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Pandemics: History and Prevention – Part 2

Today we conclude our series on the history and prevention of pandemics.

This episode features audio from Pandemics: History & Prevention. Visit the video pages for all sources and doctor’s notes related to this podcast.


I’m Dr. Michael Greger and this is Nutrition Facts. 

There’s one thing we’ve been thinking about a lot lately, and that’s how to stay healthy in the middle of a global pandemic. Especially since we’ve learned that those with underlying health problems like obesity, hypertension, diabetes, and heart disease are more likely to have serious complications if they contract COVID-19. So what do we do? We try to stay healthy – with evidence-based nutrition.

Today on the show part two of the talk I gave in 2008 when I was Public Health Director at the HSUS in Washington DCon how to prevent the emergence of pandemic viruses.

Where did this virus come from? Well, the current dialog surrounding avian influenza speaks of a potential H5N1 pandemic as if were a natural disaster—a hurricane, earthquake— of which we couldn’t possibly have control. The reality, though, is that the next pandemic may be more of an unnatural disaster of our own making. In poultry, bird flu has gone from an exceedingly rare disease to one which now pops up every year. The number of outbreaks of highly pathogenic avian influenza in the first few years of this century have already exceeded the total number of outbreaks recorded for the entire 20th century. If one looks at the number of birds involved, the escalation is even more dramatic. At this scale, not even a blip until the 1980s. Bird flu seems to be undergoing evolution, in fast forward. As one leading flu expert told science, “We’ve gone from a few snowflakes to an avalanche.” And the increase in chicken outbreaks has gone hand in hand with increased transmission to humans.

A little over 10 years ago, essentially no known people—not a single person known to get sick directly from bird flu, but, since H5N1 arose in 1997, four other chicken flu viruses have affected people from Hong Kong to New York City. We can add another pink ring for the four cases in England and Wales last year. In the Netherlands outbreak, there’s evidence from a government investigation of a thousand people infected, with symptomatic poultry workers passing the virus on to a whopping 59% of household family members. Human-to-human transmission at a rate of seasonal flu. So, ten years ago or a dozen years ago, essentially no one was getting infected with bird flu, and now there’s been over 1,000 cases in continents around the world. Now the Netherlands outbreak––30 million chickens died, but only one person; one of the attending veterinarians tragically died, so the Netherlands virus was good at spreading, but not at killing.

H5N1 is kind of the opposite, right? H5N1 isn’t even good at spreading from birds to people. Look, it’s been around 10 years, over 10 years. Only a handful of people, a few hundred people, have become infected. And currently— certainly not good at spreading from person to person. But the human lethality of the strain is ferocious: over 10 times deadlier than the worst flu virus on record, that which triggered the pandemic of 1918. So what the Netherlands outbreak shows us is that this virus can evolve to go directly human to human. What H5N1 shows us is that this virus can evolve into an efficient human killer. If this trend is allowed to continue, our nightmare may one day be realized. The worst of both worlds, contagious and deadly. So, to slow down or stop this rapid recent emergence of highly pathogenic flu viruses, one must first ask well, what triggered this avalanche in the first place? What has changed in recent decades to bring this all upon us?

The emergence of H5N1 has been blamed on free-ranging flocks and wild birds. But people have been keeping chickens in backyards for thousands of years, and birds have been migrating for millions. Bird flu has been around forever. What turned bird flu into a killer? Well, the senior correspondent of “News Hour with Jim Lehrer” posed that question to Dr. Webster, the so-called godfather of flu research. “Was there something qualitatively different about this last decade, made it possible for this disease to do something it’s never done before? Some kind of changing conditions that suddenly lit a match to the tinder?” Webster replied. He said, “Farming practices have changed.” He talks about growing up on a farm, but “now we put millions of chickens into a chicken factory, next door to a pig factory. And this virus has the opportunity to get in one of these chicken factories, and make billions and billions of these mutations continuously. And so what we’ve changed is the way we raise animals, and our interaction with those animals.” And then, he talks about how the virus is escaping from the factories, infecting wild birds. He says that’s what’s changed. We’ve changed the way we raise animals. But, we changed the way we raise animals by the billions.

The number of chickens we slaughter every day, spread wing to wing, would wrap more than twice around the world’s equator. The big shift in the ecology of avian influenza has been the intensification of the global poultry sector. The developing world meat and egg consumption has exploded, leading to these industrial-scale commercial chicken facilities, arguably the perfect storm environment for the emergence and spread of these so-called “super strains” of influenza. In the early 1980s, nearly all the chickens in China were raised in tiny backyard outdoor flocks, but now there are 63,000 CAFOS in China—concentrated animal feeding operations— with a few of these so-called factory farms confining 10 million birds on a single farm. The World Health Organization blames emergence of H5N1, SARS, Nipah virus, all these new deadly emerging Asian viruses, in part on what they call the overconsumption of animal products in this intensive animal agriculture.

The Food and Agriculture Organization of the United Nations starts out, “There seems to be an acceleration of human influenza problems in recent years.” This is what they mean. This is from the World Health Organization. These are all the new influenza viruses infecting human beings over the last century or so. Now, turn your attention to just 1995 on. Seems to be kind of snowflakes to an avalanche in people, too; but why? Well, according to the world’s leading agricultural authority, this is expected to largely relate to the intensification of poultry production, and possibly pig production as well. They elaborate in an internal FAO document, “Chicken to chicken spread, particularly where assisted by this intensive husbandry conditions, causes the virus to shift, adapt to more severe highly pathogenic type of infection. Intensive production favors the rapid spread of the viruses in the so called ‘hotting up’ of the virus from low pathogenicity to highly pathogenic types.”

Factory farms, it seems, can be thought of as the incubators for the emergence of highly disease-causing strains of this virus. In this diagram here, they actually trace the path of a human pandemic, starting with increased demand for poultry products, and ending up with a virus capable of human-to-human transmission. The United Nations, in fact, has called on all governments to fight the role of what they call factory farming. Quoting from a UN press release, “Governments, local authorities, international agencies need to take a greatly increased role in combating the role of factory farming, which combined with these live bird markets provide ideal conditions for the virus to spread and mutate into a more dangerous form.”

All bird flu viruses start out harmless to both birds and people. Very important to understand. They start out harmless. Avian influenza has existed for millions of years as a harmless intestinal virus of aquatic birds like ducks, waterborne virus. I said, well, how does a duck’s intestinal bug end up in a human cough? Well, in people, the virus must make us sick in order to spread, must make us cough in order to shoot virus from one person to the next. With the virus’s natural reservoir, aquatic birds like ducks, the virus doesn’t need to make the ducks sick in order to spread. In fact it’s in the virus’s evolutionary best interest not to make the ducks sick as dead ducks don’t fly very far. So. the virus silently multiplies, and the intestinal lining of the duck is secreted out into the pond water, is swallowed up by another duck, and the cycle continues, as it has for millions of years, and no one gets hurt. But if an infected duck is dragged to a live bird market, for example, crammed in cages high enough to spot a virus-infected feces on land-based birds, terrestrial birds like chickens, well then, the virus has a problem. If the virus finds itself in the gut of a chicken, it no longer has the luxury of easy waterborne spread. Chickens aren’t paddling around in the pond, so the virus must mutate or die.

Unfortunately for us, mutating is what influenza viruses seem to do best. So, in its natural reservoir it’s been described as being in total evolutionary stasis, harmless, but when thrown into a new host, like land-based birds, it quickly starts mutating, acquiring mutations to adapt to its new host. In the open air, it must resist dehydration, for example, and it may have to spread to different organs to find a new way to travel. The intestines ain’t going to work anymore, and they may find the lungs and become an airborne pathogen, which is bad news for terrestrial mammals, such as ourselves. Goes into chickens as an aquatic virus, but may come out as the flu. In its new host, the more virulent, the more violent, this virus becomes, the quicker it may be able to overwhelm the immune system of its new host. But, if the virus becomes too deadly though, it may not spread as far. In an outdoor setting at least, if the virus kills its host too quickly, the animal may be dead before it has a chance to spread to too many others. So in nature, there’s kind of a natural limit on how virulent these viruses can get––or at least there was until now.

Enter intensive poultry production. When the next beak is just inch––inches––away, there may be no limit to how nasty these viruses can get. Evolutionary biologists believe that this is the key to the emergence of hyper-virulent, predator-type viruses like H5N1. Disease transmission from immobilized hosts. See, when you have a situation where the healthy cannot escape the disease, where the virus can knock you flat, and still transmit just because you’re so crowded, then there may be no stopping rapidly-mutating viruses from becoming truly ferocious. And this may explain the virus of 1918, rising out of the trenches of World War I. There were these crowded troop transports; boxcars were labeled “8 horses or 40 men.” So, when this harmless virus found itself in these kind of conditions, it turned deadly. Millions forced together under cramped quarters; no escaping a sick comrade. This is thought to be where the virus of 1918 gained its virulence.

From the virus’s point of view though, these same trench warfare conditions exist today. In every industrial chicken shed, every industrial egg operation, confined, crowded, stressed, but by the billions, not just millions. The industry is slowly waking up to this growing realization that viruses previously innocuous to natural host species have in all probability become more virulent by passes through these large commercial populations.

This from an industry journal. Starts out harmless, turns deadly. That’s what these conditions may be able to do. This is not arguably how animals were meant to live. So how does the poultry industry feel about the possibility that its own animal factories may produce a virus capable of killing millions of people around the world? Well, the executive editor of “Poultry” magazine wrote an editorial on just that topic. She wrote, “The prospect of a virulent flu, to which we have absolutely no resistance is frightening. However, to me, the threat is much greater to the poultry industry. I’m not as worried about the U.S human population dying from bird flu as I am that there will be no chicken to eat.” This is this is how the Department of Interior puts it. “Domesticated poultry is the necessary stepping stone to create a pandemic strain of influenza.” H5N1 found a way, it seems, not only to kill people directly, but seems to have gone full circle, reinfecting its natural hosts––migratory aquatic species––who could potentially fly this factory farm virus to continents around the world.

Now, unfortunately for us, there’s some quirk of evolution. The respiratory tract of a chicken seems to bear striking resemblance to our own primate respiratory tract on a molecular level, on a virus receptor level. So as the virus gets better at infecting, killing chickens, the virus may be getting better at infecting and killing us. Virologist Earl Brown, specialist in the evolution of influenza viruses. “You have to say,” Dr. Brown concluded, “again, this high-intensity chicken rearing, really the perfect environment for the evolution for generating virulent avian flu virus.”

Now in contrast, there has never been a single recorded emergence of a highly pathogenic flu virus ever from an outdoor chicken flock. Never once has a dangerous deadly virus ever arisen that we know of in chickens kept outside. You can breed a deadly virus here. It can escape. In fact, backyard birds, free-ranging flocks, even wild birds, but that transition from harmless to deadly always seems to happen in these kind of conditions, because of the overcrowding. Remember, transmission from immobilized hosts, because of the sheer numbers. Because of the inadequate ventilation, the dankness helps keep the virus alive. Because of the stress crippling their immune systems. Because of the filth. The virus is in the feces that they’re lying in, which, decomposing, releasing ammonia, burning their respiratory tracts, predisposing them to respiratory infection in the first place. And because there may be no sunlight. The UV rays and sunlight are actually quite effective in destroying the influenza virus. 30 minutes of direct sunlight completely inactivates H5N1, but it can last for days in the shade, and weeks in moist manure.

So, you put all these factors together, and what you have is this kind of perfect storm environment for the emergence and spread of new super strains of influenza. But what about biosecurity? Don’t we want all the birds confined indoors, away from waterfowl? I mean, does it matter? If these kind of conditions can turn a harmless virus into a deadly virus, if the harmless virus can’t get inside in the first place? Well, an FAO research report addressed this very question. They, in their evidence-based analysis, they looked at the best data set available: a massive survey of flocks in Thailand, in which over a million birds were tested for H5N1, in factory farms and backyard flocks. And what they expected to find was that backyard flocks would be at higher risk for infection, because they’re just out there in the open. What they found was exactly the opposite. They found that backyard flocks are at significantly lower risk of infection, compared to commercial scale operations. Industrial quail and chicken operations were at least four times more likely to become infected than backyard flocks. So, not only may factory farms be the incubators for the original emergence of high-path strains, based on the best science available, they may also play a role in the spread, the subsequent spread of the virus as well––in part because of the massive inputs and outputs required for this industrial style of animal agriculture. Tons of feed and water go in. Tons of waste comes out. Tens of thousands of flies buzzing around. And, these high-volume ventilation fans blowing dust and waste out into the countryside, potentially contaminating the air, the soil, insects, rodents, transport. Industrial-style production can lead to industrial-style contamination of the environment.

Researchers at Johns Hopkins University School of Public Health looked back and realized that their conclusions were actually consistent with other high path outbreaks, whether in the Netherlands, Canada, Italy, other diseases. Factory-farms consistently at higher risk. They concluded that there’s no empirical evidence to support this myth that backyard flocks are somehow the crux of the problem. And again, people have been raising birds in their backyards for about 4,000 years before this disease erupted out of control. On other factors, the studies have uncovered widespread disregard for biosecurity, even in developed countries. which claim to have the best biosecurity in the world. According to North Carolina University Poultry Health Management, high biosecurity is still wishful thinking in many areas of intensive poultry production.

A bird flu outbreak in Virginia in 2002 led to the deaths of four million birds. Found its way inside 200 factory farms, highlighting just how wishful the thinking is that industrial poultry populations are somehow completely protected against this kind of infection. Based on the rapid spread of avian influenza in Virginia recently, this decade, USDA poultry virologists conclude the obvious. That biosecurity on many farms is simply inadequate. Investigators from the University of Maryland surveyed chicken facilities throughout the Delaware, Maryland, and Virginia peninsula, perhaps the most concentrated density of chickens in the world, and concluded that U.S. chicken flocks were constantly at risk for infection, triggered by these poor biosecurity practices. But, even if the industry had perfect compliance with these guidelines, even if everyone going in and out stepped in antiseptic foot baths, scrubbed their boots, washed their hands, even with perfect compliance, it likely would not be enough.

We now know that H5N1 can be carried by flies. You cannot keep flies out of a poultry shed. See, H5N1 is a biosafety level 3+ pathogen. That means in a laboratory setting, this virus must only be handled in unique high containment buildings, specially engineered with airlocks, double-door access, shower in, shower out, all floors, walls, ceilings sealed and waterproofed. All electric outlets, phone cords, caulked, collared, sealed to prevent any air leaks. All surfaces decontaminated daily. All solid waste incinerated. That is how you’re supposed to handle this virus. That’s biosecurity. In contrast, the global industrial poultry industry seems to be breeding viruses like H5N1 at essentially biosafety level zero. So, the poultry industry may not only be playing with fire with no way to put it out, they may be fanning the flames, and firewalls to contain this virus do not yet exist.

Unfortunately, a leading USDA poultry virologist told an international gathering of bird flu scientists, “Unfortunately this level of biosecurity just doesn’t exist in the United States,” and doubts really, it exists anywhere in the world. And according to emeritus poultry professor, author of Handbook on Livestock Diseases, standards of biosecurity may actually be in decline in an attempt for the industry to cut costs. Now biosecurity measures as they’re currently practiced are certainly better than nothing, but may not be something we want to stake the lives of millions of people upon for the sake of cheaper chicken.

A pandemic caused by H5N1 or some comparable future bird flu virus has the capacity to trigger one of the greatest catastrophes of all time. So, to decrease the risk of generating increasingly dangerous bird flu viruses, the global poultry industry must reverse course, away from greater intensification by, for example, here, in the annals of New York Academy of Sciences, replacing these large industrial units with smaller farms with lower stock and densities of animals, which could potentially result in less stress, less disease susceptibility, less intense infectious contents, and lower infectious loads across the board.

In 2007, the Journal of the American Public Health Association published an editorial that went beyond just calling for de-intensification of the poultry industry. They questioned the prudence of raising so many chickens in the first place. In their editorial, “Chickens Come Home to Roost,” it is curious that changing the way humans treat animals—most basically ceasing to eat them, or at the very least radically limiting the quantity of them that is eaten—is largely off the radar as a significant preventive measure. Such a change, if sufficiently adopted or enforced, however, even at this late stage, could still reduce the likelihood of the much-feared influenza pandemic. It would even more likely prevent unknown future diseases that, in the absence of the change, may result from farming animals intensively and killing them for food. Yet humanity does not even seem to consider this option. We don’t tend to shore up the levees until after the disaster. Hopefully it won’t take a pandemic before we take these recommendations into account. The editorial concludes, “Those who consume animals not only harm those animals and endanger themselves, but they also threaten the well-being of future generations on this planet.”

To switch avian images, it is time for humans to remove their heads from the sand, and recognize the risk to themselves that can arise from their maltreatment of other species. How we treat animals can have global public health implications. It’s not surprising, then, that the American Public Health Association, the largest association of public health professionals in the world, has called for a moratorium on factory farms, urging all federal, state, and local authorities to impose a ban on the building of new intensive livestock operations to protect the health of the local communities in terms of air, water, land contamination, pollution. The prudence of this measure certainly grows with our increasing understanding of the role that these operations play in emerging infectious disease.

I’m often asked how the industry responds to this kind of sentiment from the scientific community? Well, last summer the United Nations released yet another report on the global health risks of intensive animal agriculture. Let me show you that how U.S. agribusiness responded to this report. “Feedstuffs” is America’s leading agribusiness publication, and, in an editorial, responded this way to the FAO research report. “FAO claims to use scientists to generate its reports, but I wonder if those scientists don’t resemble a bearded guy living in a cave in Pakistan, who wants the U.S. on its knees?” All too typical of the kind of “you’re with us or against us” industry attitude, unfortunately. Now, this is an extreme example.

There are those within industry who can take a step back and look at the longer-term view. Avian health expert and longtime industry insider, Ken Rudd, wrote a really candid article in Poultry Digest called “Poultry Reality Check Needed.” Drawing on his 37 years’ experience from within the poultry industry, he concluded with these prophetic words. He said, “Now is the time to decide. We can go on with business as usual, charging headlong towards lower costs, or we can begin making prudent moves necessary to restore balance between economics and long-range avian health. We can pay now, or we can pay later, but it should be known and it must be said one way or another, we will pay.”

So, cutting down our consumption of chickens and fighting the role of factory farming, as the United Nations has called for, may indeed prevent the emergence of future viruses, but H5N1 has already been hatched, already spread and mutated into a more dangerous form, and now that is endemic in poultry populations across two continents, eradication is unlikely. Dr. Michael Osterholm is the director of the U.S. Center for Infectious Disease Research and Policy, an associate director within the Department of Homeland Security. He tried to describe what an H5N1 pandemic could look like in one of the U.S. leading public policy journals, called Foreign Affairs. He asked policymakers to consider the devastation of the 2004 tsunami in South Asia. He said, “Duplicate the tsunami in every major urban center and rural community around the planet. Simultaneously add in the paralyzing fear and panic of contagion, and we begin to get some sense of the potential of pandemic influenza.” That’s what he thinks it could be like. A tsunami in every city, every town, everywhere people drowning in their own bodily fluids. Or, we could imagine Katrina. Imagine every city, New Orleans around the world at the same time, all perhaps because people insisted on eating cheaper chicken.

The next pandemic may be more of an unnatural disaster of our own making. A pandemic of “even moderate impact may result in the single biggest human disaster ever, far greater than AIDS, 9/11, all the wars of the 20th century, and the tsunami combined, has the potential to redirect world history, as the Black Death redirected European history in the 14th century.” Hopefully, the direction world history will take is away from raising birds by the billions under intensive confinement, so as to potentially lower our risk of us ever being in this precarious place ever again.

My intention today was just to focus on primary prevention, getting to the root cause, but with the unprecedented spread of this truly precedented virus, it is important that everyone be prepared for the next influenza pandemic. So let me just throw out some resources. The CDC has set up an excellent pandemic preparedness website: pandemicflu.gov. If you click across here, you will find pandemic preparedness checklists for businesses, schools, communities, faith-based groups, all the way down to individual and family preparation, which really focuses on getting everyone right now to stockpile weeks of essential supplies to shelter in place during a pandemic, isolating ourselves and our families in our homes until the danger passes. The U.S. Department of Homeland Security Is now using as a key planning assumption that the U.S. population may be directed to remain in their homes under self-quarantine for up to 90 days per wave of the pandemic, to support social distancing. Kind of like a snow emergency, where you’re just told to stay inside; don’t go out unless it’s an emergency. But instead of lasting a day or two, lasts weeks or even months. Everyone ready to stay in their homes for three months? If we have to go out to the corner store during a pandemic to buy toilet paper or something, we may be bringing back to our family more than just groceries.

Let me end with a quote from the World Health Organization. The Bottom Line. “The bottom line is that humans have to think about how they treat their animals, how they farm them, how they market them— basically the whole relationship between the animal kingdom and the human kingdom is coming under stress. In this age of emerging plagues, we now have billions of feathered and curly-tailed test tubes for viruses to incubate and mutate within billions more spins at pandemic roulette. Along with human culpability, though, comes hope. If changes in human behavior can cause new plagues, well then, changes in human behavior may prevent them in the future.”

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Thanks for listening to Nutrition Facts. I’m your host, Dr. Michael Greger.

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