An Interview with Dr. Michael Greger

I was intrigued (and disturbed) by a book I just read online -- www.BirdFluBook.org -- by Michael Greger, M.D. about the potential of a deadly flu pandemic, the likes of which we have never seen. Greger very clearly delineates how a virus begins, mutates, and becomes dangerous. As with so many problems we are seeing lately -- environmental or health -- factory farmed meat seems to be a big part of the cause. A graduate of the Cornell University School of Agriculture and the Tufts University School of Medicine, Michael Greger, M.D., serves as Director of Public Health and Animal Agriculture at The Humane Society of the United States. An internationally recognized lecturer, he has presented at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, and was an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial. His recent scientific publications in American Journal of Preventive Medicine, Biosecurity and Bioterrorism, Critical Reviews in Microbiology, and the International Journal of Food Safety, Nutrition, and Public Health explore the public health implications of industrialized animal agriculture.

Kathy Freston: How likely are we to have a bird or swine flu that turns into something really deadly and widespread?

Michael Greger: Unfortunately we don't know enough about the biology of these viruses to make accurate predictions, but influenza is definitely the disease to keep an eye on. AIDS has killed millions but is only fluid-borne. Malaria has killed millions but is relatively restricted to equatorial regions. Flu viruses are the only known pathogen capable of infecting literally billions of people in a matter of months. Right now we are in the midst of a flu pandemic caused by the swine-origin influenza virus H1N1. Millions of people have become infected and thousands have died, but H1N1 is not particularly virulent. There are other flu viruses that have emerged in recent decades such as the highly "pathogenic" (disease-causing) bird flu H5N1 that may have the potential to cause much greater human harm.

KF: What kind of damage could it do in terms of population mortality?

MG: Currently H5N1 kills approximately 60% of those it infects, so you don't even get a coin toss chance of survival. That's a mortality rate on par with some strains of Ebola. Thankfully, only a few hundred people have become infected. Should a virus like H5N1 trigger a pandemic, though, the results could be catastrophic. During a pandemic as many as 2 or 3 billion people can become infected. A 60% mortality rate is simply unimaginable. Unfortunately, it's not as far-fetched as it sounds. Both China and Indonesia have reported sporadic outbreaks of the H5N1 bird flu in pigs and sporadic outbreaks of the new pandemic virus H1N1 in pigs as well. Should a pig become co-infected with both strains, a hybrid mutant could theoretically arise with human transmissibility of swine flu and the human lethality of bird flu. That's the kind of nightmare scenario that keeps virologists up at night.

KF: How does a virus like that kill? What does it do to the body?

MG: Most often it starts with standard flu-like symptoms--fever, cough, and muscle aches. Instead of just infecting the respiratory tract, though, H5N1 may spread throughout the body and infect the brain, for example, leaving victims in a coma. Other early symptoms atypical of regular seasonal flu include vomiting, diarrhea, abdominal pain, chest pain, and bleeding from the nose and gums. Death is usually from acute fulminant respiratory distress, in which one basically drowns in one's own blood-tinted respiratory secretions.

Most of the damage is actually done by one's own immune system. H5N1 seems to trigger a "cytokine storm," an overexuberant immune reaction to the virus. These cytokine chemical messengers set off such a massive inflammatory reaction that on autopsy the lungs of victims may be virus-free, meaning that your body wins, but in burning down the village in order to save it you may not live through the process. In fact the reason why young people may be so vulnerable is because they have the strongest immune systems, and it's one's immune system that may kill you.

KF: How easy is it to contract the virus once it's in full swing?

MG: Catching a pandemic flu virus is essentially as easy as catching the regular seasonal flu. During a flu pandemic about 1 in 5 people may fall ill, but there are certainly ways to minimize one's risk via hand-washing and social distancing techniques. In a really severe pandemic, though, the advice would be to "shelter-in-place," isolating oneself and one's family in one's home until the danger passes. During such a pandemic the Department of Homeland Security uses as a key planning assumption that the American population would be asked to self-quarantine for up to 90 days per wave of the pandemic.

KF: Why do we have this potential disaster on our hands?

MG: The industrialization of the chicken and pork industries is thought to have wrought these unprecedented changes in avian and swine influenza. No one even got sick from bird flu for eight decades before a new strain, H5N1, started killing children in 1997. Likewise, in pigs here in the U.S. swine flu was totally stable for 8 decades before a pig-bird-human hybrid mutant virus appeared in commercial pig populations in 1998. It was that strain that combined with a Eurasian swine flu virus ten years later to spawn the flu pandemic of 2009, sickening millions of young people around the world.

The first hybrid mutant swine flu virus discovered in the United States was at a factory farm in North Carolina in which thousands of pregnant sows were confined in "gestation crates," veal crate-like metal stalls barely larger than their bodies. These kind of stressful, filthy, overcrowded conditions can provide a breeding ground for the emergence and spread of new diseases.

So far, only thousands of people have died from swine flu. Unless we radically change the way chickens and pigs are raised for food, though, it may only be a matter of time before a catastrophic pandemic arises.

KF: If factory farms are to blame, why have there been plagues and flu's throughout time, when factory farms were not around?

MG: Before the domestication of birds about 2,500 years ago, human influenza likely didn't even exist. Similarly, before the domestication of livestock there was no measles, small pox, and many other diseases that have plagued humanity since they were born in the barnyard about 10,000 years ago. Once diseases jump the species barrier from the animal kingdom, they can spread independently throughout human populations with often tragic consequences.

The worst plague in human history was the 1918 flu pandemic triggered by a bird flu virus that went on to kill upwards of 50 million people. The crowded, stressful, unhygienic trench warfare conditions during World War I that led to the emergence of the 1918 virus are replicated today in nearly every industrial chicken shed and egg operation. Instead of millions of vulnerable hosts to evolve within back then, we now have billions of chickens intensively confined in factory farms, arguably the Perfect Storm environment for the emergence and spread of hypervirulent, so-called "predator-type" viruses like H5N1. The 1918 virus killed about 2.5% of the people it infected, 20 times deadlier than the seasonal flu. H5N1 is now killing 60% of infected people, 20 times deadlier than the 1918 virus. So if a virus like 1918 gained easy human transmissibility, it could make the 1918 pandemic--the deadliest plague ever--look like the regular flu.

KF: Does handling or eating chicken or pork increase the chances of contracting the virus?

MG: There are certainly lots of viruses people can pick up from handling fresh meat, such as those that cause unpleasant conditions like contagious pustular dermatitis and a well-defined medical condition known as "butcher's warts." Even the wives of butchers appear to be at higher risk for cervical cancer, a cancer definitively associated with wart virus exposure. Cooking can destroy the flu virus, but the same can be said for all the bugs that sicken 76 million Americans a year. The problem is that people can cross-contaminate kitchen surfaces with fresh or frozen meat before pathogens have been cooked to death. There have been a number of cases of human influenza linked to the consumption of poultry products, but it's not clear whether swine flu viruses get into the meat. Regardless, the primary risk is not in the meat, but how meat is produced. Once a new disease is spawned from factory farm conditions it may be able spread person to person, and at that point animals--live or dead--may be out of the picture.

KF: How do we stave off this viral apocalypse?

MG: We need to give these animals more breathing room. The Pew Commission on Industrial Farm Animal Production, which included a former U.S. Secretary of Agriculture, concluded that industrialized animal agriculture posed "unacceptable" public health risks and called for gestation crates for pigs to be banned as they're already doing in Europe, noting that "[p]ractices that restrict natural motion, such as sow gestation crates, induce high levels of stress in the animals and threaten their health, which in turn may threaten human health."

Studies have shown that measures as simple as providing straw for pigs so they don't have the immune-crippling stress of living on bare concrete their whole lives can significantly cut down on swine flu transmission rates. Such a minimal act--providing straw--yet we often deny these animals even this modicum of mercy, both to their detriment and, potentially, to ours as well.

The American Public Health Association, the largest organization of public health professionals in the world, has called for a moratorium on factory farms. In fact the APHA journal, the American Journal of Public Health, published an editorial going beyond just calling for an end to factory farms. It questioned the prudence of raising so many animals in the first place: "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 are eaten--is largely off the radar as a significant preventive measure. Such a change, if sufficiently adopted or imposed, could still reduce the chances of the much-feared influenza epidemic. It would be even more likely to prevent unknown future diseases that, in the absence of this change, may result from farming animals intensively and from killing them for food. Yet humanity does not consider this option....Those who consume animals not only harm those animals and endanger themselves, but they also threaten the well-being of other humans who currently or will later inhabit the planet....[I]t 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."

KF: That is a pretty stunning statement! I know people will wonder...."If we give up animal protein, will our immune system be compromised... or will it be enhanced?"

MG: We've known for 20 years that the immune function of those eating vegetarian may be superior to those eating meat. First published in 1989, researchers at the German Cancer Research Center found that although vegetarians had the same number of disease-fighting white blood cells compared to meat eaters, the immune cells of vegetarians were twice as effective in destroying their targets--not only cancer cells, but virus-infected cells as well. So a more plant-based diet may protect both now and in the future against animal-borne diseases like pandemic influenza.

KF: This has been a real awakening. For more information on how to move toward a plant-based, vegan diet, check out my guide to conscious eating on HuffPost.