Episode 217 - Diagnostic sampling, transmission, biosecurity, and Koch's Postulates
Hey, everybody. Quick announcement, housekeeping things at the beginning of this episode. Because of of the situation where cattle have tested positive for high path avian influenza in Texas and Kansas, the monitoring of that situation, I am going to put out an episode when I have more information. For now, we may or we may not get to getting out our normal Monday 5 AM episodes. So I apologize.
Dr. Joe Armstrong:But you're getting probably more content now because I'll be putting out more episodes overall. They just are gonna come out on a weird schedule. Thank you for understanding. Thank you for listening. Hang in there, everybody.
Dr. Joe Armstrong:What is up, everybody? This is doctor Joe Armstrong. It is approximately 9 PM on March 28th. Why is it this late when I'm recording? Well, you'd think, oh, I'm waiting to no.
Dr. Joe Armstrong:I'm not waiting for anything or doing anything real fancy. I got sick kids at home, and this is when stuff like this happens sometimes. But the date and the time are important because it tells you where we are in the progress of what we're looking at with the situation concerning high path avian influenza in dairy cattle. If you haven't listened to the previous episode, I encourage you to do so. That'll keep you up to date on where we are in the process.
Dr. Joe Armstrong:This whole thing starts in Episode 2 16 as we get our official first announcement from USDA, APHIS, telling us that cattle have tested positive for high path avian influenza in Texas and Kansas on dairy farms. We are waiting on more information. That's where we're at. I I really thought we would have more information before the end of this week. I don't expect anything coming out tomorrow, which is Friday before Easter, but you never know.
Dr. Joe Armstrong:That is a possibility. They might release it. They might not. I don't personally expect anything till next week, but we will see. So why am I on tonight, and why am I taking the time to record?
Dr. Joe Armstrong:It's not to tell you nothing. I promise. We're getting quite a few questions, and there's some repeats. Definitely some repeats. I wanna go through the answers to those questions because I'm getting them a lot, and I want people to know what we are thinking about it at this situation and what we should be doing.
Dr. Joe Armstrong:1st big common question is, hey. I got this situation. What samples do I need? So if you have a case profile of a herd that fits, a lot of veterinarians are asking, what samples do I need and what should I be collecting? That's an important question to know the answer to.
Dr. Joe Armstrong:And I'm expecting there to be a diagnostic guide coming out from USDA or AABP at some point. It's not out yet. So I'm going to tell you what I've heard. What I've been told is what we need to collect. So, the positive samples have been tested so far have been milk and nasal swabs.
Dr. Joe Armstrong:That is not the only samples we need. We need more than that because more data is better. We need to figure out all aspects of this problem, and that only happens when we get a full diagnostic picture. That means what we need is not only milk, 25 milliliters of milk, we need whole blood, we need serum, We need urine, feces. Those are the things we need.
Dr. Joe Armstrong:In the ideal scenario, what we need is those samples from both affected and nonaffected animals and preferably 10 of each minimum. We can't go crazy sending all sorts of samples. We can't we don't have unlimited amounts of money to fund this testing. There is money to fund testing for samples that fit the case profile. So, there's not money right now to conduct any surveillance or anything like that.
Dr. Joe Armstrong:There potentially is money in the diagnostic labs that are a part of a national network, the National Animal Health Laboratory Network, for samples that fit the case profile. The best thing to do if you are in any question is to contact your state animal health official or the diagnostic lab directly. They're doing an excellent job at the diagnostic labs, getting everyone on the same page. So, you should be able to call, get a hold of this information quickly. But as a review, what we need, 25 ml of milk.
Dr. Joe Armstrong:After that, we need whole blood, serum, urine, and feces from 10 affected and 10 non affected animals. Producers, farmers, if you're listening to this, you got to lean on your veterinarian for this kind of thing. If you know what you need, they can help you get it. Alright. Other questions that are coming in that we need to figure out.
Dr. Joe Armstrong:What about this goat that tested positive in Minnesota in Stevens County? That's a legitimate question. We got high path avian influenza confirmed for the first time in any ruminant in Minnesota in Stevens County. How is that connected, if at all, to these positive high path avian influenza cases in Texas and Kansas? Now, that's a question I cannot answer at this time.
Dr. Joe Armstrong:What's going to help us with that answer, give us more information, is when we get more information about the specific strain that's going through Texas and Kansas. That's going to depend on sequencing. So, once we have that information and they have sequenced everything with the goat, we can compare the 2 and see how close, if they are related at all. But at this time, we don't have that information, so I can't answer it. We'll come back to that as soon as we know.
Dr. Joe Armstrong:Now, we're getting a lot of questions about transmission. And that's, again, a question that we don't have all the answers to right now. USDA very confident in saying that most likely the source is wild birds. Now, there's 2 questions that have been coming in. How is it getting from birds to cattle?
Dr. Joe Armstrong:That's the first question. We'll answer that. I think it's most likely and very, very possible that we have contaminated feed and water from wild bird populations, and that is how it's getting into these herds. When we think about the types of birds that are usually the hosts of this avian influenza, we're talking mostly about waterfowl, migratory waterfowl. So when you think about those species and we think about how much comes out the back end, I don't think it's unlikely at all that we could have contamination in water and feed.
Dr. Joe Armstrong:Now, the second question about transmission is one that we cannot answer fully right now. So there's a couple different forms of this question that I've gotten. There are popular press articles out. There are reports from other sources other than USDA that have said it does not appear to be transferring from cow to cow at this time. And people are asking, how could they possibly know that?
Dr. Joe Armstrong:The first thing I want to point out about that question is USDA, AAFIS, did not ever say that in their press release. There is nowhere in that press release where they say that they have evidence that it is not transferring from cow to cow. The only thing that is even remotely close to that in USDA APHIS's release is that the National Veterinary Services Laboratory has not found changes to the virus that would make it more transmissible to humans, which would indicate that the current risk to the public remains low. That is the closest thing. There is nowhere in that press release where it says anything about having evidence that it's not transferring from cow to cow.
Dr. Joe Armstrong:Now there's always people behind the scenes that know more about situations like this than the public. Always. And they're always days ahead of where the announcements are. But everyone has to be incredibly careful because there's a lot at stake here, and we need to get the facts right. And getting the facts right involves a ton of confirmatory testing.
Dr. Joe Armstrong:So to answer the question, is this transferring between caps? I don't have enough information to give an answer to that question right now. I will say, in my personal opinion, make sure you hear that, my personal opinion, I would be very surprised if it is not transferring between cows. But at this time, I cannot confirm what is happening with transmission between cows. We will wait, and we will see what we get from USDA after we have more information about sequencing and a little more epidemiology about what's going on.
Dr. Joe Armstrong:Vague, wishy washy, whatever you wanna call it. That's where we're at right now. When we talk biosecurity did this a little bit in the last episode. But when we talk specifics of biosecurity, the basics come back. We need to know who's on the farm.
Dr. Joe Armstrong:I would advise that we probably limit who's on the farm right now while we're still figuring out what's going on. Quarantining animals is a good idea. Is it possible all the time with space? Not really, but do the best you can. Develop things like lines of separation, SOPs for boot washing.
Dr. Joe Armstrong:Have dedicated equipment for certain areas of the farm. Ask questions of the people on your farm. What are they doing in their off time? Do they work anywhere else? We gotta make sure that we have a handle on the people component of this as well.
Dr. Joe Armstrong:Monitor everything for sickness. In this situation, that includes wildlife, including wild birds, cats, foxes, raccoons, skunks. Anything that's around your place, monitor them for illness and deaths. Unexplained deaths of wild birds or wildlife at this point should set off alarm bells. Now how do you keep cattle and wildlife separate?
Dr. Joe Armstrong:Well, if you figure it out, you let me know because I think it's an incredibly easy thing to say, and it is impossible to do. What we're going for in this situation is to minimize the contact wherever possible to reduce our risk because the contact is going to happen. You're not gonna keep birds out of the barn. You're not gonna keep waterfowl off a pasture. You're not gonna keep mice completely out of everything.
Dr. Joe Armstrong:I have yet to see a farm where I don't see at least one cat eventually. They're they appear somehow. So in this situation, we're going for, let's minimize the contact as much as possible, knowing that we can get close, but we're not going to eliminate that risk. Water tanks, big source of potential contamination. We gotta be cleaning them regularly.
Dr. Joe Armstrong:Just the act of emptying and scrubbing and washing things out is a great start. Almost everything that we talk about with a lot of this stuff is dose dependent. So anything we can do to lower the potential viral load that could be there is helpful. Covering feed piles is a big piece of this when you can. Now am I telling you that every single night you gotta go out and cover that entire silage face?
Dr. Joe Armstrong:Is that practical? No. But if you got smaller piles, if you got distillers around, if you've got especially piles on the ground, Smaller piles that are accessible by wildlife. Covering those piles is worth your time. That brings up spills as well.
Dr. Joe Armstrong:Feed spills. Cleaning that up right away. We've known that's a big deal for rodents for a long time. But guess what? Rodents bring other wildlife and we need to be on top of that.
Dr. Joe Armstrong:So the next question that comes up after biosecurity, those are the kind of things I think about what we're trying to do. Obviously, if you have poultry, if you have poultry on your operation, keeping them separate from your cattle is a great idea right now. So if you got ducks or chickens running around, now is the time to decide, hey, maybe we need to figure out how to keep them away from the cattle. That's what we're gonna talk about for biosecurity right now. There will be more information that comes out as we learn more, and there will be more definitive guidelines for biosecurity as we learn more about what's going on.
Dr. Joe Armstrong:The next question is all about the progression of this illness in the farms that have seen it right now. I am not on the front lines, and I do not have eyes on these cattle, and I am not working at a herd directly right now. I can only tell you what I've heard to help you be better prepared. I've talked to farmers. I've talked to veterinarians.
Dr. Joe Armstrong:I can only tell you what I've heard. So beyond what we already know that we discussed in the last episode about what that case profile looks like, the big thing that I'm hearing that we haven't got into specifics on yet is how this thing progresses across a herd. And what I am hearing and what I am told is that we see the Feed drop definitively first. By far, that is the first thing you see. You see everyone backing off Feed, especially in that second lactation and greater mid lactation and later, they back off feed.
Dr. Joe Armstrong:Where we're seeing 1 or 2% come off every 1 to 2 days. And then, usually, in that 7 to 8 day window of being affected, we see giant drops 5% each day all the way out to day 10 or 11. And that's when we start to see, finally, some overtly clinical cattle. Obviously, with a drop in feed comes a drop in milk, and that seems to start coming back up. We hit our low point somewhere in that 10 to 14 days after initially impacted.
Dr. Joe Armstrong:Things start to turn. They come back up. They may not get to where they were before, but at least we're on the rise. So that case profile, that progression might be different if you're already looking. I don't know.
Dr. Joe Armstrong:I have no idea. But maybe you can pick up some of the subtle things early in the process and find some of those cattle that need help and need supportive care early in the game if you know to be looking. That's as much as I know right now. That's as much as I'm gonna share with you about that right now. I've got thoughts.
Dr. Joe Armstrong:I've got ideas. But right now is not a time to be speculating about what's going on and potentials and everything. We need to stick to what do we know and what have we confirmed? And that is what USDA APHIS is for. Last thing, and then I will end this episode.
Dr. Joe Armstrong:The thing that I've heard over and over again is that people are trying to prove prove Koch's postulates. We've had a couple questions because that keeps coming up. What is it? What are Koch's postulates? There's a lot of different ways to pronounce that.
Dr. Joe Armstrong:This is how I say it. Koch's postulates, k o c h. What are they? I think it's important to know. There's some history here.
Dr. Joe Armstrong:There's a cool tale. There's a lot going on here. It may or may not apply to modern medicine, but it has been adapted all sorts of different ways to modern medicine. There's other theories that have been born out of it that maybe apply better, especially because Koch's postulates were defined around mostly bacteria, and now we have viruses in the game. But I think it's still an excellent thing to know as a basic piece of history, but also so that it when it comes up in a conversation, you know the meaning behind using that term.
Dr. Joe Armstrong:So Robert Koch developed this theory with a couple others and then published it. And I think this is the crazy piece. Published it back in 18/90. And, really, it became the gold standard for establishing the microbiological connection to infection and disease. So, Koch's postulates are really just 4 criteria that help us decide whether or not a microorganism causes a disease.
Dr. Joe Armstrong:The 4 criteria are the microorganism must be found in diseased but not healthy individuals, the microorganism must be cultured from a diseased individual, inoculation of a healthy individual with the cultured microorganism must result in the disease, and then finally, the microorganism must be re isolated from the inoculated diseased individual and then be matched to the original microorganism. So, to come up with this in 18/90 and then use it to figure out the bugs associated with not only cholera but also tuberculosis is an amazing feat. And that's why this thought process has become the gold standard for connecting microorganisms to infection and disease. Now, those were the first set. They had to be modified and bent almost immediately after publication, even by Koch, because he found out that they are asymptomatic carriers of certain diseases.
Dr. Joe Armstrong:But still, we're only modifying the first criteria. The microorganism must be found in diseased, but not healthy individuals. There's still differences between diseased and healthy individuals, even if the healthy individual is an asymptomatic carrier. So, I'm hearing this term a lot because we don't know or we have not confirmed that highly pathogenic avian influenza is the causative agent of disease, and it comes up all the time that we need to fulfill Koch's postulates. And that's the reasoning behind making sure we have all the samples, especially all the samples from both affected animals and non affected animals.
Dr. Joe Armstrong:So we can tease out the differences, and we can definitively, using a set gold standard that has been proven time and time again, we can use that to confidently say, Yes, this is the causative agent of disease, or no, it is not. Now, there's a lot more intricacy and knowledge since 1890. We now know that there is a whole another world of complexity that has evolved through host and pathogen interaction. Koch's postulates is kind of the placeholder for every term that could mean following a set standard to prove whether or not there's a connection between a microorganism, infection, and disease. There's updated criteria and those will be used, but commonly, when we say Koch's postulates, that is the placeholder for those set standards for proving that connection.
Dr. Joe Armstrong:I hope that answers some questions for you tonight. And with that little the more you know segment on the end, we'll call it a night. I'd like to go to bed. I'm sure the kids will still be sick in the morning, so I gotta be prepared for that. If you have comments, questions, scathing rebuttals, please send those to themoosroom@umn.edu.
Dr. Joe Armstrong:You can call us at 6126 243610. Catch us on Twitter @UMNMoosRoom and @UMNFarmsafety. Catch Bradley on Instagram @umnwcrocdairy. Check us out on the web, extension.umn.edu. Thank you everybody for listening.
Dr. Joe Armstrong:I'll talk to you whenever I have more. Bye.
