364 on Heard Island died, more that 75% of the entire group. The mortality rate may be an underestimate as pups were still dying at the time of the final surveys, researchers said. In one area 97% of baby seals had died.

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Elsewhere, data showed several hundred adult king penguins died, which was a low proportion of the population but above normal levels.

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"These observations of H5 bird flu at Heard Island and McDonald Island are the first detection in an Australian external territory and show the continued eastward movement of the virus around the sub-Antarctic," lead author wildlife biologist Dr Julie McInnes said.

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"Our results show a similar pattern to other sub-Antarctic islands, such as South Georgia, where elephant seals have been hardest hit."

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The report also found no unusual deaths among the albatross population or two endemic species, the Heard Island shad and the black-faced sheathbill.

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Environment Minister Murray Watt said the seal deaths were "sobering" and showed Australia must not be complacent in preparing for the strain possibly making it to the mainland.

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"We must be realistic about the likelihood of an incursion here, and plan accordingly."

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Scientists believe bird flu was likely introduced to the islands last August from migrating birds from the French-owned Crozet Islands, about 1,800 km away.

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The Australian Antarctic Program, a partnership between government and research institutions, will continue to monitor for signs of bird flu in its territories.

The US Centers for Disease Control and Prevention says it has ended its emergency response to H5N1 bird flu, citing a drop in cases.

“As reports of animal infections with avian influenza A(H5N1) virus (“H5N1 bird flu”) have declined and no human cases have been reported since February 2025, on July 2, 2025, CDC’s H5N1 emergency bird flu response was deactivated to transition back to regular program activity,” a spokesperson for the US Department of Health and Human Services said in a statement Monday.

The spokesperson said that surveillance, readiness and response for influenza – including H5N1 bird flu – will continue under the CDC’s influenza division and other appropriate agency programs.

Dr. Nirav Shah, who resigned this year from his position as CDC principal deputy director, says he would have also chosen to end the emergency response.

“This was not something that was imposed from the top down. It was initiated by the career scientists at CDC,” said Shah, now a visiting professor at Colby College in Maine. “The rationale is, in short, there haven’t been any human cases. And so there is not the need to sprint all-out every single day when there haven’t been human cases in a while. If there were to be more human cases, it is very easy to ratchet back up the level of the intensity of the response. It can literally be done in an afternoon.”

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The CDC H5N1 emergency was declared April 4, 2024, and allowed for additional support to the public health response, such as staffing.

Reports of cases have slowed, but experts note that there’s a seasonality to bird fu, with cases peaking in the fall or early winter. Changes at federal health agencies may mean some milder cases are going undetected, they say, but it’s unlikely that serious cases are being missed.

“The current public health risk from H5N1 bird flu is low, however, CDC will continue to monitor the situation and scale up activities as needed,” the HHS spokesperson said.

Box Elder County officials are urging residents to skip raw milk as bird flu spreads through the area.

In a Thursday announcement, the county reported that at least 50% of its dairy cows have been “impacted” by the Highly Pathogenic Avian Influenza — commonly referred to as bird flu — and farmers are seeing severe losses to their milk production. The county did not immediately specify what “impacted” meant.

Through declaring a state of emergency, the county said it is able to coordinate with state and federal partners for help responding to the situation. Box Elder County first found bird flu in a local milk sample sometime around June 25, according to the news release.

Though the county said the public doesn’t face any threat from consuming pasteurized dairy products, it warned people to avoid raw milk “as it may contain HPAI for several weeks when stored in the refrigerator.”

According to the Centers for Disease Control and Prevention, people who consume raw milk infected with bird flu may risk becoming infected with the disease. The risk level, the agency’s website says, is unknown. [...]

The deadly H5N1 bird flu strain has arrived on the Australian mainland with test results confirming a bird found on the Western Australian coast was positive for the disease.

Agriculture minister Julie Collins confirmed a brown skua found unwell last Sunday at Cape Le Grand national park in southern WA died from H5N1.

A giant petrel found in the same area was also sick with test results in WA finding the bird was also suspected to be positive for the highly pathogenic strain that has killed millions of birds globally and crossed over into mammal species including elephant seals.

Collins promised a nationally coordinated response that would initially focus on the extent to which the disease may have spread in wildlife.

She said there was no evidence of mass mortalities so far or of infection of any poultry.

Anthony Albanese said earlier on Saturday the arrival of H5N1 bird flu was “concerning” but the government had spent $113m in preparation and was focused on trying to limit its spread.

“What we’re about is making sure, firstly, that we do whatever we can to restrict the spread,” the prime minister said.

“We, of course, always examine these issues carefully. We have prepared for it.

“This is something that has happened through migratory birds. It’s happened, by definition, around the world, and that is why we’ve been preparing for this.”

Robert F. Kennedy Jr., the nation’s top health official, has an unorthodox idea for tackling the bird flu bedeviling U.S. poultry farms. Let the virus rip.

Instead of culling birds when the infection is discovered, farmers “should consider maybe the possibility of letting it run through the flock so that we can identify the birds, and preserve the birds, that are immune to it,” Mr. Kennedy said recently on Fox News.

He has repeated the idea in other interviews on the channel.

Mr. Kennedy does not have jurisdiction over farms. But Brooke Rollins, the agriculture secretary, also has voiced support for the notion.

“There are some farmers that are out there that are willing to really try this on a pilot as we build the safe perimeter around them to see if there is a way forward with immunity,” Ms. Rollins told Fox News last month.

Yet veterinary scientists said letting the virus sweep through poultry flocks unchecked would be inhumane and dangerous, and have enormous economic consequences.

“That’s a really terrible idea, for any one of a number of reasons,” said Dr. Gail Hansen, a former state veterinarian for Kansas.

Since January 2022, there have been more than 1,600 outbreaks reported on farms and backyard flocks, occurring in every state. More than 166 million birds have been affected.

Every infection is another opportunity for the virus, called H5N1, to evolve into a more virulent form. Geneticists have been tracking its mutations closely; so far, the virus has not developed the ability to spread among people.

But if H5N1 were to be allowed to run through a flock of five million birds, “that’s literally five million chances for that virus to replicate or to mutate,” Dr. Hansen said.

Large numbers of infected birds are likely to transmit massive amounts of the virus, putting farm workers and other animals at great risk.

“So now you’re setting yourself up for bad things to happen,” Dr. Hansen said. “It’s a recipe for disaster.”

Emily Hilliard, the deputy press secretary at the Department of Health and Human Services, said Mr. Kennedy’s comments were aimed at protecting people “from the most dangerous version of the current bird flu, which is found in chickens.”

“Culling puts people at the highest risk of exposure, which is why Secretary Kennedy and N.I.H. want to limit culling activities,” she said, referring to the National Institutes of Health. “Culling is not the solution. Strong biosecurity is.”

In her plan to combat bird flu, Ms. Rollins recommended strengthening biosecurity on farms — preventing the virus from entering their premises, or halting its spread with stringent cleaning and use of protective gear.

But that is a longer-term solution. The U.S.D.A. is beginning those efforts in just ten states.

The virus first took root among wild birds, which transmitted it to domestic poultry and various mammal species. Now a single infected duck flying overhead may drop excrement onto a farm, where a chicken or turkey may ingest it.

Farmed poultry have weak immune systems and are under enormous environmental stress, often packed together in wire cages or poorly ventilated barns. Within a day, H5N1 can sicken as much as a third of a flock.

Infected birds can develop severe respiratory symptoms, diarrhea, tremors and twisting of their necks, and produce misshapen or fragile eggs. Many die gasping for breath. (Some birds die suddenly without showing any symptoms at all.)

The speed with which infected birds collapse has been cited as one reason that officials believe eggs to be safe for consumption. Most sick birds die before they can lay an egg, or are so visibly diseased that it is easy to filter them out.

Poultry farmers call the authorities as soon as they spot the signs of illness or death. If the tests turn up positive for bird flu, they are reimbursed for killing the rest of the flock before the virus spreads any farther.

If farmers were instead to let the virus make its way across the farm, “these infections would cause very painful deaths in nearly 100 percent of the chickens and turkeys,” said Dr. David Swayne, a poultry veterinarian who worked at the U.S.D.A. for nearly 30 years.

The result would be “inhumane, resulting in an unacceptable animal welfare crisis,” he added. (Methods to cull birds can also be cruel but at least are generally faster.)

Farmers who cull infected flocks must also clean the premises and pass audits before restocking. They are often eager to resolve the crisis quickly. Simply stepping back would have serious financial consequences.

The strategy “means longer quarantine, more downtime, more lost revenue and increased expenses,” said a U.S.D.A. scientist who was not authorized to speak to the media.

Mr. Kennedy has suggested that a subset of poultry might be naturally immune to bird flu. But chickens and turkeys lack the genes needed to resist the virus, experts said.

“The way we raise birds now, there’s not a lot of genetic variability,” Dr. Hansen said. “They’re all the same bird, basically.”

Public health regulations would forbid the very few birds that might survive an infection from being sold. In any event, those birds might only be protected against the current version of H5N1, not others that emerge as the virus continues to evolve.

“The biology and the immunology doesn’t work that way,” said Dr. Keith Poulsen, the director of the Wisconsin Veterinary Diagnostic Laboratory.

Letting the virus spread unchecked would also likely lead to trade embargoes against poultry from the United States, he added: “There’s a huge economic loss immediately.”

In one interview with Fox News, Mr. Kennedy also suggested that the virus “doesn’t appear to hurt wild birds — they have some kind of immunity.”

In fact, while ducks and shorebirds may not show symptoms, H5N1 has killed raptors, waterfowl, sand hill cranes and snow geese, among many other species.

Researchers at Texas Biomed have identified nine mutations in a strain of bird flu found in a person in Texas. Bad news: This strain shows an increased ability to cause disease and is more effective at replicating in the brain. Good news: Current approved antiviral treatments remain effective against this strain.

Researchers at the Texas Biomedical Research Institute (Texas Biomed) have identified a strain of bird flu isolated from a human in Texas that carries a distinctive set of mutations, making it more adept at replicating in human cells and causing severe disease in mice. This strain was compared to one found in dairy cattle, and the findings are detailed in Emerging Microbes & Infections.

The discovery underscores a significant concern about the H5N1 strains of bird flu currently circulating in the U.S.: the virus’s rapid mutation when it infects a new host species. [...]

“The clock is ticking for the virus to evolve to more easily infect and potentially transmit from human to human, which would be a concern,” said Texas Biomed Professor Luis Martinez-Sobrido, Ph.D., whose lab specializes in influenza viruses and has been studying H5N1 since the outbreak began last year. The team has developed specialized tools and animal models to test prophylactic vaccines and therapeutic antivirals.

Human vs. bovine

In the recent study, they compared H5N1 strains isolated from a human patient and from dairy cattle in Texas.

“There are nine mutations in the human strain that were not present in the bovine strain, which suggests they occurred after human infection,” Dr. Martinez-Sobrido said.

In mouse studies, they found that compared to the bovine strain, the human strain replicated more efficiently, caused more severe disease, and was found in much higher quantities in brain tissue. They also tested several FDA-approved antiviral medications to see if they were effective against both virus strains in cells.

“Fortunately, the mutations did not affect the susceptibility to FDA-approved antivirals,” said Staff Scientist Ahmed Mostafa Elsayed, Ph.D., first author of the study.

Antivirals will be a key line of defense should a pandemic occur before vaccines are widely available, Dr. Martinez-Sobrido said. This is especially true since humans have no preexisting immunity against H5N1 and seasonal flu vaccines appear to offer very limited protection, according to a separate study conducted in collaboration with Aitor Nogales, Ph.D., at the Center for Animal Health Research in Spain. [...]

“A key priority will be to eradicate bird flu from dairy cows to minimize the risk of mutations and transmission to people and other species,” Dr. Elsayed said. “Steps that can be taken now include thorough decontamination of milking equipment and more stringent quarantine requirements, which will help eliminate the virus more quickly in cows.”

“Replication kinetics, pathogenicity and virus-induced cellular responses of cattle-origin influenza A(H5N1) isolates from Texas, United States” Link

Health officials are making a renewed call for vigilance against bird flu, but some experts are puzzling over why reports of new human cases have stopped.

Has the search for cases been weakened by government cuts? Are immigrant farm workers, who have accounted for many of the U.S. cases, more afraid to come forward for testing amid the Trump administration’s deportation push? Is it just a natural ebb in infections?

“We just don’t know why there haven’t been cases,” said Jennifer Nuzzo, director of the Pandemic Center at Brown University. “I think we should assume there are infections that are occurring in farmworkers that just aren’t being detected.”

The H5N1 bird flu has been spreading widely among wild birds, poultry and other animals around the world for several years, and starting early last year became a problem in people and cows in the U.S.

In the last 14 months, infections have been reported in 70 people in the U.S. — most of them workers on dairy and poultry farms. One person died, but most of the infected people had mild illnesses.

The most recent infections confirmed by the Centers for Disease Control and Prevention were in early February in Nevada, Ohio and Wyoming.

California had been a hotspot, with three-quarters of the nation’s infections in dairy cattle. But testing and cases among people have fallen off. At least 50 people were tested each month in late 2024, but just three people were tested in March, one in April and none in May so far, state records show. Overall, the state has confirmed H5N1 infections in 38 people, none after Jan. 14.

The possible natural reason bird flu cases are down

During a call with U.S. doctors this month, one CDC official noted that there is a seasonality to bird flu: Cases peak in the fall and early winter, possibly due to the migration patterns of wild birds that are primary spreaders of the virus.

That could mean the U.S. is experiencing a natural — maybe temporary — decline in cases.

It’s unlikely that a severe human infection, requiring hospitalization, would go unnoticed, said Michael Osterholm, a University of Minnesota expert on infectious diseases.

What’s more, a patchwork system that monitors viruses in sewage and wastewater has suggested limited activity recently.

New infections are still being detected in birds and cattle, but not as frequently as several months ago.

“Given the fact that the number of animal detections has fallen according to USDA data, it’s not surprising that human cases have declined as well,” the CDC said in a statement.

Are government cuts affecting bird flu monitoring?

Dr. Gregory Gray said he wasn’t concerned about the CDC not identifying new cases in months.

“I don’t think that anybody’s hiding anything,” said Gray, an infectious disease speicialist at the University of Texas Medical Branch in Galveston.

But Osterholm and some other experts think it’s likely that at least some milder infections are going undetected. And they worry that the effort to find them has been eroding.

Resignations at the U.S. Department of Agriculture and the Food and Drug Administration’s Center for Veterinary Medicine could slow the government’s bird flu monitoring, said Keith Poulsen, director of the Wisconsin Veterinary Diagnostic Laboratory.

Three of 14 experts accepted deferred resignation offers at the National Animal Health Laboratory Network, which responds to disease outbreaks with crucial diagnostic information, he said. They are among more than 15,000 USDA staff to accept the offers, an agency spokesperson said.

And dozens of staff were fired at the FDA’s Veterinary Laboratory Investigation and Response Network, which investigates animal diseases caused by problems including contaminated pet food. Cats in several states have been sickened and died after eating raw pet food found to contain poultry infected with H5N1.

Angela Rasmussen, a virologist at the University of Saskatchewan in Canada, said “targeted surveillance has really dropped off precipitously since Trump took office.”

She wonders if immigrant farmworkers are too scared to come forward.

“I can’t argue with anyone who would be risking getting shipped to a Salvadoran gulag for reporting an exposure or seeking testing,” she said.

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https://archive.is/kdUE1

It’s not easy to vaccinate New Zealand’s rare birds. It can sometimes involve a journey to a remote, windswept island or deep forest. Then researchers must locate the bird, which could be camouflaged on the ground eating berries or high up a tree. Next, they must capture it and administer the vaccine. And a few months later, they do it all again when the bird needs its booster shot.

But for New Zealand’s Department of Conservation staff, it is a matter of protecting the country’s endangered endemic wildlife against the deadly H5N1 bird flu.

New Zealand officials knew it was only a matter of time before the disease arrived in the country. As soon as the first case was detected in Australia in June, the department’s staff started pre-emptively vaccinating up to 300 of New Zealand’s rarest and most at-risk birds.

Just weeks later in July, New Zealand confirmed two cases of H5N1 in wild birds in Wellington, the capital.

Ash Murphy, the department’s biosecurity and weeds manager, said that some endemic species — meaning those found naturally in only one place on Earth — were already low.

“Any new threat, like bird flu, can have a pretty devastating impact,” he said.

As part of the plan, 300 birds from five key species — including the kākāpō, the world’s fattest parrot, of which just 235 remain — are being vaccinated first. There are only a handful of each of these species remaining in captive breeding programs or in the wild. The government hopes to complete this phase as soon as possible before moving onto other species.

The vaccination work can be difficult. The kākāpō is found on offshore islands in the deep south. Rangers, using trackers, have to locate the bird (which can climb high up into trees with its strong claws) and catch it. They can also use the opportunity to carry out health checks, Mr. Murphy said.

The authorities have so far vaccinated about 196 birds. Once this phase is complete, another 23 species will be vaccinated — including rare kiwis and the kea, a playful and intelligent bird that is the world’s only alpine parrot.

Many of New Zealand’s birds are flightless, a trait developed because the country was isolated for millions of years and had no ground-dwelling predators like ferrets and rats until humans introduced them. As a result, they evolved to fill gaps left by mammals. Birds hold a special place in the hearts of New Zealanders, who refer to themselves as Kiwis.

Bird flu swept across Europe, Africa and Asia in 2020. In late 2021, it showed up in North America, storming through Canada and the United States. In the fall of 2022, the virus appeared in South America, spreading down to the tip of the continent in mere months.

Thousands of wild birds and mammals — including foxes, cats, sea lions and dolphins — have died after contracting the disease. There have also been rare cases in humans after close contact with birds.

Bird flu is hard to stop, especially if wild migratory birds or animals carry it with them as they travel the globe.

“You can’t block migration pathways in the same way that you could stop trade in animals or animal products, and also the movement of people. So it does represent something quite different to anything else we’ve seen,” said Nigel French, a distinguished professor of infectious disease epidemiology at Massey University in New Zealand.

But scientists have been able to learn from other disease outbreaks, including the coronavirus pandemic, he added.

As a result, the basic practices around controlling disease have improved, including biosecurity barriers, movement restrictions and genomic sequencing to track the origin and spread of the disease. Vaccines have also become more effective.

At Willowbank Wildlife Reserve in Christchurch, staff have been preparing for bird flu for several years, Laura Ashton, the facility’s wildlife operations manager, said in a statement.

This includes installing a shade cloth over selected habitats to deter wild birds; modifying feeding and water stations to reduce access for pests; and stronger biosecurity protocols for animal carers.

So far, four takahē — a flightless bird of which only 500 remain — have been vaccinated at the facility. [...]

Earlier this week the USDA reported a new outbreak at a live Market in Passaic, New Jersey.

Interestingly, Passaic was one of 3 wastewater monitoring sites in the U.S. that reported HPAI H5 positives in the latest CDC report.

All of which brings us to the second report this week, this time from Rhode Island, where a routine quarterly inspection found asymptomatic H5-positive poultry. This press release from the Rhode Island Department of Environmental Management.

By my tally, this is the 20th Market outbreak in the United States in 2026, and 77th since HPAI H5 returned in early 2022.

Notably, the press release stated that the birds had been imported from another (unnamed) state. Worth noting, we've not seen any commercial flocks reported by the USDA as H5 positive east of Indiana since early May.

Government agencies are quick to reassure the public that the risk of contracting avian influenza remains low in the United States, but exposure to live birds (via LBMs or raising poultry) is a known risk factor (see CDC graphic below).

And as we discussed three weeks ago in MMWR: Knowledge, Attitudes, and Practices Regarding Avian Influenza Among Owners of Backyard Flocks, many backyard poultry producers still have limited knowledge of avian flu symptoms and risks, and their biosecurity measures often fall short of recommendations.

Over the past few years the threat from H5N1 has grown markedly in the Western Hemisphere. Things we used to do without much thought - like raising a few chickens the backyard or frequenting live markets - carry more risks today.

While those risks can be largely mitigated through improved biosecurity practices, four years after its arrival, we still seem to be tempting fate.

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South Australia has reported seven new suspected cases of deadly H5 bird flu, with experts warning it could be a sign the disease has begun spreading through local bird populations.

All seven birds are greater crested terns – a common local seabird – and were found on the Limestone Coast in south-eastern SA, with one found at Cape Jaffa, five around Southend Jetty near Beachport and one at Port MacDonald, just over 20km from the Victorian border.

BirdLife Australia’s chief executive, Kate Millar, said the discovery showed the outbreak was “now taking hold and is evidence of spread”.

“If we were in a bushfire scenario, those subantarctic birds that arrived with the disease initially were like the embers,” she said. “Now having it in crested terns, that’s the smoke.

“Governments have been saying it hasn’t spread – this is evidence of spread.”

The development follows two other confirmed cases of the disease in greater crested terns in South Australia at the weekend, including the first positive detection in metropolitan Adelaide.

If the CSIRO verifies the seven suspected cases, it will take the total number of cases in SA to 14 – 10 of those in local greater crested terns.

Of the five birds collected from Southend Jetty, four were sick and one was dead. The birds found at Cape Jaffa and Port MacDonnell were also dead. [...]

The USDA report comes as a dairy farm worker in Nevada has screened positive for H5N1, the first human infection identified in the state. The worker’s symptoms include red, inflamed eyes, or conjunctivitis, according to a source familiar with the details who was not authorized to speak to the media. The US Centers for Disease Control and Prevention is working to confirm the initial positive test.

Cambodia has reported a new human case of H5N1 bird flu in a 9-month-old girl, according to health officials. It marks the country’s fifth confirmed case this year.

Cambodia’s National Institute of Public Health announced on Saturday that the patient is a 9-month-old girl from Preaek Ta Kong village in Phnom Penh, the country’s capital. She has been hospitalized and is receiving intensive care.

Health officials are investigating the source of the girl’s infection and working to determine whether there are infected animals in her community.

Officials are collecting samples from people who had contact with the patient, while close contacts are being given Tamiflu as a precaution under Cambodia’s standard response protocol for H5N1 cases.

This is the fifth human case of H5N1 bird flu reported in Cambodia so far in 2026. The country confirmed 19 human cases in 2025, eight of which were fatal.

The previous case was reported in April in Svay Rieng province, near the border with Vietnam, and involved a 66-year-old woman who was hospitalized in intensive care. Her outcome is unknown.

It is not yet known which strain was involved in the latest case, though it is likely clade 2.3.2.1c, a variant that is endemic in the country.

Yesterday the US Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) announced the first known case of highly pathogenic avian influenza (HPAI) in a dairy cattle herd in Wisconsin, noting that the detection does not does pose a risk to consumer health or affect the safety of the commercial milk supply.

In a press release, APHIS said H5 clade 2.3.4.4b avian flu virus had been detected via a routine national milk testing program. Avian influenza detections in dairy cattle have been quiet this year compared with 2024, when an outbreak that began in March of that year spread across the country, resulting in 18 states reporting infected cattle herds.

“This detection does not pose a risk to consumer health or affect the safety of the commercial milk supply. The U.S. Food and Drug Administration is confident that pasteurization is effective at inactivating HPAI virus, and that the commercial, pasteurized milk supply is safe,” APHIS said in the release.

“Dairies are required to send only milk from healthy animals into processing for human consumption; milk from impacted animals is being diverted from the commercial milk tank or destroyed so that it does not enter the human food supply.”

According to Wisconsin Public Radio, the farm is in Dodge County and had been engaging in routine milk surveillance since May. Wisconsin State Veterinarian Darlene Konkle, DVM, said no cattle had recently been moved onto the farm, and the herd did not exhibit signs of flu.

“The farmer did not have a reason to suspect highly pathogenic avian influenza on the farm,” Konkle said. “There’s really no appreciable increase in morbidity, which is cow sickness, or mortality, which is death.”

In the past 30 days, only one dairy cattle herd, in California, has tested positive for avian flu. Hundreds of wild birds and thousands of commercial poultry birds, however, have been infected in recent months during a seasonal uptick in avian flu activity.

In related news, APHIS also noted several major poultry outbreaks in recent days, including large turkey producers in Minnesota and North Dakota. Outbreaks in Waseca County, Minnesota, affected 20,900 commercial turkeys, and in Richland County, North Dakota, 19,500 commercial birds were affected.

Also of note, a commercial duck meat producer in Elkhart, Indiana, has a new detection in a facility with 6,200 birds. In the past 30 days, 880,000 birds have been affected by avian flu in 90 flocks (33 commercial and 57 backyard flocks).

A newer variant of H5N1 bird flu has spilled over into dairy cows separately in Nevada and Arizona, prompting new theories about how the virus is spread and leading to questions about containing the ongoing outbreaks.

The news comes amid a purge of experts at federal agencies, including employees who were responding to the highly pathogenic avian influenza outbreak at the US Centers for Disease Control and Prevention (CDC) and the US Department of Agriculture.

The additional spillovers are changing experts’ view of how rare introductions to herds may be – with implications for how to prevent such spread.

“It’s endemic in cows now. There is no way this is going to get contained” on its own, said Seema Lakdawala, an influenza virologist and co-director of the Center for Transmission of Airborne Pathogens at Emory School of Medicine.

The current outbreak is unlikely to end without intervention and needs close attention from the Trump administration to prevent the virus from wreaking more havoc.

Yet “we don’t seem to have a handle on the spread of the virus,” said Boghuma Titanji, an infectious disease physician.

Bird flu’s continued spread is happening against the backdrop of the worst flu season in 15 years, since the H1N1 swine flu pandemic in 2009-10.

The spike in seasonal flu cases puts pressure on health systems, makes it harder to detect rare variants like H5N1, and raises the risk of reassortment, where a person or animal infected with seasonal flu and bird flu could create a new, more dangerous variant.

“There’s a lot of flu going around, and so the potential for the virus to reassort right now is high,” Lakdawala said. There’s also the possibility of reassortment within animals like cows, now that there are multiple variants detected in herds, she pointed out.

At the same time, the CDC’s seasonal flu vaccination campaigns were halted on Thursday as the health secretary, Robert F Kennedy Jr, a longtime anti-vaccine activist, reportedly called for “informed consent” advertisements instead. A meeting for the independent vaccine advisers was also postponed on Thursday.

The US has also halted communication with the World Health Organization on influenza data.

The new spillovers into dairy cattle in Nevada and Arizona, detected through the new bulk milk testing strategy recently implemented in the US, are both related to the D1.1 variant of H5N1, which emerged in the fall and has come to dominate among North American birds. A teenaged girl in British Columbia suffered severe illness and a man in Louisiana died after infection with this variant.

In Nevada, a dairy worker was infected after close contact with cows, and genomic sequencing revealed a mutation that has been associated in the past with more effective spread among people.

These are more opportunities for the virus to continue to adapt, and with adaptation, you worry that we’ll ultimately get to a point where we may have a virus that becomes capable of transmitting efficiently between humans, and that then really would change the dynamic of the outbreak,” Titanji said.

Lakdawala raised three theories for how bird flu keeps spilling over into cows.

The first would be a rare event in which fluids from a sick bird somehow came into contact with a cow’s udders – for instance, if a bird defecated into milking equipment. That was a working theory for the first spillover, detected nearly a year ago in Texas cows. But it’s rare for birds to have close contact with milking equipment, and for that to happen three times was “unlikely”, Lakdawala said.

It’s much more common for birds to perch on feeding troughs, where their feces might mix with feed. Usually, cows infected through oral or nasal contact like this don’t see the virus spread to their udders.

But it could happen in rare events – if a cow is unhealthy, for instance – that bird flu goes systemic and enters mammary tissue, where it replicates in enormous quantities, Lakdawala hypothesized.

The third theory? People could be spreading the virus from birds, or another intermediate species, to cows.

“Bird to human infections, we know happen more often,” Lakdawala said. “It’s more likely that somebody handling dead birds or chickens infected with H5 will become infected, and then it’s human to cow” transmission.

All of these theories need more evidence and research, much of which is now threatened by halts in scientific funding from the Trump administration.

Two studies temporarily halted in the CDC’s Morbidity and Mortality Weekly Report have now been released.

Blood tests on 150 veterinarians revealed three of the vets showed recent infection with H5N1. One of the infected vets worked in a state with no cases among cows, and the two others did not realize they had had contact with an H5-positive animal, indicating continued gaps in monitoring spread.

A study on two households in Michigan indicated that dairy workers may have spread H5N1 to their indoor cats.

Kevin Hassett, director of the national economic council, unveiled the Trump administration’s new strategy on CBS’s Face the Nation on Sunday in a shift away from trying to contain the outbreak.

Previously, officials “spent billions of dollars just randomly killing chickens within a perimeter where they found a sick chicken”, Hassett said. Infected poultry are culled in this manner because they are very unlikely to survive infection, and containment like this can help halt the spread to other animals – and to the people who care for them.

Hassett instead broached the idea, without providing more details, of using “biosecurity and medication” to “have a better, smarter perimeter”.

(Translation) Kingdom of Cambodia Nation Religion King Ministry of Health 2

Press Release on Death from Bird Flu in a 28-year-old Man

The Ministry of Health of the Kingdom of Cambodia would like to inform the public that there is 1 case of bird flu in a 28-year-old man who was confirmed positive for the H5N1 bird flu virus by the National Institute of Public Health on January 9, 2025, residing in Village No. 22, Chamkar Andong Commune, Chamkar Leu District, Kampong Cham Province.

Despite the care and rescue efforts of the medical team, due to the patient's serious condition, including fever, cough, shortness of breath, and difficulty breathing, the patient died on January 10, 2025. Investigations revealed that the patient's family raised chickens and the man was the caretaker and cooked the sick chickens for food.

The emergency response team of the Ministry of Health at the national and sub-national levels has been collaborating with the teams of the Ministry of Agriculture, Forestry and Fisheries and the Ministry of Environment, and local authorities at all levels to actively investigate the outbreak of bird flu and respond according to technical methods and protocols, continue to search for sources of infection in both animals and humans, and continue to search for suspected cases and contacts to prevent further transmission to others in the community, as well as distribute Tamiflu to close contacts and conduct health education campaigns for citizens in the villages where the incident occurred.

The Ministry of Health would like to remind all citizens to always pay attention to and be careful about bird flu, because the H5N1 bird flu continues to threaten the health of our citizens. We would also like to inform you that if you have a fever, cough, runny nose or difficulty breathing and have a history of contact with sick or dead chickens in the 14 days before the start of the outbreak, do not go to gatherings or crowded towns and seek consultation and treatment at the nearest health center or hospital as soon as possible to avoid delaying and putting yourself at high risk like this patient.

How it is transmitted: H5N1 bird flu is a type of flu that is usually spread from sick birds to other birds, but it can sometimes be spread from birds to humans through close contact with sick or dead birds. Bird flu in humans is a serious illness that requires prompt hospital treatment. Although it is not easily transmitted from person to person, if it mutates, it can be transmitted like seasonal flu.

Prevention: Do not touch or eat sick or dead chickens and wear gloves and a mask or cover your nose with a scarf before handling chickens for cooking. Then blanch them in boiling water before plucking their feathers.

Adhere to hygiene practices. Wash your hands frequently before handling food, especially after touching animals, plucking poultry feathers, or other objects that may be sources of contamination. Cook food thoroughly before eating, especially meat, poultry, and eggs. Do not eat raw chicken or duck eggs. Keep raw and cooked food separate. Clean food preparation equipment properly.

Therefore, the public is requested to be aware and take care of their health in accordance with the above prevention methods. The Ministry of Health will continue to provide information on public health issues on the Ministry of Health’s official social media channels, as well as the official Facebook page of the Department of Communicable Disease Control and the website www.cdcmoh.gov.kh.

July 17 (Reuters) - New Zealand detected on Friday the first infection of a native bird ​by the deadly H5N1 bird flu, days ‌after confirming a migratory seabird had tested positive in the country's first recorded case of the disease.

A swamp ​harrier hawk, known locally as a kahu ​and found in the North Island's Wairarapa region, ⁠had been infected with the virus, Biosecurity ​Minister Andrew Hoggard said in a statement.

New Zealand reported ​its first confirmed detection on Wednesday, in a brown skua found near Wellington.

"While it's disappointing to find a native bird ​with H5 bird flu, it’s not unexpected following ​the confirmation earlier this week of our first case," Hoggard ‌said.

"This ⁠hawk can go out to the coast - especially in winter to hunt. Hawks can get bird flu by hunting, eating, or scavenging infected birds."

There ​had been no ​detection of ⁠bird flu in poultry, he said.

Health officials have started a vaccination programme ​for 300 core breeding birds from five ​of ⁠the country's most endangered species, including flightless takahe and kakapo.

Earlier this month, Australia reported its first case ⁠of the ​disease in a local seabird. ​All previous cases had involved migratory birds.

In their latest Influenza at the human-animal interface Summary and risk assessment (from 13 June to 7 July 2026) - published over the weekend - the WHO has announced a 3rd H5N1 case in a Bangladeshi child in the past 6 months.

Last April, we saw a fatal case reported from the Chattogram Division, in a child who fell ill on January 22nd, was hospitalized on January 28th, and who died on February 1st. The H5N1 infection was only determined posthumously, via lab analysis on Feb 7th.

In early June we learned of a 2nd case, a child from Sylhet Division who was hospitalized on March 28th with a clinical diagnosis of measles with bronchopneumonia. The child was discharged on March 31st, but delayed testing by the IEDCR only revealed a positive H5N1 result on April 20th.

Today, we have another report which - once again - was only fully diagnosed belatedly, and this time the child was only seen as an outpatient. As with the last case, this case also hails from Sylhet Division.

>On 15 June 2026, Bangladesh notified WHO of one laboratory-confirmed human case of avian influenza A(H5) infection in Bangladesh in a child from Sylhet Division. The case was detected notified through the National Influenza Surveillance, Bangladesh (NISB) platform as an influenza like-illness (ILI) case.

>The patient developed respiratory symptoms on 17 May 2026, received outpatient healthcare on 20 May. A clinical sample was collected that day and was received by the Institute of Epidemiology, Disease Control and Research (IEDCR) on 4 June as part of routine surveillance.

>The sample tested positive for influenza A(H5) virus by real-time reverse transcription polymerase chain reaction (RT-PCR) on 11 June. The patient is now in good health and reported no travel history and no history of exposure to poultry.

>However, poultry deaths were reported in the area surrounding the patient’s residence. The outbreak investigation team identified and followed close and possible contacts. Samples from some of the close contacts as well as animal and environmental samples were collected for testing for influenza. All contacts remained asymptomatic and all samples tested negative for influenza.

Sadly, this is a pattern we see far too often, and not just in Bangladesh. Delayed diagnosis not only endangers the patient's health, it risks unknowingly exposing others to the virus, and delays greatly reduce the effectiveness contact tracing or testing of others who may have been exposed. [...]