Category: Flu Virus

Cows are seen on a dairy farm in Virginia on October 5, 2022. Brendan Smialowski/AFP via Getty Images hide caption

Cows are seen on a dairy farm in Virginia on October 5, 2022.

Federal officials say the risk to the public remains low after the Food and Drug Administration announced Wednesday that tests of commercially available milk detected traces of bird flu.

The announcement comes amid a national outbreak of highly pathogenic avian influenza (HPAI) among dairy cows that was first confirmed late last month. The disease, which is very contagious and often fatal in avian populations, has spread to herds in at least eight states. At least one person who was in contact with presumably sick animals also caught the virus.

But government officials and scientific experts say so far there is no evidence of infectious virus in pasteurized milk.

National Institute of Allergy and Infectious Diseases director Jeanne Marrazzo said Wednesday in a call with reporters that tests conducted on retail milk showed that there was genetic material from the virus.

Efforts to grow the virus from those samples indicated that the virus was not infectious or "alive," Marrazzo said, adding that testing was only conducted on a small set of samples.

"To date, we have seen nothing that would change our assessment that the commercial milk supply is safe," the FDA said in a statement.

Pasteurization has been used in the U.S. for decades to kill harmful bacteria and viruses in milk, but pasteurization may not erase all traces of a virus.

Some genetic material may be left behind after the pasteurization process, such as DNA or RNA, the "instructions" that tell the virus what to do, according to Cornell University food science professor Samuel Alcaine.

"A car gets in an accident. It's no longer functioning. You can't drive it. It doesn't do anything that a car does. But you sift through the rubble and you could still find the instruction manual that tells it how to work," he said.

Alcaine said that's likely what's happening with bird flu in milk: Tests show the virus used to be there, but it's no longer able to cause an infection.

The FDA said there haven't been any studies specifically on whether pasteurization inactivates bird flu in cow's milk because bovine infections are so new. However, it added that previous studies have shown that pasteurization is "very likely to effectively inactivate heat-sensitive viruses, like H5N1" and that pasteurization has inactivated bird flu in eggs, a process that occurs at a lower temperature than for milk.

The FDA said it detected bird flu in milk using quantitative polymerase chain reaction (qPCR) tests, which "do not represent actual virus that may be a risk to consumers."

Further evaluation of milk samples will be done using egg inoculation tests, the FDA said, which it called the "gold-standard for determining viable virus." The agency said it would release the results from multiple studies within days or weeks.

"There are no safety concerns," Alcaine said of milk with traces of bird flu. "I'm still buying my milk from my local grocery store."

Federal officials emphasize that any milk from infected cows is supposed to be discarded or destroyed and not enter the human food supply.

On top of that, any milk sold via interstate commerce in the U.S. is required to be pasteurized. The FDA has encouraged consumers not to drink raw, unpasteurized milk.

But Alcaine said influenza is generally not transmitted through food, and the more pressing concern is protecting people like farm workers, who could come into close physical contact with infected animals.

In an attempt to further contain the outbreak, the USDA's Animal and Plant Health Inspection Service announced an order Wednesday that requires dairy cows to test negative for bird flu before they can be moved across state lines, among other measures.

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What consumers should know about the milk testing positive for bird flu - NPR

The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) today reported the first H5N1 avian flu virus detection in Colorado's dairy cows, raising the number of affected states to nine.

Also today, the World Health Organization (WHO), the World Organization for Animal Health (WOAH), and the UN Food and Agriculture Organization (FAO) weighed in on recent H5N1 developments in the United States and abroad. They said evolving developments with the virus, including a novel reassortant detected in three Asian countries and a spillover from wild birds to dairy cows in the United States, requires real-time monitoring.

The H5N1 detection in Colorado raises the number of herds known to be affected to 34. So far, there are no details on where the Colorado herd is located and how it may have been exposed to the virus.

Recent detections of H5N1 remnants in retail milk suggest that the virus in dairy cows may be more widespread than suggested by current animal testing.

The three global agencies raised concerns about genetic diversification of the H5N1 2.3.4.4b clade spreading in multiple world regions, as well as its ability to infect a broader range of species, with some species experiencing significant death rates, such as in sea mammals in South America.

As the virus infects more species, including a goat and dairy cows in the United States, the virus has more opportunities to generate new genotypes, which could cause different clinical pictures.

For example, the global experts said a novel H5N1 reassortant seen in poultry in Cambodia, Laos, and Vietnam over the past 2 years has now been detected in humans, one from Cambodia and the other from Vietnam. The virus contains surface proteins from an older H5N1 clade (2.3.2.1c) and internal genes from the more recent 2.3.4.4b H5N1 clade.

The WHO, WOAH, and FAO said the overall risk to humans remains low, and for people who have exposure to infected animals or their environments, the risk is low to moderate.

In other H5N1 developments:

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H5N1 avian flu infects Colorado dairy cows as global experts weigh in on virus changes - University of Minnesota Twin Cities

The discovery of fragments of avian flu virus in milk sold in U.S. stores, including in about 20% of samples in initial testing across the country, suggests that the H5N1 virus may be more widespread in dairy cattle than previously realized.

The Food and Drug Administration, which announced the early results from its nationally representative sampling on April 25, 2024, was quick to stress that it believes the commercial milk supply is safe. The FDA said initial tests did not detect any live, infectious virus. However, highly pathogenic avian influenza virus can make cows sick, and the flu viruss presence in herds in several states and new federal restrictions on the movement of dairy cows between states are putting economic pressure on farmers.

Five experts in infectious diseases in cattle from the University of California, Davis Noelia Silva del Rio, Terry Lehenbauer, Richard Pereira, Robert Moeller and Todd Cornish explain what the test results mean, how bird flu can spread to cattle and the impact on the industry.

Its crucial to understand that the presence of viral fragments of H5N1 doesnt indicate the presence of intact virus particles that could cause disease.

The commercial milk supply maintains safety through two critical measures:

First, milk sourced from sick animals is promptly diverted or disposed of, ensuring it does not enter the food chain.

Second, all milk at grocery stores is heat treated to reduce pathogen load to safe levels, mainly by pasteurization. Pasteurization has been shown to effectively inactivate H5N1 in eggs, and that process occurs at a lower temperature than is used for milk.

The viral fragments were detected using quantitative polymerase chain reaction testing, which is known for its exceptional sensitivity in detecting even trace amounts of viral genetic material. These fragments are only evidence that the virus was present in the milk. They arent evidence that the virus is biologically active.

To evaluate whether the presence of the viral fragments corresponds to a virus with the capacity to replicate and cause disease, a different testing approach is necessary. Tests such as embryonated egg viability studies allow scientists to assess the viruss ability to replicate by injecting a sample into an embryonated chicken egg. That type of testing is underway.

On April 24, 2024, the FDA said it had found no reason to change its assessment that the U.S. milk supply is safe. The agency does strongly advise against consuming raw milk and products derived from it because of its inherent risks of contamination with harmful pathogens, including avian flu viruses.

Currently, cows confirmed to have H5N1 have different symptoms than the typical flu-like symptoms observed in birds.

Abnormal milk and mastitis, an inflammatory response to infection, are common. While there is speculation that other bodily secretions, such as saliva, respiratory fluids, urine or feces, may also harbor the virus, that has yet to be confirmed.

How waterfowl or other birds transmitted H5N1 to cattle is still under investigation. In 2015, an outbreak of highly pathogenic avian influenza in commercial poultry farms reached its peak in April and May, the same time birds migrated north. Birds can shed the virus through their oral, nasal, urine and fecal secretions. So the virus could potentially be transmitted through direct contact, ingesting contaminated feed or water, or inhaling the virus.

Infected dairy cows can shed the virus in milk, and they likely can transmit it to other cows, but that still needs to be proven.

Contagious pathogens that cause mastitis can be transmitted through milking equipment or contaminated milkers gloves. Ongoing research will help determine whether this is also a potential transmission route for H5N1, and if so, what makes the virus thrive on mammary tissue.

For the dairy industry, infection of cattle with H5N1 avian influenza virus creates challenges at two levels.

The overriding concern is always for the safety and healthfulness of milk and dairy products.

Existing state and federal regulations and industry practices require sick cows or cows with abnormal milk to be segregated so that their milk does not enter the food supply. Proper pasteurization should kill the virus so that it cannot cause infection.

The American Association of Bovine Practitioners has also developed biosecurity guidelines for H5N1, focusing on key practices. These include minimizing wild birds contact with cattle and their environment, managing the movement of cattle between farms, isolating affected animals, avoiding feeding unpasteurized (raw) colostrum or milk to calves and other mammals, and ensuring the use of protective personal equipment for animal caretakers.

The other major concern is for the health of the dairy herd and the people who take care of the dairy cattle. A farm worker who handled dairy cows contracted H5N1 in Texas in March 2024, but such cases are rare.

No vaccines or specific therapies are available for avian influenza infections in dairy cattle. But following good sanitation and biosecurity practices for both people and cows will help to reduce risk of exposure and spread of the avian influenza virus among dairy cattle.

For cows that get the virus, providing supportive care, including fluids and fever reducers as needed, can help them get through the illness, which can also cause loss of appetite and affect their milk production.

Dairy farms facing an outbreak will have economic losses from caring for sick animals and the temporary reduction in milk sales. Approximately 5% to 20% of the animals in the affected herds have become ill, according to early estimates. Affected animals typically recover within 10 to 20 days.

At least 22 states have restricted importing dairy cattle to prevent the viruss spread, and the federal government announced it will require that lactating dairy cattle be tested before they can be moved between states starting April 29, 2024. While the overall impact on U.S. milk production is projected to be minor on an annual basis, it could lead to short-lived supply disruptions.

The federal governments monitoring and food safety measures, along with pasteurization, provide important safeguards to protect the public from potential exposure to avian influenza virus through the food chain.

Drinking raw milk, however, does represent a risk for exposure to multiple diseases, including H5N1. This is why the FDA and Centers for Disease Control and Prevention strongly recommend drinking only pasteurized milk and dairy products.

This article, published April 25, 2024, has been updated with new FDA test results.

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How bird flu virus fragments get into milk sold in stores, and what the spread of H5N1 in cows means for the dairy ... - The Conversation

News that bird flu has been spreading between cows for months and that fragments of the virus are even showing up in milk on U.S. grocery store shelves have fueled new worries about the risk the virus poses to people. Among the questions: Is the virus, known as highly pathogenic avian influenza H5N1, adapting to better infect mammals? And can people get bird flu from drinking that milk?

Science News went to the experts to find answers to those questions. The short answer is that, thanks to milk pasteurization and the way bird flu viruses spread, the risk to people remains low. Heres a deeper dive into what you should know.

Probably not in pasteurized milk.

On April 23, the U.S. Food and Drug Administration announced that fragments of the bird flus genetic material had turned up in grocery store milk. Initial results indicate that about 1 in 5 samples contain bitsof the viruss RNA,the agency announced April 25. Samples taken from areas where infected dairy cows have been found were more likely to test positive for the bird flu virus than those with no infected herds.

That doesnt mean that whole infectious viruses are present, says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota in Minneapolis.

At first blush, it would surely seem as if it should be a great concern in terms of human health. However, the good news is that while the virus is in the milk the pasteurization process actually is very effective in killing those virus particles so that in fact, we dont have to be concerned about Are we ingesting infective material?

Pasteurization raises milk to a high enough temperature to kill bacteria and viruses. Milk has always had bits of dead bacteria such as E. coli and Listeria that arent filtered out, Osterholm says. So its not surprising to find genetic remains of the flu virus, he says, but that by itself does not at all suggest a public health concern.

H5N1 is an envelope virus. And envelope viruses ones that wrap themselves in a blanket borrowed from a host cells membrane are just a little bit wimpier than non-envelope viruses and a little bit easier to inactivate, says Meghan Davis, an environmental epidemiologist at the Johns Hopkins Bloomberg School of Public Health. That means that theres some reassurance that pasteurization ought to be working.

Because H5N1 has only recently been found in cattle, no studies have directly tested milk pasteurizations ability to kill the virus, the FDA said in a statement April 23. But studies have shown that egg pasteurization, which is done at lower temperatures than milk pasteurization, inactivates the virus.

For those reasons, government officials stress that pasteurized milk is safe to drink. But the FDA recommends that people dont drink raw milk, which has not been pasteurized.

Davis says there are many reasons to avoid raw milk and products made from it. We know that raw milk [can contain] other infectious diseases and there have been outbreaks linked to raw milk consumption. So categorically I dont recommend it.

Some goats have also been infected with H5N1, so Davis suggests avoiding raw goat and sheep milk products, too.

Decades of evidence suggest thats not likely, Osterholm says.We have no evidence that humans have become infected from influenza A virus via ingestion.

Some scavenger mammals have become infected with H5N1 from eating dead birds. But to get into cells, influenza viruses need to grab onto receptors, cell surface proteins studded with certain sugars. In humans, those sugars are different than the versions in scavengers. People carry the entry portals in their upper respiratory tract and the eyes. The one person in the United States who recently caught bird flu worked with cows at a farm in Texas and was diagnosed with conjunctivitis, an eye infection.

It might even be difficult for people to catch the bird flu from infected cows, Osterholm says. If you look at the experience weve had in the past, even with all of the human contact that occurred with infected flocks [of] turkeys and chickens over the course of the past several years, weve just seen an absence of infection in humans. Both the U.S. Centers for Disease Control and Prevention and World Health Organization have designated the virus as low risk for humans.

The U.S. Department of Agriculture first announced finding a strain of bird flu in dairy cattle in Kansas and Texas on March 25 (SN: 4/3/24). Since then, the virus has been found in dairy cows in eight states. The same version of the virus infecting cows called clade 2.3.4.4b has also been found in poultry in five states, the USDA said in a federal order. That order announced mandatory testing for all dairy cows before they can be moved to another state, and also requires tracing the previous movements of cows from infected herds. The order will go into effect on April 29.

H5N1 may have jumped into cattle only once and then spread from cow-to-cow, evolutionary biologist Michael Worobey of the University of Arizona in Tucson posted on X (formerly Twitter) after he and colleagues analyzed 239 bird flu viruses from cattle and other species. The jump may have happened in late December 2023, months earlier than thought.

These findings are still preliminary and havent been independently verified by other scientists, Davis cautions. But they do suggest that bird flu in cattle is probably more widespread than what weve identified based on the reported cases on the USDA dashboard. What were looking at is probably circulation, potentially cow-to-cow, but we dont yet know the extent.

At the moment we have both concern and reassurance, she says. Despite the low risk, we have the concern that this particular H5N1 has had staying power and has been around globally since 2020. It has been in the U.S. since 2022. The virus continues to cause major outbreaks in birds and has jumped into many species of mammals. That pattern is different from what was seen with earlier iterations of H5N1 avian influenza. It would flash up, wed have cases and then it would die off by the next year. But thats not what were seeing here.

Yes, but cases tend to be fairly mild. H5N1 infections in cows can cause a drop in appetite and milk production, abnormal feces, tiredness, fever and other symptoms.

Davis, a former dairy veterinarian, says that vets often get calls that cows are off feed, meaning the animals arent eating well or giving as much milk as usual. Those symptoms are not specific to any particular disease, so cases of H5N1 influenza may easily have been overlooked.

Some cows may not have any symptoms. Lung tissue taken from one cow with no symptoms tested positive for the virus, the USDA announced April 24.

The virus has also been found in cats on dairy farms in Texas and in Poland, South Korea and France. At least one cat died, according to the World Organization for Animal Health.

For poultry such as chickens and turkeys, the virus can be deadly, destroying flocks in a matter of days.

Possibly, Osterholm says. In our business, we almost sleep with one eye open, just because on any one given day there could be a change in the virus from mutation or reassortment.

Reassortment happens when flu strains swap part of their genetic instructions. Reassortment generated the H1N1 flu strain that caused a pandemic in 2009. In a pig, bits from the 1918 pandemic flu strain combined with pieces from a virus that was already a mish-mash of a swine flu virus and an avian flu virus. The resulting virus eventually infected people (SN: 5/22/09; SN: 2/12/10). The current H5N1 resulted from the reassortment of avian influenza viruses from poultry and wild birds.

What we are concerned about is adaptation of the virus to better suit some of the receptors that humans might have, which is why any transmission out of bird populations into any mammal is initial cause for concern, Davis says. People working on dairy farms, those in the dairy production chain and anyone else who may come into contact with raw milk, cows or poultry should wear protective equipment to avoid possible infection. She also advocates for testing farm workers, their families and others in their communities.

Both Davis and Osterholm are concerned about the virus infecting other food animals.

The challenge that I see right now on U.S. farms is a virus getting into hogs, Osterholm says. Pigs carry receptors similar to the ones found in both humans and birds, making swine a hog-heaven for bird flus that have potential to become a pandemic. Meanwhile, Davis says, if this virus can infect both cows and goats, sheep are on my suspicion list for another potential species of concern.

H5N1 avian influenza viruses have been found in birds since 1996 and have infected more than 880 people globally since 1997. In the United States, a poultry worker tested positive for H5N1 in 2022. The dairy farmworker with conjunctivitis was only the second person in the United States with a documented bird flu infection.

So far, H5N1 has not developed the ability to spread easily from person-to-person, which would make it a pandemic-potential virus. Lightning could strike tomorrow, Osterholm says, but at least based on the track record so far, theres been very little evidence to support that this is going to infect humans [and] then be transmitted by people to other people.

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Traces of bird flu are showing up in cow milk. Here's what to know - Science News Magazine

(CNN) A new study finds spikes in Flu virus in wastewater could be linked to the spread of Bird Flu affecting cattle.

The spikes of influenza virus were seen in wastewater samples from 59 sewer systems across 18 states this spring.

So far, the U.S. Department of Agriculture has reported more than 30 herds of diary cows infected with H5N1 Bird Flu in 9 states.

The researchers notes the H5 genetic material theyre picking up in the wastewater could come from sources other than diary cattle.

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Spike: Flu spike in wastewater may be linked to Bird Flu - Abccolumbia.com

The USDA and FDA said the commercial milk supply remains safe for now.

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April 24, 2024, 9:41 AM ET

4 min read

As federal agencies and state partners continue investigating outbreaks of highly pathogenic avian influenza (HPAI) -- more commonly referred to as bird flu -- the U.S. Food and Drug Administration says it discovered fragments of the virus in some samples of milk.

In an update from the FDA, the agency said it tested milk samples by polymerase chain reaction (PCR) and found the presence of fragments of the virus, which is not the same as infectious virus and currently poses no increased risk to human health.

"Based on available information, pasteurization is likely to inactivate the virus, however the process is not expected to remove the presence of viral particles," the FDA said.

"At this point, when you look for something in public health, science and medicine, your chances of finding it go up," ABC News chief medical correspondent Dr. Jennifer Ashton said.

Citing a senior official at the Centers for Disease Control and Prevention, Ashton said, "the overall risk to the general American population is low, particularly from dairy cows, however, 'they are taking this very seriously.'"

Importantly, the FDA stated, "we have seen nothing that would change our assessment that the commercial milk supply is safe" and expect new results from multiple studies "in the next few days to weeks."

Concerns were first raised last month when HPAI was detected in dairy cows across multiple states, but the USDA and FDA maintain that the U.S. commercial milk supply remains safe due to "the pasteurization process and the diversion or destruction of milk from sick cows."

"Nearly all (99%) of the commercial milk supply that is produced on dairy farms in the U.S. comes from farms that participate in the Grade 'A' milk program and follow the Pasteurized Milk Ordinance (PMO), which includes controls that help ensure the safety of dairy products," the FDA update continued.

Aside from pasteurized milk, both the FDA and CDC warn against drinking raw milk or products made with it that are typically bought at farms or local stores, due to possible viruses or bacteria that can lead to infection or foodborne illness.

Twenty states explicitly prohibit raw milk sales in some form. And milk that travels across state lines must be pasteurized, according to federal regulations.

HPAI was first detected in 1996 and there have only been two cases of human H5N1 in the U.S. so far. There have been no reports of human-to-human spread in the U.S.

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Traces of bird flu virus found in some milk and pasteurized dairy, FDA says - ABC News

TUESDAY, April 30, 2024 (HealthDay News) -- As bird flu continues to spread among dairy cows, the U.S. Department of Agriculture said Monday it is now testing ground beef for any presence of the virus.

The agency said it is sampling ground beef bought in grocery stores in states where dairy cattle have tested positive for the virus, also known as H5N1, CNN reported. Officials are also testing samples of muscle tissue from sick cows that have been culled from their herd.

Last but not least, the USDA is injecting a virus surrogate into ground beef and then cooking it at different temperatures, to see how much virus is killed under each heat setting.

Still, the agency stressed this testing does not mean the beef supply isn't safe.

USDA is confident that the meat supply is safe. USDA has a rigorous meat inspection process and multiple safeguards in place to protect consumers, the agency said in a statement, CNN reported.

We recommend consumers properly handle raw meats and cook to a safe internal temperature, which kills germs in meat, the agency added.

U.S. health officials are already testing retail milk samples for live bird flu virus, and none has been found in any of the first batch of samples tested, federal health officials said Friday.

Those early findings should reassure the public that the milk sold in stores remains safe, officials added.

In the online update, the U.S. Food and Drug Administration said the initial test findings likely mean the pasteurization process is killing the virus.

These results reaffirm our assessment that the commercial milk supply is safe, the agency wrote, but testing efforts are continuing.

"The FDA is further assessing retail samples from its study of 297 samples of retail dairy products from 38 states," the agency added. "All samples with a PCR-positive result are going through egg inoculation tests, a gold standard for determining if infectious virus is present."

"These important efforts are ongoing, and we are committed to sharing additional testing results as soon as possible," the FDA added.

FDA officials also tested infant and toddler formulas, which used powdered milk, and did not find any evidence of the virus, the agency noted.

The story is different when it comes to viral fragments of bird flu: genetic bits of the virus have been discovered in roughly 20% of retail milk samples tested in a national survey, the U.S. Food and Drug Administration said last week.

That earlier finding suggests bird flu has spread far more widely among dairy cows than officials first thought.

Samples from parts of the country that have infected dairy herds were more likely to test positive, the agency noted, and regulators stressed there is no evidence yet that cow milk poses a danger to consumers.

Still, 33 herds across eight states have been confirmed to have been infected with bird flu, also known as H5N1.

It suggests that there is a whole lot of this virus out there, Richard Webby, a virologist and influenza expert at St. Jude Childrens Research Hospital, told the New York Times.

While it is still possible to eradicate bird flu from the nations dairy farms, Webby noted it is hard to control the outbreak without knowing its full scope.

To that end, the USDA announced last week that it is now requiring mandatory testingof dairy cows moving across state lines. Before that, testing of cows had been voluntary and focused on cows with obvious symptoms of illness.

As of Wednesday, 23 people had been tested for the virus, while 44 people were being monitored after exposure to H5N1, the Times reported. Justone human infectionhas been reported so far, in a dairy worker in Texas who had direct contact with sick cows. The case was mild.

Still, sustained spread among cows would give the virus more chances to become more transmissible among humans.

Experts believe pasteurization, in which milk is briefly heated, should kill the virus.

And when you destroy the virus, its going to release genetic material, Samuel Alcaine, a microbiologist and food scientist at Cornell University in New York, told the Times.

Its not surprising to find them in milk, he added. It doesnt mean that the milk is not safe.

More information

The U.S. Centers for Disease Control and Prevention has more on bird flu.

SOURCES: U.S. Food and Drug Administration, updates, April 25/26, 2024; CNN; New York Times

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USDA Testing Beef Amid Bird Flu Outbreak in Dairy Cows - HealthDay

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Posted: April 30, 2024

While federal officials say there's still no sign of a dangerous form of bird flu in Canadian dairy cows, scientists warn limited surveillance means Canada might not be staying ahead of an explosive H5N1 outbreak among dairy cattle south of the border.

So far, dozens of herds across various U.S. states have been infected with this form of influenza A. While it appears to cause milder infections in cows, H5N1 has also been linked to stunning death rates of 50 per cent or more in other species, including various birds, catsand even humans, though more data and research is needed to fully understand the risks.

"I think we're way behind the virus," warned Matthew Miller, an immunologist and vaccine developer with McMaster University, who's among the Canadians working on H5N1 research.

Without a "robust national surveillance program, there's no way to know if there are infections here or not."

The Canadian Food Inspection Agency (CFIA) told CBC News on Mondayit has not detected this form of bird flu yet in dairy cattle or any other livestock in Canada. (In birds, however, the disease is already widespread across the country, impacting an estimated 11 million farmed birds to date.)

The disease is federally reportable in any species, cattle included, the CFIA said.The agency requires dairy producers to monitor for signs of infection, follow biosecurity measures, and contact their local CFIA office if there is a "high degree of suspicion" of the disease.

It appears that cross-country trade is still allowed. Asked whether dairy cattle can currently be transported between the U.S. and Canada, the CFIAsaid the World Organisation of Animal Health "does not recommend restrictions on the movement of healthy cattle and their products at this time."

As well, following a U.S. federal order last Wednesday requiring H5N1 testing for many dairy cattle moving between states, "Canada will also require testing for [avian flu] on imported lactating dairy cattle from the U.S.," the CFIA said.

When asked about testing milk samples, the agency said ifH5N1 is detected in Canadian cattle, it will help provide testing support.

(The agency was more clear in an earlier statement on social media, saying it is "not currently testing raw or pasteurized milk," addingthat the virus isn't a food safety concern.)

Multiple Canadian scientists, however, stressthat widespread testing and surveillance efforts should already be underwayrather than set to ramp up after a first detection.

Canada should "absolutely be doing active surveillance for H5N1 in cattle," other animals and humans who are in close contact with them, said Dr. Isaac Bogoch, an infectious diseases expert with the University Health Network in Toronto, in correspondence with CBC News.

He said those efforts could include a range of approaches such as wastewater surveillance, blood sample studiesand nasal swabs.

The goal should be going "all-in on prevention," Miller said, adding "pandemics always have the highest risk of happening when we have a virus in animals that humans are heavily exposed to."

Given H5N1's unprecedented leap into cattle, followed by explosive cow-to-cow spread across the U.S. in mere weeks, the potential for human-to-human transmission seems more likely as the virus adapts to more mammals, he warned.

"If we see more human infections, cat's out of the bag, it's way too late," Miller said. "We need to be sparing no amount of effort, and no amount of expense, in doing absolutely everything to prevent even those initial infections in humans because the stakes are just too high."

The U.S. has reported one human infection linked to the cattle outbreaks so far, in an individual whose only symptom was eye inflammation. However, some scientists have warned there are likely more that aren't being detected, amid growing calls for mass testing on farms.

WATCH | Texan contracts bird flu:

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"Since the issue in the [U.S.] seems to be bigger than we thought and was brewing before it was recognized, and since we have a plausible route for exposure here, we should be proactive," said Dr. Scott Weese, a professor at the Ontario Veterinary College and director of the University of Guelph's Centre for Public Health and Zoonoses.

At a minimum, he added, that would involve milk surveillance. It may not be particularly sensitivethe milk supply is diluted because it comes from so many farms, Weese said.

"But if there are positives, we know we have it and then need to look more aggressively at the farm level."

Despite sick cows being pulled from production lines, U.S. Food and Drug Administration officials said its recent nationwide survey of milk sold on store shelves found viral remnants of H5N1 in one in five samples. (More reassuringly, federal tests suggest pasteurization a heating process meant to neutralize harmful pathogens does ensure milk is safe to drink.)

On Monday, the U.S. Department of Agriculture (USDA) also announced there will be testing of ground beef in states with bird flu outbreaks, and recently warned the virus may be passing back and forth between cattle and poultry farms.

The first known cattle infected with H5N1 were reported in late March. Since then, at least 34 herds across nine U.S. states have been impacted, and scientists suspect the outbreak is already far bigger than official figures suggest.

Newly released research from the U.S. Centers for Disease Control and Prevention also showed profound impacts on farm cats with a death rate of around 50 per cent among those fed raw milk products from infected cows.

The study raises "new concerns regarding the potential for virus spread within mammal populations," the team continued.

WATCH | Quebec poultry industry suffers avian flu outbreaks:

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On Monday, other U.S. researchers shared a preprint research not yet formally published or peer-reviewed outlining efforts to monitor influenza A at dozens of wastewater sites this spring.

The team tested samples from three plants where spring rises in influenza A were observed, and found a marker for the H5 gene at all three facilities. Those plants were also located in an unnamed state with confirmed H5N1 outbreaks among dairy cattle, and two of the facilities discharged animal waste and milk byproducts into sewers, the researchers noted.

It all paints a picture of a fast-spreading outbreak that's impacting new species, appearing in new areas, and is likely past the point of containing, several outside scientists agreed.

Here in Canada, funding and support for veterinarians and farmers to test needs to be clear, stressed Weese.

"If farmers have to pay for sampling and testing, and don't know what will happen if there's a positive, and have no direct personal gain from it, why would they do it voluntarily?" he questioned. "We need a clear program that supports good testing and supports farms."

Toronto-based infectious diseases specialist Dr. Allison McGeer, from Sinai Health System, said she's "personally hoping we are not going to get caught off guard" here in Canada.

What's reassuring, McGeer added, is that Canada does have robust human testing in place to catch severe flu infections. Typically, she says, Canadian hospitals use combined viral testing for COVID, influenzaand RSV which can pick up a certain protein that is stable across all strains of influenza A.

If a human infection of avian flu showed up in a hospital, the test would label it along the lines of "influenza A, subtype not detected," she explained. And, if the patient had also been in contact with poultry or wildlife, that combination of factors could trigger extra lab work to pinpoint the specific type of influenza including H5N1.

But that's only if someone is sick enough to visit a healthcare facility.

"It's not a perfect system," McGeer acknowledged, "but it's [a sensitive system] for detecting severe disease from H5N1."

Lauren Pelley Senior Health & Medical Reporter

Lauren Pelley covers health and medical science for CBC News, including the global spread of infectious diseases, Canadian health policy, pandemic preparedness, and the crucial intersection between human health and climate change. Two-time RNAO Media Award winner for in-depth health reporting in 2020 and 2022. Contact her at: lauren.pelley@cbc.ca

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Scientists warn Canada 'way behind the virus' as bird flu explodes among U.S. dairy cattle - CBC.ca

The Food and Drug Administration (FDA) said last week that 1 in 5 retail milk samples across the U.S. showed genetic traces of bird flu virus. So why isn't it more concerned?

Highly pathogenic avian influenza is an infectious viral illness that spreads primarily among wild and domestic birds, but the virus that causes bird flu can sometimes jump into animals, including dairy cows and, in some cases, humans.

A "multistate outbreak" of the virus has emerged among dairy cattle since mid-March, according to the U.S. Centers for Disease Control and Prevention (CDC), and two cases have been confirmed in humans. But if 1 in 5 commercial milk samples is testing positive for the virus, why have we not heard any warning regarding its safety?

The method used to test the milk samples involved analyzing them for traces of genetic material that can be found in the circulating strain of the bird flu virus. But just because there are traces of its DNA doesn't mean the milk contains active forms of the virus itself.

Following these initial findings, the FDA conducted further analysis to determine whether any infectious virus was present in the samples. "This additional testing did not detect any live, infectious virus," the agency said in a statement on April 26. "These results reaffirm our assessment that the commercial milk supply is safe."

The FDA will continue to test positive milk samples as part of an ongoing study in coordination with the U.S. Department of Agriculture. However, its results so far have confirmed that "pasteurization is effective against this virus."

Pasteurization involves heating milk to a specific temperature to kill off any harmful bacteria or viruses it might contain. "Even if virus is detected in raw milk, pasteurization is generally expected to eliminate pathogens to a level that does not pose a risk to consumer health," the FDA said.

"Based on available information, pasteurization is likely to inactivate the virus," the agency said. "However, the process is not expected to remove the presence of viral particles."

The CDC will continue to monitor bird flu in people with animal exposure, but for now it is confident that "the current public health risk is low."

However, it still recommends the following actions to keep yourself safe from bird flu:

Is there a health problem that's worrying you? Do you have a question about eating meat? Let us know via health@newsweek.com. We can ask experts for advice, and your story could be featured in Newsweek.

Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.

Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.

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Bird Flu: Why FDA Says Milk Safe Despite 1 in 5 Positive Tests for Virus - Newsweek

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Lauren Pelley, Amina Zafar - CBC News

Posted: April 27, 2024

This story is part of CBC Health's Second Opinion, a weeklyanalysis of health and medical science news emailed to subscribers on Saturday mornings. If you haven't subscribed yet, you can do that by clicking here .

A dangerous type of bird flu virus discovered in the lung of a U.S. dairy cow that didn't show symptoms. Viral particles identified in processed, pasteurized milk. Genetic sequences showing distinct changes in this H5N1 strain that's been rapidly spreading throughout American cattle.

Those were just a handful of the rapid-fire developments this week as an unprecedented H5N1 outbreak among U.S. dairy cattle continued to evolve.

Scientists now warn this form of avian influenza is likely more widespread in cows, and was transmitting for longerthan official reports suggest. And while American officials are ramping up testing all in an effort to keep sick cows from being moved between states others say we're already several steps behind the spread of a disease that could pose a major threat to human health.

Michael Worobey, a researcher from B.C. who's now head of the department of ecology and evolutionary biology at the University of Arizona, said these cattle infections may have been "flying under our radar for months," providing ongoing opportunities for this virus to acquire adaptations that could lead to a flu pandemic.

"I think, in many ways, this is the biggest news story in the world right now."

After the U.S. Department of Agriculture posted more than 230 genetic sequences from the country's growing H5N1 outbreak last Sunday, Worobey was among the scientists racing to analyze the complex set of data.

The sequences were from cattle amid anoutbreak impacting more than two-dozen herds across nine U.S. states but also several bird species, cats, skunksand raccoons.

It's possible that local birds passed the virus to local farms, in different states, and they're all spreading a genetically similar lineage, he said. But Worobey believes what's far more likely is that the cattle outbreak has a single origin point.

In an interview with CBC News, he outlined H5N1's evolutionary tree, with a distinct branch of sequences linked to cattle. All those sequences share the same mutations, Worobey added.

"This is the hallmark of a single jump, that's at the root of this outbreak," he said.

And that jump likely occurred earlier than the first known cattle infections reported in late March.

A single introduction could have happened as far back as November or December, with a distinct lineage of H5N1 then spreading undetected for months, Worobey said. He added missing details in the initial U.S. data dump including exact cattle locations and dates madeit tough to know for sure.

The cattle sequences also contain "at least two distinct mutations" that are known for increasing the risk of a flu virus infecting and transmitting in humans, Worobey added.

"We just are producing more and more [opportunities] for evolution to arrive at something that can transmit in humans, and potentially kill a large proportion of them," he said.

What's not yet clear is how, exactly, the virus is spreading among cattle, though several scientists told CBC News that possibilities include close contact between cows being transported between states or contaminated milking equipment.

"If the cattle indeed have [infection] in the udders, then transmission could be through milking equipment," said Michelle Wille, a senior research fellow with the University of Melbourne's Centre for Pathogen Genomics andthe department of microbiology and immunology.

"A number of infected states have indicated that [avian flu] was detected in dairy herds that recently received cattle from Texas so transport of cattle is likely playing a role in spread."

At this point, it's still unclear how the virus is "sustaining transmission" in cattle populations, added virologist Angela Rasmussen, from the University of Saskatchewan's Vaccine and Infectious Disease Organization.

It's also likely the virus is being transmitted even when cows aren't showing symptoms which have so far been mild, including low appetite and reduced milk production several scientists agreed.

WATCH | Bird flu spreads in U.S. cows:

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This week, officials announced dual discoveries of H5N1 in the lung of an asymptomatic cow in North Carolina, along with viral particles in pasteurized milk, suggesting infected cows almost slipped into the food supply chain.

Ohio State University researchers also saidthey recently did their own independent sleuthing, collecting 150 commercial milk products from dairy processing plants across 10 states. The team found fragments of viral RNA in close to 60 samples nearly 40 per cent of the products, all of it available on store shelves.

Rasmussen stressed that the discovery of viral RNA in milk doesn't necessarily mean it can make people sickif it'sfragments of a virus, not something infectious. Dairy products also go through pasteurization, a heating process meant to eliminate a variety of pathogens.

But in a Thursday update, the U.S. Food and Drug Administration (FDA) said additional testing is still needed "to determine whether intact pathogen is still present and if it remains infectious, which would help inform a determination of whether there is any risk of illness associated with consuming the product.

The FDA added retail milk studies so far have shown no results that would change its assessment that the commercial milk supply in the U.S. is safe.

What's more concerning, Rasmussen said, is that these developments suggest the cattle outbreak is "much larger than originally thought."

To better understand the scope of H5N1's spread among cattle, increased testing of dairy cows is now a key facet of the American response.

The U.S.will require dairy cattle moving between states for commerce to be tested for bird flu, Secretary of Agriculture Tom Vilsack told reporters this week. All labs and states must also report positive tests for any form of influenza.

The concern from both officials and scientists alike stems from the potential impacts on animal health and the food supply chain, and the possibility that this virus is inching closer to a pandemic-level threat to humans as well.While the reported cattle infections haven't been serious, scientists warn they could fuel adaptations that could make it easier to infect more mammals.

Since 2022, only two human infections have been reported in the U.S., with the latest one tied to these recent cattle outbreaks. Both were mild. But sporadic human cases linked to contact with infected animals in previous outbreaks have been happening around the world, with many causing serious symptoms, severe pneumonia, or even death.

Based on available human case data to date, the death rate of this form of bird flu is thought to be a staggering 52 per cent, though scientists say there are likely far more mild cases going underreported and skewing that data.

Even so, with so many cattle being infected and coming into contact with farm workers every day, the number of human exposures is going up, Worobey warned. "It's kind of like buying more and more lottery tickets in the lottery of, 'Can a new pandemic virus actually evolve?'"

Infectious disease physicians in Canada are keeping a close eye on the places where livestock, wildlife and humans intersect.

Officials at the Canadian Food Inspection Agency have not yet responded to a series of questions fromCBC News, but said online it has not detected this type of avian influenza in Canadian cattle, so it's not currently testing raw or pasteurized milk.

"[Highly pathogenic avian influenza] is not a food safety concern as pasteurization kills harmful bacteria and viruses," the agency said on X, formerly Twitter.

Dr. Samira Mubareka, a clinician scientist at Sunnybrook Research Institute and the University of Toronto, is watching for any signs of the virus becoming more adept at transmitting between mammals, including humans.

"From the virus's perspective, the more transmission there is, the more opportunities to adapt," Mubareka said. "That is concerning."

Mubareka said any enhanced change in transmission among mammals would also signal an enhanced ability to transmit among humans, which is why it's so important to find out whether those in close contact with cattle or wildlife are at higher risk.

She said even if this H5N1 virus doesn't infect more people, the virus has already hit animal health significantly and could affect food prices, food security and livelihoods.

Rasmussen agreed, and said the impacts could be grim if human-to-human transmission begins.

"It would have a devastating impact on human and animal health, on the economy, on the food supply," she said. "It would be a worst case scenario."

Lauren Pelley Senior Health & Medical Reporter

Lauren Pelley covers health and medical science for CBC News, including the global spread of infectious diseases, Canadian health policy, pandemic preparedness, and the crucial intersection between human health and climate change. Two-time RNAO Media Award winner for in-depth health reporting in 2020 and 2022. Contact her at: lauren.pelley@cbc.ca

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Why dangerous bird flu is spreading faster and farther than first thought in U.S. cattle - CBC.ca