Nearly one year ago, USDA made a shocking announcement. Highly pathogenic avian influenza type A H5N1 (H5N1) was identified in milk and in cows on two dairy farms in Texas and two dairy farms in Kansas. A disease no veterinarian had previously feared in cattle had jumped from wild birds to domestic cows.
Scanlon Daniels, a large animal veterinarian with Circle H Headquarters in Dalhart, Texas, received a call 10 days prior to that announcement that he will never forget from one of his dairy clients that something wasn’t right with some of the cows.
“My client sent me a text: ‘I think I might have it,’” Daniels says.
He went out to the dairy, collected samples from four cows and submitted them to Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) as any good swine vet would do, he explained, during the American Association of Swine Veterinarians annual meeting. He also took some nasal swabs and tested those in his own lab. He did a follow-up, collecting samples from 20 different cows later on that week and sent those to the Iowa State University Veterinary Diagnostic Lab.
The four cows that initially presented symptoms of decreased rumination, decreased activity and nasal discharge were eventually confirmed to have H5N1. Right around that same time, he said there were reports from Texas Animal Health Commission about a backyard poultry flock in the county next door diagnosed with H5N1.
“We had a suspicion that it could have been influenza, because of what was going on with some of the detections in birds in that area,” Daniels says. “But from my standpoint, I was thinking about flu from all my experiences dealing with it in pigs, and it didn’t present as a primary respiratory pathogen. It presented as a mastitis pathogen. Once we knew to look for it in milk, it was super easy to find, but we had to get over that hurdle to be able to rapidly identify it.”
In the past 15 years, Daniels grew his practice to develop its own laboratory capabilities, conducting PCR and Elisa testing for swine, dairy and beef clients. This, combined with his involvement with H5N1 from before it was even identified as an issue in cattle, caused him to bring up an incredibly important question for the swine industry: Are you ready for H5N1?
Who is Steering the Ship?
To date, H5N1 has been discovered in one pig that was on a hobby farm with H5N1-infected poultry. Although this is considered an isolated incident and hasn’t been discovered in the commercial swine population, it needs to be on everyone’s radar, Daniels says.
Andrew Bowman, DVM, one of the country’s top swine influenza experts, joined The PORK Podcast during a special report on H5N1 last fall. A professor in the Department of Veterinary Preventive Medicine at The Ohio State University, he is well-known for his expertise in swine production medicine, veterinary public health and epidemiology.
“Across the swine industry, we routinely deal with influenza, so we’re pretty well versed in flu,” Bowman says. “But this adds a whole other character to the scene that we really don’t want reassorting with the flu viruses we already have.”
One of the things that makes H5N1 different than other new swine disease outbreaks is that the USDA has jurisdiction over H5 in any animal, so they have the regulatory authority, Daniels says.
“USDA had no rules or regulations around H5 in cattle, and we’re at the same place today in the swine industry,” Daniels adds. “If we were to find H5 in swine, USDA would have the authority and there are no rules or regulations around it.”
This has made the discovery of H5N1 in dairy cattle challenging in the past year, because it’s taken a long time for those regulations to be developed.
“There’s the state and federal aspect of that, where states have autonomy to set their own rules, and then federal rules can come in place that everybody has to abide by,” he points out. “There’s been this slowly evolving plan with a patchwork of regulations by different states. That’s been challenging to keep up with as a veterinarian and a producer.”
The recent COVID-19 pandemic has likely amplified concerns around influenza’s ability to be transmitted from humans to animals and from animals to humans.
People are fearful of government influence and interaction, he says.
“No one wanted to be first or second or third to get H5N1 in their dairy cattle – just like no one wanted to be first to get COVID-19. There was a reluctance to test because of the uncertainty of it,” Daniels explains. “People fear government overreach or regulations that wouldn’t be applied in a fair or equal way across the industry.”
The Stakes are High
Everybody has a stake in this issue, Daniels says. The challenge is that everybody comes to it with differing priorities regarding the issues at hand.
The American Association of Bovine Practitioners invited seven different groups that have the ability to provide vaccine to share about their technologies on a webinar. This gave avian and bovine veterinarians alike exposure to their vaccine technology.
“The hard part is getting everybody to agree on what needs to happen,” Daniels says.
But he believes the vaccine question is worth talking about.
“If it was just another influenza, we would have had a vaccine available in a couple weeks, honestly,” he says. “The government has the ability to authorize vaccine use under an emergency use exemption. For all the concerns that have been talked about with export markets, and how people might respond from a trade standpoint, they haven’t been willing to look at that. But if we could use vaccine on an experimental use basis, we would know a lot more by now about the value of that intervention.”
In a USDA update on March 20, Secretary of Agriculture Brooke Rollins said USDA is exploring the viability of vaccinating poultry for highly pathogenic avian influenza. However, Rollins said the use of any vaccine for poultry or any animal species has not been authorized at this time.
“I know there has been some misreporting on that,” Rollins said. “The day we rolled out the plan, I actually talked about the fact that we’re not ready to vaccinate. We need to do some more research, and so that has not changed, but I do look forward to this next process of learning more about getting more research done and perhaps seeing what makes sense for the country moving forward, once that is concluded.”
Another concern on Daniels’ mind is the implication with human health. Influenza A viruses are common in people. They are constantly changing and reassorting.
“Influenza viruses exist and circulate in people all the time,” says National Pork Board chief veterinarian Dusty Oedekoven. “The threat of influenza virus infection is ever present. It’s why healthcare providers recommend people get annual influenza vaccines to prevent against new strains of the virus that are emerging all the time.”
Daniels says the unknown transmission opportunities between humans and animals, especially pigs, can be concerning.
At a recent bovine practitioners meeting, they surveyed 150 veterinarians and found three of them have had prior exposure to H5N1, he says. Some of those had no contact with dairy or birds.
“It would probably be wise for us to do some serosurveillance to know if people working at hog farms have had some exposure and it hasn’t transmitted yet,” he points out.
For example, his lab had a lot of infected milk come through before they knew what it was.
“My staff had legitimate fears and concerns we had to address,” Daniels says. “Fortunately, we didn’t experience any illness or lost time outside of the normal. That could have been different. We can’t lose sight of the human aspect of it. I am a human, a swine vet and a beef producer, so I can understand several aspects of it from a balanced way.”
Hurdle By Hurdle
At the end of the day, the swine industry has a lot to learn from what the dairy industry experienced in the past year, he says.
“On one hand, we have advantages relative to bovine veterinarians because we have a strong background and applied experience in diagnostics and strong working relationships with state and federal animal health officials,” Daniels says. “We have a mindset of disease elimination when possible and strong integrated relationships with producers. The swine industry also has the ability to direct Pork Checkoff dollars toward research (the dairy industry does not).”
On the other hand, he says many of the factors that have caused consternation will continue to be problematic if HPAI is identified in swine. Studies need to be done looking at H5N1 in swine, he says. If a sow is infected, does it transmit to pigs? Can her pigs shed it to contact controls? How could the movement of wean pigs spread the disease?
He also wonders if pigs have some cross-protective immunity at this point because influenza is pretty much endemic in almost all swine populations. And, even though it presents in the mammary system in cows, he argues the swine industry could do some additional work in growing pigs, because it would be easier to deal with there than on a sow farm.
One of the biggest hurdles is that H5N1 is a select agent. Once samples are known to be positive for H5N1 antigen, there are many requirements related to storage, handling and testing that come into play. Space is limited to research H5N1 and Daniels is concerned at the delay in testing this virus in swine.
For comparison, the relative economic impact of H5N1 in dairy is estimated to be approximately 10% that of a porcine epidemic diarrhea virus (PEDV) outbreak in swine, he says.
“We have seen growing interest by veterinarians and producers in eliminating H1 and H3 influenza infections in swine, but the interest and adoption is less than what we see for porcine reproductive and respiratory syndrome and PEDV,” Daniels says. “Would we see the same if H5N1 was identified in swine?”
He believes the swine industry still has an opportunity to develop the response to H5N1 in commercial swine before it occurs.
“It’s time to get some of these questions answered that are important to us,” Daniels says. “If it were to happen, we need to be prepared to address some of the risk factors, things that are real versus the fear of the unknown.”
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Editor’s Note: On March 12, APHIS confirmed the presence of highly pathogenic avian influenza H7N9 in a broiler chicken breeder flock in Mississippi. APHIS has previously documented H7 low pathogenicity avian influenza in U.S. wild bird surveillance this year and in previous years, but this is the first HPAI H7 case in commercial poultry in the U.S. since 2017. This H7N9 virus is a fully North American virus of wild bird-origin and is unrelated to the Eurasian H5N1 currently circulating in the U.S. Spillovers of avian influenza from wild bird sources can occur due to breaches in biosecurity. APHIS closely monitors these subtypes because H5 and H7 LPAI viruses in poultry species such as chickens and turkeys can mutate into highly pathogenic avian influenza.
