Virus World

With egg prices in the United States soaring because of the spread of H5N1 influenza virus among poultry, the U.S. Department of Agriculture (USDA) yesterday conditionally approved a vaccine to protect the birds. President Donald Trump’s administration may therefore soon face a fraught decision on whether to join the ranks of other nations—including China, France, Egypt, and Mexico—that vaccinate poultry against H5N1. Although many influenza researchers contend that vaccination can help control spread of the deadly virus, the U.S. government has long resisted allowing its use because of politics and trade concerns that many contend are unscientific. The USDA approval may signal a shift in policy linked to the Trump administration’s worries about egg prices. Even with the conditional approval, USDA must still approve its use before farmers can start to administer the vaccine because special regulations apply to H5N1 and other so-called highly pathogenic avian influenza (HPAI) viruses. The vaccine, made by Zoetis, contains a killed version of an H5N2 variant that the company has designed to work against circulating variants of the H5N1 virus that have decimated poultry flocks and have even jumped to cows and some humans. (The “H” in both variants stands for hemagglutinin, the surface protein of the virus, and antibodies against it are the main mechanism of vaccine-induced protection.)

Researchers at the U.S. Centers for Disease Control and Prevention reported yesterday that three cow veterinarians harbored antibodies to the H5N1 virus in dairy cattle. None had symptomatic disease, they noted in the Morbidity and Mortality Weekly Report, suggesting the virus may be more widespread in humans than previously thought. Zoetis CEO Kristin Peck announced the approval yesterday on CNBC. “The decision to vaccinate commercial poultry flocks rests solely with national regulatory authorities in consultation with their local poultry sector,” said Zoetis in a statement, which noted it has approval for similar vaccines in other countries. Zoetis also had an earlier version approved in 2016 that was in the National Veterinary Stockpile until 2021, but it was never used. HPAI strains such as the current H5N1 have for decades been stamped out largely by culling affected flocks and enforcing strict biosecurity measures. But that strategy has failed since the February 2022 emergence in the U.S. of an H5N1 virus that belongs to a lineage known as clade 2.3.4.4b. Many scientists now worry the virus cannot be eradicated from the U.S. poultry flock, which means it has become endemic rather than epidemic. “The future of H5 in the Americas isn’t entirely clear, but endemicity looks likely,” says Richard Webby, a bird flu investigator at St. Jude Children’s Research Hospital. “Updated and quality H5 vaccines for poultry must be a big part of future responses if this is indeed the case.”

New Zealand has ceased all poultry exports from its commercial rural Otago egg farm, after tests confirmed a “high pathogenic” strain of avian influenza in chickens. Notably, the viral strain differs from those responsible for the recent H5N1 (US) and H7 outbreaks in the US and Australia, respectively, confirms Biosecurity New Zealand. The move is expected to halt the exports of poultry products worth about NZ$190 million (US$112 million) a year until the country announces it is free of bird flu, according to Food Safety Minister Andrew Hoggard. Tests from the Mainland Poultry managed farm identified the bird flu strain as the H7N6 subtype of avian influenza, which is closely related to low pathogenicity (HPA1) strains present in wild birds in the country. The outbreak may be a “spillover event,” where laying hens who were foraging outside of the shed were exposed to a low pathogenic virus from wild waterfowl,” explains Stuart Anderson, deputy director-general of Biosecurity New Zealand. “Low pathogenic viruses are present in wild birds here, especially waterfowl like ducks, geese, and swans, and the virus can mutate on interaction with chickens.” Amid ongoing human transmission concerns in other bird flu cases, especially farmers, Anderson assures that the strain found on the New Zealand farm is “not a wildlife-adapted strain like H5N1, so we believe it is unlikely to be transmitted to mammals.”

Ensuring food safety

According to Biosecurity New Zealand, there are no reports of ill or dead birds on other poultry farms and “no human health or food safety concerns.” It suggests consuming “thoroughly cooked” egg and poultry products by heating food to an internal temperature of 75°C for at least 30 seconds, or 70°C for three minutes or 65°C for 15 minutes.

Government action

The government is taking “quick action” along with Mainland Poultry and has issued a restricted place notice. “Test results late last night confirmed the strain, but we already had restrictions in place and expert biosecurity staff on site, with more arriving today.  Mainland Poultry took the right steps by reporting ill birds in one shed on the property and locking that building down as testing continued,” says Anderdon. Biosecurity New Zealand has placed a 10 km buffer zone around the farm, with restrictions preventing animal movement, equipment and feed movement. John McKay, chief executive of Mainland Poultry, which manages the free-range farm, says international experience with avian influenza has proven that H7N6 can be eradicated “quickly and successfully.” “We will be working closely with MPI (Ministry for Primary Industries) to depopulate the affected shed, ensure rigorous testing of all other birds on the farm and manage the situation effectively.” The farm has strong biosecurity standards and Mainland is helping the MPI with ongoing investigation and tracing animal movements. It suggests farmers to contact a veterinarian if they notice poultry or domestic birds exhibiting signs of HPAI, to rule out more common avian diseases. All content and features on this website are copyrighted with all rights reserved. The full details can be found in our privacy statement

Experts warn that lax regulations could also see the virus spread to US pig farms, with serious consequences for human health. Fears are growing that the H5N1 outbreak among cattle in the United States could have been caused by contaminated animal feed.  In contrast to Britain and Europe, American farmers are still allowed to feed cattle and other farm animals ground-up waste from other animals including birds. Dairy cows across six US states – and at least one farm worker – have become infected with the highly pathogenic virus, which has already killed millions of animals across the globe since 2021. The farm worker, who is thought to have been exposed via infected cattle in Texas, is only the second recorded human H5N1 case in the US. Since February, the US has investigated and discounted a further 8,000 possible exposures, according to Dr Joshua Mott, WHO senior advisor on influenza.  The development is of concern because it allows the virus, which has killed millions of birds and wild mammals around the world, more opportunities to mutate...

The emergence and global spread of the highly pathogenic H5N8 avian influenza virus (AIV), a pathogen that has caused continuous and ongoing outbreaks with massive mortality in both wild and farmed birds across Eurasia and Africa throughout 2020, represents a considerable public health concern — particularly considering the first human cases of H5N8 infection were first reported last December. In a Perspective, Weifeng Shi and George Gao discuss the emergence and zoonotic potential of the H5 AIV lineages. Shi and Gao argue that vigilant surveillance and rigorous infection control measures for these emerging viruses are critical to avoid further human spillovers that could result in new and devastating pandemics.

Perhaps overshadowed by the ongoing global COVID-19 pandemic, over the past year, H5N8 infections in both wildfowl and poultry have been identified in at least 46 countries across Europe, Asia, and Africa. While these outbreaks have led to the death or slaughter of many millions of birds worldwide, they’ve also notably resulted in at least one spillover event in Russia, where seven poultry farm workers tested positive for H5N8 virus. According to the authors, the rapid global spread of this AIV and its demonstrated ability to cross the species barrier, transmitting to humans, makes it a major concern to not only farming and wildlife security, but also global public health. Shi and Gao suggest that the surveillance of highly pathogenic AIVs in poultry farms, live markets, and wild birds must become a global priority.

Cited publication available in Science (May 21, 2021):

https://doi.org/10.1126/science.abg6302

Rose Acre Farms, the nation's second largest egg producer, said yesterday that tests have confirmed avian flu at its facility in Seymour, Indiana, which could further stretch the supply of eggs as commercial farms in several states continue to battle the spread of the H5N1 virus. In other developments, the US Department of Agriculture (USDA) reported more H5N1 detections in mammals, poultry, dairy cows, and wild birds, and European health groups issued a guide for assessing avian flu mutations that may pose a risk to humans.

Layer farms hard hit in poultry outbreaks

The company said on X that it first noticed mortality in the layers on January 25 and quickly sent samples for testing. Rose Acre Farms has operations across the country. The Seymour, Indiana, facility is located in Jackson County. The Indiana Board of Animal Health of Animal Health on January 26 announced that the virus had been detected at a layer farm in Jackson County that has 2.8 million birds. The company said it tightened its already rigorous biosecurity measures, is working with state officials, and is monitoring its other facilities. Since the first of the year, outbreaks at layer farms have led to the loss of at least 13 million birds.

An avian influenza outbreak in Victoria prompts the US Department of Agriculture to ban all poultry products until further notice.

In short: An outbreak of avian influenza in Victoria has prompted the US to ban all Victorian poultry products. The restrictions apply to fresh poultry, commercial birds, eggs and poultry by-products. What's next? In an effort to contain the outbreak, Agriculture Victoria has placed the two farms impacted by the outbreak in a control zone. The United States Department of Agriculture has banned imports of all Victorian poultry products following an avian influenza outbreak. The H7N3 strain of the virus commonly known as bird flu was found on an egg farm in Meredith, west of Melbourne, on Wednesday and has since been linked to another site 130 kilometres south-west in Terang. The two properties share joint management, staff and machinery. More than 500,000 birds have had to be euthanased this week. The H7N3 is a high pathogenic strain of avian influenza and resulted in 400,000 chicken deaths at the Meredith farm in a bid to control the spread of the virus...

More than 20 states have reported avian influenza in commercial and backyard farms.  A growing epidemic of bird flu across the East Coast and Midwest has led to more than 20 million birds dying or being destroyed since February, fueling a surge in egg and poultry prices. After circulating for months in Asia and Europe, highly pathogenic avian influenza (HPAI) has been detected in commercial and backyard farms in more than 20 states, according to the US Department of Agriculture. Individual farmers have been forced to cull hundreds of thousands -- sometimes millions -- of birds to check the spread of the disease.  Shell egg prices have jumped to $2.88 a dozen (up more than 50%) since Feb. 8, when the first case was identified in a commercial turkey flock in Indiana. No humans have tested positive in the US yet, but the economic toll could be major: The first US epidemic in 2015 cost the poultry industry more than $1.5 billion and caused egg prices to nearly double. Here's what you need to know about bird flu, including what the outbreak means for consumers, how the industry is combating it and if it poses a threat to humans.

What is bird flu?

Bird flu is caused by avian influenza Type A viruses, which spread naturally among waterfowl and can infect wild birds, domestic poultry and other animals, though rarely humans. There are more than a dozen strains of bird flu, which are classified as either "low pathogenic" or "highly pathogenic," depending on their ability to spread disease and kill poultry.   The strain bombarding the US right now, Eurasian H5N1, is considered highly pathogenic.

How is bird flu transmitted?

The main source of infection is migratory waterfowl, such as ducks and geese. "They get infected but don't get sick," Denise Derrer, public information director for the Indiana State Board of Animal Health, told CNET. "Then they shed the virus in their droppings or wherever the land." That means the spread could peak in a few weeks, when spring migration reaches its high point, and not abate until June, when the birds settle into their summer breeding grounds. How the virus gets from barn to barn is still not entirely clear, which makes it hard to get a grip on the situation, according to Dr. Yuko Sato, a professor at Iowa State's school of veterinary medicine. "There's no concluded study on how it's coming in," Sato told NPR. "We can identify some weak links -- for example, people tracking it in." 

Where have bird flu outbreaks been detected?

The current strain of H5N1 was first reported in Asia and Europe. In the UK, eggs can no longer be labeled free-range because hens have been cooped up for months to avoid infection. Since the USDA confirmed the first US case in a wild duck in South Carolina in mid-January, infections have been reported in commercial farms and backyard flocks in Connecticut, Delaware, Illinois, Indiana, Iowa, Kansas, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, North Carolina, North Dakota, New Hampshire, New York, Ohio, South Dakota, Wisconsin and Wyoming.  As a result, more than 20 million egg-laying hens, poultry chickens and turkeys have been or will soon be "depopulated," or killed, with more infections detected nearly every day. On March 31 alone, infections were detected in five states.

Among the worst outbreaks: