What You Need to Know About Bird Flu - Chasing Life with Dr. Sanjay Gupta - Podcast on CNN Audio

Many of us are setting new personal goals in the new year - like exercising, eating healthier or even trying to lose weight. What does our weight really tell us about our health? Is it possible to feel healthy without obsessing over the numbers on the scale? Are our ideas about weight and health based on outdated beliefs? On this season of Chasing Life, CNN's Chief Medical Correspondent, Dr. Sanjay Gupta is talking to doctors, researchers, and listeners to take a closer look at what our weight means for our health. Plus, what you need to know about the latest weight loss drugs and how to talk about weight and better health with others, especially kids.

What You Need to Know About Bird Flu

Apr 30, 2024

The U.S. is grappling with a recently discovered outbreak of avian influenza in dairy cows, driven by the highly pathogenic H5N1 virus. It's the first instance that the bird flu virus has been detected in US cattle. How concerned should we be about drinking milk or even eating chicken? And could this lead to the next pandemic? Sanjay speaks with epidemiologist Prof. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, about the complexities of the current outbreak and what the public needs to know right now.

Dr. Sanjay Gupta

00:00:00

'Hey, everybody. There is a lot happening in the world right now, so I hope you're checking in on each other and taking good care of each other. No matter what is dominating the headlines, we always want to pay attention on this podcast to the possibility of a viral outbreak and what that means for public health and our overall well-being. That is, after all, how this podcast got started in the first place. Back in those early days when Covid was first spreading and we had a lot more questions than answers. Well, lately we have been paying attention to a very different virus, one that is primarily affecting animals around the world. I'm talking about bird flu, which is caused by the H5N1 virus.

Livestock in multiple states have tested positive for bird flu in recent days.

Now, first U.S. case of a person suspected of catching this version of bird flu from a cow has been reported in Texas.

The FDA says it's gotten positive tests for remnants of bird flu in pasteurized milk in grocery stores.

Dr. Sanjay Gupta

00:00:58

'Now, I want to be clear on something. The federal agencies that are monitoring the situation say that this version of H5N1 does not appear to be a threat to humans at this moment. There's only one confirmed case so far, and it's a person in Texas who had direct exposure to dairy cattle. The person's symptoms are considered pretty mild. Basically, it was conjunctivitis or pinkeye. And that person is only the second case to ever be reported in the United States. But I still got a lot of questions, such as, how did this virus that primarily affects birds - after all, it's called bird flu - how did it start infecting cows and other animals? And could it spread more widely in humans? If that happens, how would we protect ourselves? Just like we did during the Covid 19 pandemic, I found that the best way to address these concerns and questions is to get information from the experts, the people who are addressing this directly and who are often on the ground. So I got in touch with someone who has been studying animal and human viruses and their impact on public health for decades.

Prof. Michael Osterholm

00:02:04

'If there's ever a good time to talk about that concept of one health, animals and humans together, this is it. You know, the real potential for human-related disease, and particularly a pandemic potential is all tied with these animals.

Dr. Sanjay Gupta

00:02:18

That's Professor Michael Osterholm. He's an epidemiologist and the director of the Center for Infectious Disease Research and Policy at the University of Minnesota. And today on the podcast, he's going to explain what we know about the H5N1 virus, how it is spreading, and why he thinks it's safe to keep consuming things like milk and beef. I'm Dr. Sanjay Gupta, and this is Chasing Life.

Dr. Sanjay Gupta

00:02:46

How are you?

Prof. Michael Osterholm

00:02:47

Good, thanks. You know, trying to stay one step ahead of the next infectious agent.

Dr. Sanjay Gupta

00:02:52

Well, let let me let me just just get right to it. H5N1, when you heard that this was starting to to circulate. This is not a new virus. I remember talking about it from Southeast Asia several years ago. First thing that went through your mind when you heard this?

Prof. Michael Osterholm

00:03:10

First of all, I have to really start out with my story with H5N1 because I think it helps set the table for how I interpret what's happening right now. Back in 1996, this virus first emerged in wild aquatic birds in Southeast Asia. And then in 1997, there was actually an outbreak in the markets of Hong Kong with more than 23 individuals infected. A number of them died, and there was great steps taken to, at that time eliminate the virus out of those markets by basically killing all the birds there. And everyone thought, okay, we've now dodged the bullet with this new virus that could be a pandemic agent. And things were looking good. And then it showed up again in Southeast Asia, particularly in Indonesia, Thailand, Vietnam. And I was actually there during this time working on H5N1 when we had 110 to 115 cases a year through 2005 and six. And we kept thinking, we're right on the edge. This is right on the edge of the next pandemic. And then for reasons we really can't say, the number of cases in humans just continue to decrease and decrease. Then along comes 2015, and we suddenly saw 145 cases in duck farmers in the Nile River Valley. Over half of them died. And again, we were activated and said, oh, here it is. It's just about ready to go. And then everything quieted down. And in fact, between 2017 and now we've only had a handful of human cases.

Prof. Michael Osterholm

00:04:38

Why is that what's happened? Well, the virus has actually changed a lot since its first origins, and the one that we are dealing with now has become a virus that is readily killing mammals. Over 200 mammal species have now been infected. It surely has been devastating to the bird population. But in fact, if anything, I think it has gotten farther and farther away from being a serious human virus, a challenge. Meaning that the receptor sites for the virus in human lungs, and their eyes are different than, we see an animal species, other than humans. And so from that perspective, I've been through this drill a number of times. I don't know if this is going to be a real risk to the public in terms of human disease, and that's why I very much support the WHO and the CDC's declaration that this is still low risk for humans. But I do think that it's very important in terms of what it's doing in other mammal species. And the current situation right now, when I heard about the cows, my first reaction was, I'm not so concerned about the cows. I want to know what's going on in the swine that are nearby. Because the swine actually have receptor sites for both bird and flu and human flu viruses. And that's where we see the concept of re assortment, where a bird virus and a human virus get together in one lung and creates a new virus. So I think we're really at a place where I can't tell you what the real risk is to the public.

Dr. Sanjay Gupta

00:06:00

'Is the idea that they would suddenly develop, the ability to attach these receptors - is that a totally random event? Or is that something that you could predict?

Prof. Michael Osterholm

00:06:11

'Well, it is a random event to the extent that, you know, when it happens, such as we're seeing right now, even with H5N1 in in dairy cattle, you know, that was a random event that then became non-random. It became a, you know, a surge of virus activity. And I think that, from a human perspective, my biggest fear is if this were to get established in swine and then we have swine getting co-infected with human viruses and with, bird virus like this, that's when we get the brand new virus. And that has lots of implications. Not only is it, you know, likely or possibly able to cause the next pandemic, but the vaccines that we've developed to date that everyone's putting, you know, their their confidence and probably will have limited impact. We'd have to have the brand new strain. The one that emerged is not the one that circulated right now. So I think in that regard, you know, we have to be prepared for the possibility of the next day reabsorption or series of mutations, even though, you know, it may not happen.

Dr. Sanjay Gupta

00:07:11

So if you're sort of following this along this story of H5N1, if you start to hear that it's circulating in pigs, that would be a concern? That would be a red flag?

Prof. Michael Osterholm

00:07:23

You know, that means I would go from sleeping with one eye open to one and a half eyes open. Yeah, that would make me very concerned.

Dr. Sanjay Gupta

00:07:29

And wondering for for this particular outbreak of H5N1, can you sort of trace sort of how this unfolded and maybe even the timeline a little bit because we're hearing about this now. But when you go back and I started looking at some of these reports out of Texas. There was concerns about sick cattle going back a few months at least, maybe even the end of last year. When do you think that started and how did it move?

Prof. Michael Osterholm

00:07:53

Well, you know, this is public health surveillance 101, and then you're raising a very important question. If you look at how this was initially detected in cattle, it was in dairy cattle. And it wasn't because they were very sick; it was because they had reduced milk production and their milk was discolored. It was off off taste. And at that point somebody flagged and said, wonder what's going on here? And it took literally weeks and weeks before finally, a group of veterinarians from Texas and Iowa State University identified the virus in these animals. In the meantime, it was likely this was occurring widely throughout parts of Texas, at least. And how much of it was from a single bird spillover, meaning a bird infected, got into production animal locations. And remember, this is not a surprise. I, we have numerous pictures of dairy cattle eating at the trough, the food trough with the birds sitting there eating right with them, you know, defecating into that food. So it's not a surprise that you would have that potential contact. But I think, as you alluded to, there is likely, a situation where this actually has been transmitting for months. The only reason we know about it, because you milk cows twice a day and you see exactly what their milk production is, and you know something's off.

Prof. Michael Osterholm

00:09:07

One of the pieces of data that I'm really anxious to see, and I wish FDA would be more forthcoming about this, is there have been a number of groups around the country that have been sampling for this virus and milk using PCR test, which just to assure the listeners here that, you know, this is not any kind of statement about is that infectious virus in the milk. If it's pasteurized, you can have remnants of the virus that are detectable by PCR, but there's no live virus on the milk. Same thing is true with E coli, or listeria, or salmonella. You know, when you pasteurize that you kill those agents. They don't disappear, however. And so this is important data, because I think you're going to find that the milk was contaminated, in a sense, in many locations in this country where we've not had any reports of of operations, where there have been sick animals. What it's pointing out is that this was going under the radar, and that we were seeing a lot of these production animals that were not at all seriously ill, but actually infected. And so I think to me, this is an outbreak that is a lot further along in its course than the more recent recognition would suggest.

Dr. Sanjay Gupta

00:10:13

It it started in birds. And then how did the cattle spread it from one to another?

Prof. Michael Osterholm

00:10:18

'I can't tell you how the cattle-to-cattle transmission occurred, and I still reserve judgment on that to say that I'm not sure that it always was cattle-to-cattle. I think once it's on a farm, the birds there could still have continued to contaminate the food sources, etcetera.

Dr. Sanjay Gupta

00:10:32

The idea that the cows are getting sick, they're not dying, but that they could spread it from one cow to another, or spreading in the milk, or spreading in the process somehow. I guess all those things are on the table.

Prof. Michael Osterholm

00:10:43

Yeah, they all are. I think the milk one is a concern is is it from the milking equipment is transmitted from udder to utter? Which would be a novel way to transmit at this point we just don't know. It's all speculation. We've got a lot of work that needs to be done. But I still think that, you know, respiratory transmission or ingestion somehow is going to be very important.

Dr. Sanjay Gupta

00:11:03

I heard some reports, correct me if I'm wrong, that there were cats on these farms who died.

Prof. Michael Osterholm

00:11:08

Yeah. Cats are actually well known to get H5N1 and be, it's a fatal disease. And of course, cats are constantly drinking the milk that spills etcetera on the farm. So you know, you know, you don't see a dairy operation without cats, okay. Because one of the things that help keep the rodent population down, but they also enjoy the riches of the milk. And so that wouldn't be a surprise at all.

Dr. Sanjay Gupta

00:11:33

You may have seen this, but Rick Bright, who you and I both know, he he posted something where he said exactly what you said, but he said, you know what, I probably will avoid drinking milk for a little period of time. Do you think that he's he's overreacting or better safe than sorry?

Prof. Michael Osterholm

00:11:52

Well, Rick is a dear colleague, and I would always let him decide for himself what he wants to do. He's a brilliant man. For me, I don't find it at an increased risk. When you have milk, remember this goes from the milking machine to a bulk tank on the farm. And you get lots of mixing that occurs. So unless every animal on the farm was infected, you get a dilution factor, even if there's very high levels of viruses there. That bulk tank then gets added to a large truck's bulk tank that comes and picks up the milk from many farms. Then that milk is delivered to the pasteurizing plant, where then it's added with many, many trucks of milk. Okay, each time that happens, you have a major dilution of whatever was introduced into the milk. Well, we have many levels, I think, of protection here because the dilution factor that would occur even with heavily contaminated cows contributing from one farm into the milk supply. By the time it got to pasteurization, it would be at very, very, very low levels.

Prof. Michael Osterholm

00:12:53

You know, it's like what we see with wastewater testing for Covid. You know, we don't see that as live virus in there necessarily. It's a remnants by PCR testing of what once was an infection that got excreted. So so I'm confident at this point from my own self and my family, that they could drink the milk and not be concerned. Where I come back to is and you surely covered this. We unfortunately have, a group of individuals in this country that believe, right unpasteurized milk is what you should be using. And we continue to see outbreak after outbreak of salmonella, you know, E. coli, listeria, any number of these agents with that.

Dr. Sanjay Gupta

00:13:32

So I think that's a really important point for the vast majority of people listening. As long as you're drinking pasteurized milk, you should be okay at this point.

Prof. Michael Osterholm

00:13:39

Yeah.

Dr. Sanjay Gupta

00:13:40

Quick question about that. Flu viruses, if you eat them or in this case, drink them, I was always sort of under the assumption that your, your gastric acids and stuff would essentially denature that virus. I mean, no one is suggesting you should drink live virus, but with H5N1, if it did get into your stomach, can it still cause an infection the way a GI virus would?

Prof. Michael Osterholm

00:14:03

Yeah. You're asking a really critical question that, you know, I've spent a large part of my 50 years in this business working on flu, and I can't answer for you after all those years. The sense is, is that with ingestion, it's actually still basically created an aerosol like event as you consume the food that then is actually inhaled. Now I qualify that, you know, the, the issue about, where is all this virus and the udder coming from? Is there replication in the udder? We've never thought about that. And so I think this is a moment of great humility among flu researchers. At least they should have humility. Because if this virus can grow widely and in milk production, because it's basically growing in the udder, then at that point you have to say, well, where else in the body might this potentially grow? But I think right now the consensus is that this is not a gastrointestinal infection as such.

Dr. Sanjay Gupta

00:14:59

Any concerns about eating meat?

Prof. Michael Osterholm

00:15:01

No, none for me.

Dr. Sanjay Gupta

00:15:04

After the break, more of my conversation with epidemiologist Michael Osterholm. He's going to share why detecting outbreaks like this is not easy and what we can do if people start getting sick.

Dr. Sanjay Gupta

00:15:24

You mentioned that, you know, somebody probably noticed that their dairy cow was not making as much milk or the milk looked different. And then they flagged that what you're describing is the earliest stages of surveillance. How how much of that sort of surveillance, just in your experience, is based on the goodwill of these farmers versus a organized system like what incentivized that farmer, for example, to flag this? And is is that surveillance system good enough?

Prof. Michael Osterholm

00:15:52

Well, I think first of all, we have to understand why do we handle different farm production animals with flu infection in the ways we do. For example, if we have virus emerging in turkey or chicken egg laying facilities, the first thing you want to do is get in quickly and basically put these birds down. And the reason is, is because we know that once it starts in a facility, it spreads very, very quickly and virtually all will die. But what's even more important is the USDA has a reimbursement program. So to detect these problems early, they will reimburse you for the birds you put down, not for the birds that died before you put them down. And so they have every interest in getting this detected very, very quickly.

Prof. Michael Osterholm

00:16:40

Well, that doesn't exist for the swine in the bovine or cow industry, okay. So there's no real incentive to find this early, particularly if your animals are not going to die, but just for a period of time, be somewhat ill or lack of production of milk. And so there isn't a great incentive. And in fact, most farmers today in this area don't want to know. And we've had real challenges. Where I can tell you we have confirmed examples or even USDA veterinarians have said to farmers, well, I wouldn't have scored at this point. It's not going to make any difference on your farm. And so we have a disincentive. Now, you know, I can say, as someone who deals with viruses for both humans and animals, to me this is very important. But if you're someone on the farm side, you'll say, well, it's only the animals I'm worried about and we're not going to see any improvement in their outcome by testing. So we need to really rethink the economic loss reimbursement programs for early detection for all farm animals. With the idea that it's not just about the farm animals. But again, as I pointed out, I want to know what's going on in swine right now. I mean, this is really important, and we have no incentive for farmers to, in fact, do testing on swine. If anything, it's a major disincentive. And so this this is an economic model kind of clashing with the public health model. So your point about surveillance is really important. I think right now our surveillance is actually very poor for this. And that's a real challenge because it's now keeping us as a human surveillance side from understanding what what is happening with the virus. How is it changing?

Dr. Sanjay Gupta

00:18:14

It's interesting to think that just because of the good nature, goodwill of some of these farmers, that we this was sort of flagged. It's not as organized a system as you would like. With pigs even maybe more of a problem because there's no incentive. What would happen to the pigs? I mean, is it just sick pigs, or are you waiting for them to die or what's what's happening?

Prof. Michael Osterholm

00:18:36

Well, you know, our group has been involved with researching this issue. We detected a number of outbreaks in humans associated with going to county fairs. And humans got sick, and they had close contact with the pigs. When we went in and sampled the pigs, they hardly had any symptoms at all. Mild, mild respiratory like symptoms, but not noticeable if you hadn't been alerted to, they might be infected. And so the same thing I think could happen here, where you would see very little illness in a pig that would index the suspicion that flu virus is circulating. So I think that, we can't count on using pigs right now as an indicator population of widespread flu virus transmission, even though it could be occurring. And we surely now have pretty much the same information for cattle. And remember, on top of all of this is the wild bird population. You know, we've just experienced major migration again, seasonal migration through North America. And, you know, we've seen now time and time again in bird related deaths, particularly in poultry flocks, in various parts of the country. As the migration moved northward, we can see these flocks getting infected. And so we have to be careful not to think of this as a Texas situation that then spread to a couple of places. That surely has happened. But it could be overlaid on a widespread transmission that's been occurring in cattle, and we've just not picked it up because we've had birds from the east coast to the West coast going north, and they've been bringing virus with them wherever they go.

Dr. Sanjay Gupta

00:20:05

So on one hand we say, look, if we see this in pigs, that would be, a concern given the overlap of receptors that pigs have and humans have. At the same time, we're saying it's not necessarily likely that pigs would be getting sick. So we want to look for it, but we're not exactly sure what to look for. Is there a larger message in there, Mike?

Prof. Michael Osterholm

00:20:25

Oh, absolutely. I can tell you, Sanjay, I have been pushing USDA and the FDA over the course of the past few weeks. We've got to do a much more sampling in swine. Again, and that is not because I think there are such a, you know, affected animal species relative to what it's doing to other animal species or, you know, it's killing largely of sea mammals, etcetrta. That is the gateway to human infection. I'm convinced of that. And so as much as we might be concerned about exposure to cattle, I think the exposure is to the pigs. And I think that we could be sitting on that very same situation right now, where we do get one of these H5n1 ones that gets in a pig, respiratory tree, and then same time we see another bird virus get there, or another human virus. And we have re assortment.

Dr. Sanjay Gupta

00:21:14

You've been sort of pounding on the USDA and the FDA for more sampling. Is there sampling going on? I mean how would you how would you sort of rate it right now?

Prof. Michael Osterholm

00:21:22

'Not good. I think the there's a culture shock environment right now at USDA. You know, initially they wanted to just say, look it, you know, no harm, no foul. You know, the animals aren't dying. We're we're here to protect our producers. And, you know, what do we need to do different? And they were missing the whole point of what this means for human health. And this is never a good time to talk about that concept of one health. Animals and humans together. This is it. And, you know, the real potential for human related disease, and particularly a pandemic potential is all tied with these animals. And so I think that we've got to continue to push on that. Also, I think we have to be very careful about happy talk. I think there's been far too much happy talk that's occurred as it relates to - well we've got vaccines. Well, you know, we don't really have vaccines. Remember, the virus is going to infect us if it does, as a potential human transmitted virus, it could lead to a pandemic, is going to be different than the virus we have right now. Remember in 2009 we had an H1N1 vaccine for seasonal H1N1. It didn't work at all against the pandemic, H1N1. That was the same type of virus. Okay. So we have to be very careful about assuming that we're going to have vaccines that have any real effectiveness until the actual virus that infects humans, causing potentially the next pandemic, actually emerges. Because it's not going to be the same one that we're seeing right now.

Dr. Sanjay Gupta

00:22:50

My parents, who I've talked about before to you, they they're in their 80s. They live in Florida. You know, I think they're pretty practical folks, but should they be doing something different? If they're more vulnerable to this? Should they keep Tamiflu, for example, in their, in their medicine cabinet?

Prof. Michael Osterholm

00:23:05

You know, I, I at this point I wouldn't keep it there just because over time, if it's not in the right time and temperature and bathrooms are the worst thing that can happen because the humidity in terms of breaking down the product, but because they have a son who is so informed he's going to call them at the moment, they need to go get their script on Tamiflu and and then they'll be fine.

Dr. Sanjay Gupta

00:23:25

All right. Good advice. And I'll, I'll promise as well to anybody listening that we will be talking about this. And so hopefully everyone again there's not enough for the world. But but that aside, we'll make it clear that this is the time now to maybe have Tamiflu. For humans out there. The consumer obviously don't drink unpasteurized or raw milk. You shouldn't be doing that regardless of the situation that we're in now.

Prof. Michael Osterholm

00:23:51

Yeah.

Dr. Sanjay Gupta

00:23:51

Other precautions you think people should take.

Prof. Michael Osterholm

00:23:55

I think right now is trying to limit the exposure to the workers, and following them closely to know what's happening. At this point, you know, we have no evidence of human to human transmission. But again, you want to be on top of that. And, you know, as Willie Sutton once said, why do you rob banks? That's where the money is. You know, if you're going to look at where transmission is going to go to a human and then to a human, to a human, it's going to be these farm workers. And so I think this is where we really want to concentrate on right now.

Dr. Sanjay Gupta

00:24:24

Do you think with everything that we know now, it is possible, at least in the United States, just this just focusing on the United States for a second to, to essentially become pandemic proof, like if we said, Mike, whatever we need to do, we don't want to deal with the pandemic again, can we basically guarantee that we could avoid a pandemic?

Prof. Michael Osterholm

00:24:45

You know, that's a really, wonderful goal. And I would sure love to get there. And with the work we're trying to do with the vaccines for both coronaviruses and flu, because these are still the two primary agents that are going to cause pandemics around the world. I'd say it's a very laudable goal. Do I think it's going to happen? No, I think not. I think we're going to always have to have pandemic preparedness front and center.

Dr. Sanjay Gupta

00:25:08

Now, if you pay attention to nothing else, remember these two things. First of all, humans are not likely to get infected or spread this strain of bird flu. Second of all, pay attention to the pigs. They're kind of like the canary in the coal mine here. They are susceptible to different viruses, which could mix and match and possibly form a new, more problematic virus. And as Professor Osterholm pointed out, pigs may not get sick. And that is why we need to be diligent about systematically testing them. Keep in mind that pig receptors and human receptors, they overlap quite a bit. So if the pigs start to get sick from the bird flu, humans may very well be next. So pay attention to the pigs.

Dr. Sanjay Gupta

00:25:56

And look, I know it can be frustrating and even a little scary to hear that we don't know everything about this virus, and we certainly don't know how it might evolve. I know people want black and white answers to their questions about this stuff, but when it comes to public health, some things are predictable. And others, such as the reabsorption process of viral genomes. That's less certain, but we're going to continue to rely on people like Professor Osterholm to tell you what we know and what we don't know. We're going to be really honest about that, and we're going to keep an eye on future developments.

Dr. Sanjay Gupta

00:26:31

Coming up next week and chasing life:

CNN Medical Correspondent, Meg Tirrell

00:26:34

'I guess that's sort of the questio n is - when you say linked and when can you say ultra processed foods cause health problems?

Prof. Marion Nestle

00:26:43

Well, you can do that when you have a controlled clinical trial. And guess what? We have one.

Dr. Sanjay Gupta

00:26:48

'My colleague Meg Tirrell unpacks the do's and don'ts behind unprocessed foods. What she finds is probably going to change the way you shop for groceries. And one more thing before I let you go. The team is already hard at work on our next season of the podcast. It's going to be our 10th season. Hard to believe. We want to hear from you. Leave us a message at (470) 396-0832 and tell us this: how do you chase life? Your message could be used on an upcoming episode.

'Chasing life is a production of CNN audio. Our podcast is produced by Eryn Mathewson, Jennifer Lai and Grace Walker. Our senior producer and showrunner is Felicia Patinkin. Andrea Kane is our medical writer. Dan Zula is our technical director and the executive producer of CNN Audio is Steve Lichteig. With support from Jamus Andrest, Jon Dianora, Haley Thomas, Alex Manasseri, Robert Mathers, Lainey Steinhart, Nicole Pass-through, and Lisa Nomura. Special thanks to Ben Tinker, Amanda Sealey, and Nadia Kounang of CNN Health and Katie Hinman.