A discussion of the situation involving H5N1 (avian influenza/bird flu) and dairy cattle with UNL’s BeefWatch Podcast host Aaron Berger, beef Extension educator and Dr. Matt Hille, an assistant professor and diagnostic pathologist at the Nebraska Veterinary Diagnostic Center based on the campus of the University of Nebraska—Lincoln.

Question

Dr. Hille, lay the groundwork for us a little bit about the H5N1 virus and this recent development where it's been identified in some dairy cattle.

Answer

I would start probably in in late February, early March. There were some rumblings about some dairy cattle in the Panhandle of Texas that were presenting with an otherwise unexplained drop in milk production. There was some chatter about some of these cows getting a little sick, if you will, but really the drop in milk was the main thing that most people noted. So we had about 2 or 3 weeks there where that's pretty much all anybody knew.

And then on March 25th, the National Veterinary Services Lab in Ames confirmed the presence of an H5N1 highly pathogenic avian influenza virus in milk samples from some of these cows that were affected with that. So that kinda got us to the diagnosis, the presumed etiology or the cause in that case. And since then, it's been detected in, I believe, the latest count is 36 premises across 9 states. And like you mentioned, we have not had a confirmed case as of today, in the state of Nebraska. 

Question

So this is a novel situation because to my knowledge, this has not been identified in cattle before. Help us understand what may have occurred that triggered this new situation.

Answer

It's tough to say for certain, but it's well known that influenza viruses can—to kind of simplify— they can change their makeup. So that can make them more or less susceptible to certain species. And there's potential that that could be what has gone on in this case to make cattle, who are historically not a traditional host of avian influenza viruses, start presenting with cases.

Question

So what do we know today in terms of how this virus is spread as we think about dairy cattle and then spreading it to other cows in the herd, and then what are some risks we need to be aware of with that? 

Answer

There’s evidence to suggest cow-to-cow transmission, what we often refer to as lateral transmission. So milk is assumed to be the most likely source of any transmission mainly because the milk has by far the highest viral load of the tissues that have been tested. There also have been confirmed documented cases of spread from dairy back into poultry with the specific dairy strains, if you will, of this virus. So that's one important point, particularly for dairy men to be aware of, that HPAI, highly pathogenic avian influenza, it's not just a poultry thing, it's not just a dairy thing. We have evidence of that going back and forth, since this initial diagnosis on March 25th. 

So one important point to think about with that is particularly for workers, if you have workers who are working part time in a dairy that may be working also in or around poultry that would be something to be aware of.

Question

To date, there's only been one case identified where a worker in a dairy where this virus was present then contracted it themselves. That's the only one I'm aware of in terms of a human impact from the virus. Is that correct?

Answer

Yes. My understanding is the same. It was one dairy worker in Texas who presented with conjunctivitis, which is inflammation, in around the eye. And my understanding is that person was treated with antivirals and recovered.

Question

So that is our only confirmed case, in a human. You mentioned there are some biosecurity issues that folks need to be aware of, and there have been some changes in terms of transport of dairy cattle and requirements now that have not been in place in the past. Tell us a little more about that and what's being done there.

Answer

Important  things for producers to be aware of, I think, at least as of today is that things can certainly change. But the Nebraska Department of Ag has extended, effective, I think, May 1st, through through May 31^st, an importation order, which means that any breeding female dairy cattle that enter the state need to obtain a permit prior to that entry.

And then last week, USDA APHIS issued a federal order that that went into effect Monday, April 29th that requires any interstate (between states) movement of lactating dairy cattle to have documentation of a negative Influenza A PCR test within the prior 7 days before they're allowed to move between states. The Nebraska Veterinary Diagnostic Center, the lab that I work at, is an authorized lab for that testing, and we're prepared to do that testing as needed by the industry for interstate movement of lactating dairy cattle. That's all that that order currently covers is just lactating dairy cattle.

So in that context, you know, it's important for anybody, particularly if there's interest or requirements on their own operation to move lactating dairy cows, to work with their local veterinarian, to be sure that all these boxes are checked essentially and to stay up to date on that information so that they are able to efficiently move these cows with hopefully fewer hiccups by knowing the requirements that need to be met.

Question

One of the things you mentioned is that it appears that milk from a cow that has been infected with this virus is a very high source of the virus. What are some things to be aware of with that? And then as we think about milk that enters the food chain, what are some things to know there as well?

Answer

Of the different tissues tested, milk seems to have by far the highest viral load in these cows that are affected. So there are some precautions with that. We talked about there's only one confirmed human case, but we do have precedents in the past with other Influenza A viruses, making that jump to humans. So what I've been telling people and I think is accurate is that the risk to humans from raw milk seems to be very low, but it's not 0. So if someone finds himself handling large amounts of raw milk, i.e. working in the parlor—taking normal precautions such as gloves, routine handwashing, potentially a face shield if they're so inclined— taking these kind of basic precautions would be advisable, given that milk seems to be the highest viral load.

In terms of the milk products, though, there's nothing to suggest that any pasteurized or treated milk or dairy product are anything but safe. Frankly, it's the reason we do things like pasteurization, to eliminate the viability of these pathogens.

That speaks to a release that went I think it was last week. Some of the listeners may have seen the release about finding, “fragments of virus” in retail milk. Frankly, that's not surprising at all given the testing they used, which was PCR. All that does is look for and tell you if there's genetic material there from whatever pathogen you're looking for. It's not surprising that they found it in milk because that's where we see it in these cows. But again, treated milk, pasteurized milk, will render that virus nonviable and is completely safe.

Question

The next question that comes to mind for me then is what about muscle tissue from these dairy cows? Obviously dairy cattle are a source of beef for the United States and what happens with those cows? Is there a risk there?

Answer

So that's a timely question. Yesterday USDA released some initial results from a study where they're they were looking at retail beef from what they said was 30 locations near positive dairies. Personally, there's a little bit of confusion on my part there because they don't state whether these were definitely dairy cows or not, but those are the results that they put out.

Long story short, there was no virus detected in any of those raw beef samples at the retail level, and that's not surprising. Again, milk is where we would expect to find the highest viral load. So even to find it in any sort of meat, that animal would have to be viremic. And, again, along the lines of pasteurization, there's a reason we cook our raw meat products as well for the same reason.

Question

So what I hear you saying is how we think about milk going through the pasteurization process, meat going through an appropriate cooking process should also render those viruses inoperable.

Answer

Absolutely. And really, in my opinion, nothing has changed given this virus that would change any sort of our normal raw meat handling, cooking, or pasteurization processes. This is just a good example of why those processes are in place in the first place. So yes, there is no reason to say that these products are anything but safe.

Question

From a beef cattle perspective, what are some things producers may be wanting to pay attention to as we look at the current environment right now with this virus being present in dairy cattle?

Answer

For  beef producers specifically, I think a lot of it's just to be aware of this situation and to keep a finger on the pulse of the of the information as we get it and it unfolds.Again, we have no confirmed cases of the H5N1in Nebraska, in dairy or beef for that matter, and we're just simply not seeing these issues in beef cattle from H5N1.

That’s not to say they're completely immune, but even if we assume some are becoming affected or infected, it certainly doesn't appear to have any meaningful impact on the industry. We're just not seeing the cases. Anything out of the norm in the field or in our diagnostic submissions from beef cattle that come here to the Veterinary Diagnostic Center.

Question

Dr. Hille, this does bring up, as we think about these dairy cows that have been infected, they obviously have recovered. Are they going to carry some immunity now, and what does that look like?

Answer

That's a good question. There’s some serologic testing that's recently been ironed out. It would be likely that there would be some long-term immunity after these cows were to seroconvert and recover. But we really just don't know, at this point how long that will be, how robust that would be in these cows.

Question

Well, anything else on this topic you'd like to highlight today that you think would be valuable?

Answer

I would like to take a minute to point out for listeners interested, we've tried to do routine updates on the UNL Dairy Extension website. So the way I've tried to do that was essentially, even if you know nothing about this subject, you could go there. I started on April 17th with a longer document, and that's a date stamped document.

So the April 17th document essentially starts at the beginning and walks through essentially what we knew on April 17th of this situation. And then I've updated posted updated documents as new information comes out that would be, I think, pertinent to dairymen in particular, but really to any interested stakeholders or livestock producers at all. There are Spanish versions of that, and there's also an audio recording where I sat down and went through that document. I think it's about 20 or 25 minutes, in a little bit more in-depth where I could expand on some of the points I made in the document. And there's also a Spanish version of that audio recording available.

We’ll continue to post updates as new information comes out, as people would probably expect. Over the last 2 to 3 weeks, there's been a lot of new information almost daily on this subject. So anybody interested can go to dairy.unl.edu to stay up on that information. And then in terms of biosecurity, when it comes to this this virus, we have posted a biosecurity risk assessment on the Big Red Biosecurity website. So that's bigredbiosecurity.unl.edu.

It's linked with the dairy site as well. So if you go to the dairy site, there's links to take you there. That is a document that is freely available for download. You can just download it from home. It's geared toward dairymen, but, really, a lot of the principles would apply to any sort of livestock production setting.

It is essentially a list of general biosecurity principles that a farmer or rancher could look at and check the box like a survey. “Yes. I do this.”  “This could be improved, or this is not applicable to my to my farm or ranch.”

And the goal with that is to simply, potentially get people thinking about ways they might be able to improve their own biosecurity to minimize the introduction of any infectious disease, but specifically with this document, H5N1, into dairies.

Question

Doctor Hille, I really appreciate your time today and for bringing us up to speed on your knowledge of the virus currently. Obviously, the situation changes frequently as you already mentioned. And so dairy.unl.edu appears to be the best place to go to get a current update. Is that correct?

Answer

Yes. That's where I would encourage anyone to go for more questions, and they can reach out to me directly as well. My all my contact information is on that Dairy Extension website and those all those documents.