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SPEAKER: This is a production of Cornell University.
[APPLAUSE]
ALEXANDER TRAVIS: Well, thanks very much Joel for having me included. And my title, "A Central Role For Veterinarians in Sustaining Life on Earth" and that sounds pretty grandiose, right? But it's really absolutely true. And the philosophy of One Health captures that. So what exactly is One Health?
We've had an excellent introduction in the keynote address this morning, but the concept of One Health includes many, many different parts. And the different organizations really emphasize different aspects of that. The concept goes back for literally thousands of years to Hippocrates, that human health does depend on the health of the environment.
And then you've seen some of these more recent quotes from Virchow, the defining and creation of the field of veterinary public health by James Steele. The coining of the term One Medicine, and then more recently Billy Karesh's use of the term One Health, which really I think was the trigger at bringing this to the fore of public's attention and setting off a series of meetings that included one in New York City in the publication of the Manhattan Principles that really did tie sustainability into One Health.
Yet again, different organizations have different perspectives on this. And the One Health Initiative, you'll see I've highlighted, really focuses heavily on cross species disease transmission. In Europe, the Health and the Environment Alliance focuses on environmental contaminants and environmental change and how that influences health.
And another organization that uses the same acronym of HEAL, for Health and Ecosystems Analysis of Linkages, focuses on ecosystem integrity and particularly biodiversity. So what exactly is One Health again? Well, it's the simple philosophy that the health of all living things is connected. And I'd like to share or talk about several components that I think make up this and really help us expand the paradigm between some of the focus areas that different groups use.
And the first is the one really that you heard the most about so far and that's comparative medicine. Different animals can function as models for human disease and also treatments that are designed for human medicine can be translated to veterinary medicine and vice versa. Next is the one that comes to mind for most people, which is transmission of disease.
And really this triangular interface between humans, agricultural species and domestic animals, and wildlife with diseases moving in between all three corners of this triangle. The next two really are areas that are more central to sustainability. And that is shared vulnerability to changes in the environment. That is humans and animals in the environment both respond to the changes.
These could be physical changes, such as climate change or the presence of a toxin in the environment, or biological change. The presence or emergence of a new pathogen, the change in geographic range of a arthropod vector of disease. And we both respond, both sets of populations respond to those changes.
The last point is the reliance or interconnectedness of human health and wellbeing on animals and the environment. And this is very broad stretching from mental health, nutrition, livelihoods, to really fundamentally human reliance on the ecosystems goods and services that animals in the environment provide.
Now, you'll notice that the sessions in this meeting, sustainability, genetics, cancer biology, infectious disease don't have a one-to-one correspondence with what I've outlined as the pillars of One Health. Rather each of these sessions includes all the aspects of One Health that I just described. You can't really separate them out.
But for our section on sustainability, I'll now in the next part of the talk focus on a few examples. But really sustainability is a word that's used in so many different ways these days that it does pay to take a few seconds to define it.
And the Brundtland Commission I think came up with the best definition of sustainable development from a human perspective, which is that it's development that meets the needs of the present without compromising the ability of future generations to meet their own needs. And that's very, very simple and very broad.
But one thing they've really left out is that we must include the preservation of ecosystems goods and services. And this is a theme that will come back again and again. That animals don't live in an ecosystem, animals are part of an ecosystem and serve vital functions in that. And if we lose them, then the system changes.
So if we are to truly preserve the ability of future generations to meet their needs, we have to preserve the ecosystems that exist now, so that they can use them in the future. So I'll give now a few sustainability examples of each of these core areas starting with comparative medicine.
And indeed, if you look at the online Mendelian Inheritance in Animals database there are literally hundreds of diseases, dogs, cats, cattle, where there's a direct genetic homologue between the disease in animals and the disease in people. But from a sustainability perspective, what about all the other species?
And this is a table that I've shortened and condensed to fit on this one slide, from the IUCN Red List, and it describes all the different vertebrate species. So mammals, birds, reptiles, amphibians, fish, and how many numbers or how many different species there are, how many we know about, and then how many of those, or what percentages, are actually threatened or endangered.
So if you look at something like mammals, very well studied, most mammals they have information about. Same with birds, but if you look at something like reptiles or fish we really know very, very little about most of those species. So it's hard to say what percentage of them are threatened. And that's really quite bad because it's the common species we tend to know about.
It's those species that are rare or difficult to study hard to get to that we know little about, but even for those that we know, the numbers are frightening. Between 21 to 36% of mammalian species are threatened with extinction. The number for amphibians is horrifying, 31 to 56%. And again, for those that we don't know about, the numbers could potentially even be worse.
Now this loss is so severe that it constitutes our planet's sixth global mass extinction crisis. And what's different about this mass extinction versus the others is that the others were physical in nature. Volcanism, asteroid hitting the Earth, things like that. This one has a biological cause and that's, of course, us.
So what kinds of things could we be learning from these species if we preserve them and if we save them for future generations? I'll give just a few quick examples. This is a frog, Rheobatrachus silus, and I don't know if you can make it out, but inside this frog's mouth is another little frog. It's not a cannibalism, it's not eating that frog.
Rather it is a gastric brooding organism. So there's two species, and this is one Rheobatrachus silus, where they ovulate, the eggs are fertilized, and then the female will eat those eggs and they turn off stomach acid secretion. Now, what could that teach us about control of GI function, and prostaglandins, and stomach acid secretion?
Well, we won't really know that because they went extinct within a few years after being found. There's actually an effort in Australia to resurrect them using cloning technologies, because of the potential power of that model. Now, we don't have to go to Australia to look for these kinds of examples of models.
Just go outside here and you'll find woodchucks. Woodchuck hepatitis virus is an outstanding natural model for human Hepatitis B, and in particular, the severe hepatitis and cancers that will develop as a result of that. And this has been a model that's been used for several decades.
A more recent disease is that seen in Tasmanian Devils, which have a transmissible form of cancer that they literally transmit to each other by biting or scratching each other. What could that teach us about immunomodulation by invasive cancer cells? What could that teach us about the underlying genetic susceptibility?
Well, this is a disease that's quite new and actually threatens the Tasmanian Devil with extinction and there's a number of conservation efforts that are currently underway to try to prevent that. And a number of studies are being done about this, but sometimes when I give this example, people say, well, there's really not good examples of transmissible cancer in humans.
Well, there weren't examples of this until a few years ago in Tasmanian Devils either. So can we learn from things that exist in nature from these naturally occurring models while we have the opportunity? And it's our duty really to conserve those for future generations.
Now again, the most common linkage in terms of One Health and sustainability is that typically of infectious disease. And when we think about zoonoses and infectious disease, it's often emergent disease that we concentrate on. And that's something that's either literally a new pathogen or something that is new to an area, spreading its geographic range, or changing in some way, perhaps jumping from one species to another.
These are found not just in tropical jungles, but literally all over the world. And you saw a slide similar to this this morning. Europe, United States, the Northeast in particular, where there's a lot of traffic movement of people that's often where people literally are vectors for moving the disease, whether it's physically on ourselves or in our airplanes, boats, ballast, water, and whatnot.
Now the archetype of an infectious disease, an emerging infectious disease that relies or has sustainability issues at its core is that of Nipah virus. Henipaviruses are a genus of paramyxoviruses and have caused the death of several hundred people and the culling of over a million pigs and the loss of multiple hundreds of millions of dollars in agricultural and economic costs.
And it really comes from a central issue of deforestation. As farmers encroached upon and moved into rainforest areas, they caused a migration or a movement of pteropus bat species-- these are the large flying foxes, the fruit bats-- that then had to go elsewhere to find fruiting trees which to eat.
They found them in the orchards that farmers were now beginning to plant in those deforested areas and that was an ideal opportunity for pigs to come into contact with their droppings, dropped pieces of fruit, and that caused the infection that then spread into people and led to enormous social and political consequences.
Now you don't really need the pig though as an intermediate. It's found now that Nipah viruses are being transmitted from human practices of collecting palm sap. And the bats feed there at night and then the contaminated material is actually sold fresh in markets. So a local example, a more local example of how biodiversity affects disease transmission is that in Lyme disease.
Healthier patches of forest, larger patches of forest have more larger animals, mesopredators, things like opossums, for example. And these are less good hosts for pathogens that give Lyme disease, the pathogen that gives Lyme disease, and also for the ticks.
So what this figure shows is that in forests that have opossums, there's relatively few ticks per hectare if we look at that green circle in comparison to patches that don't have opossums, where there are a lot more mice and more ticks. What's really remarkable about this, though, is the yellow in the circle refers to the ticks that are infected with the Borrelia.
And in here you see how small the yellow is. So it's not just that there are fewer ticks, but there are fewer infected ticks when you have a more biodiverse forest. There's been a recent review on this last year in PNAS, Sam Myers and Steve Osofsky, detailing numbers and numbers and numbers of examples, Schistosomiasis, hantavirus, Chagas Disease, where changes in the ecosystem directly affect transmission to people.
Now it's not just how these animals, again, are living, but how people use those resources as well. Whether it's bushmeat, which is something where people get a lot of animal source foods, income, but can definitely be a major cause of defaunation and extinction. But also how they sell pets and meat. Live animal markets.
And you can make out, there's lorises right next to reptiles, chickens right next to ducks. These are ideal ways. You couldn't think of a better way to make a disease move among species than stressing animals out, not giving them adequate food and water, having them stared at by large numbers of giant predators, people walking by, and then we wonder why there are public health consequences.
So really from a regulatory perspective this is a major area that needs to be dealt with around the world. And again, it happens in the United States as well as elsewhere. Shared vulnerability to changes in the environment. Well, in terms of climate change, the more data that come out we realize things are far worse than were initially modeled.
Most of the modeling is done on 95% confidence interval and it turns out that things are actually worse in terms of loss of ice. The poster child, if you will, the polar bear, we know how that affects their ability to hunt and survive. But changes in temperature affect us.
If looking at a map of North America, predictions in changes in temperature, dengue, Boston, Montreal, these will soon become areas where it is endemic most likely without significant public health interventions. And this is going to put really enormous strain on city and regional public health departments that aren't right now equipped to deal with these kinds of diseases.
Climate change isn't just about temperature, it's about precipitation, it's about water, amounts, patterns of precipitation. This is a picture from Kenya, where there have been a number of significant droughts. And what you see in this picture is really quite interesting. You see a herder pastoral grazing of livestock bringing them into a national park to gain access to water.
And in the background you can see elephants. And what's been shown repeatedly in a number of different countries is that national parks, conserved spaces, actually make for healthier, more economically resilient human populations in the areas around them, because when times get tough, they can then rely on those natural resources that have been conserved.
And this is in opposition to forests that are designated for community use, where, often, there's, unfortunately, the tragedy of the commons, where if people aren't sure how long those resources are going to last, whether the governance policies are going to change. People say, well, I want to get mine now and they use them up very quickly.
So this has long been a debate in social science whether national parks actually helped make people poorer by preventing them from gaining access to resources. And the more recent data, again, from many places, says that's actually the exact opposite.
Here we see another picture of the beluga. And it's not just diseases or disorders of mental health. Belugas have been the subject of a very fascinating study on environmental toxins. Martineau et al did necropsies on 129 belugas in the Saint Lawrence estuary and found cancer rate of 27%.
That's similar to people, it's similar to domestic animals, veterinary practices. But if you look at the Arctic population of belugas, they looked at 50 animals and found no cancer. And this is a cancer rate far higher than that's found in any other cetacean species. So we are contaminating not just ourselves, but also the animals that share our environment.
And in the case of the beluga, it's most likely polycyclic aromatic hydrocarbons from aluminum smelters in the area. And that brings us then to the last component, which is really that network of linkages, the ways that humans rely on animal health and the ecosystems goods and services that they provide.
The classic example is, of course, that of bees, that pollinate our food crops, trees, flowering crops, different things. And they are dying out due to colony collapse disorder, components of which could be parasitic infectious as well as pesticides and toxins. And the honeybees we have in this area are an introduced species.
And now we are going back and trying to figure out if the native bees that were already here and are not as susceptible to some of these agents causing colony collapse disorder, whether those native bees can actually resume those functions and serve those roles. In some parts of the world where there are heavier pesticide exposures, people literally with paint brushes have to go through and pollinate the flowers on the trees to get fruit.
Obviously, very labor intensive, economically at great cost. And so let's preserve these kinds of insect resources as well. I've given mostly terrestrial examples. But the same situation in connections hold true in marine environments. Climate change certainly affecting the health of corals, which are the keystone of the most biodiverse marine habitats.
And they're not just being affected by the change in water temperature, not just being affected by the change in ocean water pH, but also from human practices such as the dumping of effluent, whether it's human waste, runoff from farms, aquaculture waste, heavy nutrient loads from aquaculture.
And what that does is it makes the corals more susceptible to disease. And this is, I think, a very important area that's really just beginning to be studied in the past decade or so. Now, just last week there was a special feature in "Science" that had a number of papers on defaunation, the loss of animals. What's being done about that.
And this, I think just made a very, very simple point. We're not just talking about extinction. That is not the only bad thing that's happening. Defaunation is probably a better term because it also encompasses the reduction in numbers of animals and the loss of biodiversity in patchy habitats.
And they had a number of different diagrams showing ecosystems goods and services. And I'll make this point again, animals don't live in an ecosystem. They are part of that ecosystem and providing functions. If we lose them, the system changes, and we lose then the goods and services that we rely upon.
I'll change gears very slightly and show this picture, and I won't because of the time constraint ask you questions about it, but usually when I'm teaching or giving a seminar, I'll say, what do you think this picture shows? And invariably the answer is slash and burn agriculture, which is probably a good guess.
You've got a fire, you've got a young man holding a hoe, but what they are really doing is hunting. And this is an area in Zambia where we work. Our surveys show about 94% of the families are food insecure. That means they don't have enough food to feed all the members of their family, at least for during one month of the year.
And what the children do is if they find a rat or mouse burrow, they'll set the field on fire and then wait by the burrow, because the animals will run to the burrow to escape the fire. And then you see the young man clobbering them with the hoe, and now there's an animal source food.
So I was doing some surveys and talking to the farmers, and again, desperate poverty, desperate food insecurity, and these fields are right next to the villages, right next to their farm crops. And I said, do you ever lose some of your maize or your crops? And it's like oh, yeah, you know, and maybe 5%, some small amount.
But even given the hunger that's there, they recognize the need for animal source food for their children to develop. Now the impacts of this are very wide ranging. The footpaths, which you see up here, are very narrow. These are the only firebreaks that are available. And oftentimes the fires jump and they jump in both directions.
You'll see a lot of the thatched roofs on people's homes. We'll have fire damage, but also these often become large bush fires. And so when we think about how bad cattle are from intensive greenhouse gas thing, and you see all these quotes and figures how much carbon does it take to get a gallon of milk or a pound of beef.
But what's the carbon footprint of that mouse or rat that's captured in the face of these kinds of bush fires? And we need to look at these things from different contexts, which is not just the carbon footprint of that. But what is the nutritional content of what they're getting? And then base some of these comparisons on actual the nutritional content.
Now that's not at all to say that we are raising cattle perfectly in many parts of the world. They are causing massive amounts of deforestation, not just for pasture land, but for growing food crops specifically to feed them. And so this can and must be done better. But the division between intensive and extensive livestock systems really depends completely on where you are and how you do it.
And this is a major area for veterinary medicine to come back to and embrace as being a core component of sustainability and One Health, is food production. Now, unfortunately, iron deficiency anemia is the most prevalent nutritional disorder. 50% of pregnant women, 40% of preschool children.
It affects health, cognitive development, national productivity. Meat iron is highly bioavailable, but it's more than just that. And going back decades in the literature, the other substances, what was called a meat factor, it's not just protein, it's not just calories, it's not just iron. There are micronutrients there that are also critically important.
And a study in Kenya on children where they supplemented diets with different amounts of protein and calories coming from meat or other sources, found that the meat actually did improve cognitive development, school test scores, physical activity, initiative behaviors, muscle mass. It had multiple impacts.
This is not the amount of a giant Western hamburger, a pound of beef. This is a bite or two out of that, that can convey these kinds of benefits. Livestock really produced diverse contributions. It's not just milk and meat. It's traction, fuel, they act as an economic savings account. People buy livestock, which will last for a while in areas where there's not banking.
And unfortunately in many parts of the world, because cropping is more profitable, there's a giant push to get people away from livestock and do more cropping. And unfortunately with climate change, people have modeled in all these areas you see in Africa in red, they're going to have to stop cropping and go back to pastoralism and raising livestock, because there's not going to be sufficient rainfall.
Who's going to provide the veterinary infrastructure if it's lost in those countries? Now livestock are more than just ruminants. In the past few decades, there's been a tremendous explosion in the need and production of poultry. And Asia, most of it is taking place with large-scale commercial farms.
But again, in many rural developing parts of the world, backyard birds are the key to One Health. When we started working in Zambia, we found that between 50 to 100% of the village's birds would die before sale or safe consumption. Between 50 to 100%. So everybody raised the chickens, but they didn't really expect to get much out of them.
If they lived it was great, if they didn't, eh. They didn't feed them, didn't water them, but it was something that they knew would be good if they could just get it to work. Now unfortunately what they did at night was they brought the birds into their homes to keep them safe from predators.
And if highly pathogenic avian influenza ever goes in, that's exactly what you don't want to do. So we help them really set up elevated stick roosts, which not only are better for the birds and better for the people, but really kept them safer from predators as well. We helped them set up community vaccination programs for Newcastle disease.
And after a few fits and starts in the first year or two, now flock sizes have stabilized at double to triple the level that they were. And so if you just look at metrics of production, you think, oh great, we solved a nutritional problem, right? Well, not at all. What we found was that nobody was eating the birds.
Now that they could count on them, they wanted to sell them and send their kids to school. And in an area with an average of four years education, this is not a bad problem to try to solve, but it wasn't at all what we had initially thought about.
So a vet student, Sarah Dumas, who actually spent about six months in Zambia while she was here at Cornell, then did an internship at Illinois and has now come back for a PhD in sustainable food production and also the effects on human maternal health and child development, she has helped them set up a series of small-scale egg layer facilities.
And from our pilots, we found an increase in income for the cooperatives. A net income was 44% and an increase of 96% in egg consumption in those villages. But is that enough to achieve those benefits in child health and development? And that's what she's doing her PhD about.
So in this period of great change and great challenges with sustainability, with One Health, are there really great opportunities for you? And you've already been described as the future of Veterinary Medicine. And what are our roles as veterinarians, as scientists? What are we going to do in response to these challenges, or do we just give up?
We just say, oh, too hard. I'm just going to put my head down and do my thing. And I would really encourage you that, no, when you get back home put on your supervet costume, right? We need you. And in the course of this meeting, I want you to get excited by all the cool things that you are going to see and hear.
All the problems that need to be solved. And then equally, I want you to help other people get excited about the research you are doing during the summers at your posters and think about them the impacts that you can have on human and animal health. I'll close just with a slide for roles for veterinarians and scientists in One Health this is a common question about careers.
Biomedical models for human disease, wildlife conservation, either as saving models or to restore or retain ecosystem functions. This interface of agricultural animals, domestic animals and people, environmental monitoring, policy, government, hugely important. We have to have people who know what they're talking about making decisions, and then education and good citizenship. And with that, I'll thank you.
[APPLAUSE]
SPEAKER: This has been a production of Cornell University on the web at cornell.edu.
Cornell's Alexander Travis defines different components of the One Health initiative to attain optimal health for people, animals and the environment, and illustrates ways veterinary clinician-scientists can tackle pressing health issues. The Aug. 1 talk was part of the 2014 Merial-NIH Veterinary Scholars Symposium at Cornell, which focused on veterinary medicine's key role in sustainability, genetics, cancer biology and infectious disease.
Travis is an associate professor of reproductive biology and wildlife conservation and Faculty Director for the Environment at Cornell's Atkinson Center for a Sustainable Future. He also heads Cornell's Center for Wildlife Conservation.
