Interview with Dr. William Karesh
Dr. William Karesh heads the Field Veterinary Program of the Wildlife Conservation Society, which has more than 300 field projects in more than 50 countries around the world. He helped launch the “One World, One Health” initiative, which aims to bring together experts from various scientific and medical disciplines to tackle emerging threats. Here, he talks with FRONTLINE/World’s Serene Fang about the increasing threat to humans of zoonotic diseases, examples of how outbreaks happen, and new techniques to deal with these new threats.
FRONTLINE/World: What are zoonotic diseases?
Dr. William Karesh: In the broadest terms, we use “zoonotic disease” to mean an infectious organism that can move between people and animals. And in some ways, we use it to mean a disease that can move in both directions. A lot of people limit it to diseases people can get from animals, but they really go both ways: Animals can get human diseases, and humans can get animal diseases. The fact is, the diseases don’t really care.
Why are zoonotic diseases getting so much attention lately?
I think the medical field is just relearning what we knew thousands of years ago. There was always an understanding, back in Roman times, in Greek times, and so forth -- people knew that they could get diseases from their animals. And in the 1950s and 60s and 70s, because of the effectiveness of antibiotics, we stopped seeing a lot of infections in people, and medicine shifted to cardiology and oncology and other fields that didn’t relate. So I think we kind of forgot about this relationship with infectious diseases, and now we’re seeing a resurgence of them. As human populations grow, as global travel becomes easier, we start to see more diseases.
What part do zoonotic diseases play in the overall landscape of emerging infectious diseases?
If we look at wildlife, if we look at diseases in animals, we can start to understand and predict somewhat what might be the next emerging disease. Also [it helps] to change our behavior in terms of how we’re getting those diseases. So the wildlife market, the bushmeat trade, the handling, the international trade in wildlife -- all predispose us to getting these new emerging diseases.
Can you give us some examples of how zoonotic outbreaks happen?
Well, we have things like rabies -- which we take for granted in the United States because we vaccinate our pets and we don’t come in contact with bats very often. But in parts of the world that are very poor, for example in India, 40 to 50,000 people are dying from rabies every year. So this is a kind of global disease that affects different populations very differently.
And HIV/AIDS is a very different story. It’s about people in one part of the world that have this practice of hunting monkeys and handling them, and this virus jumped between monkeys and people through the handling, and then spread from people all through the world. So the HIV/AIDS crisis was caused by a few small incidents in Africa, and it has become a global pandemic.
And then you have very sudden jumps like we saw with bird flu, avian influenza, which is really a product of domestic poultry being raised improperly in part of the world, in Asia, and leaking in to people and then spreading, although slowly. So we have these different mechanisms for how these diseases can affect us.
What are some factors of modern life that contribute to the emergence and spread of zoonotic diseases?
I think [it’s] this contact between people and wildlife in particular, because contact with domestic animals has been going on for thousands of years, so there’s probably a much lower risk of emergence from domestic animals -- cats, dogs, cows, horses. Really, [it’s] this whole world of wildlife, where people are going into pristine forests; logging companies are cutting down trees, building roads into the forests. They’re building a highway across the Amazon. So we’re encroaching on these new areas, coming into contact with new infectious diseases that are in these animals. There’s also a huge trade in wildlife. Billions of animals are captured alive and moved to markets and handled by people, and that handling is how we get infected. So the wildlife trade is a huge driver, and then the disease spreads around the world because of rapid transportation. It used to take months to travel around the world. You got sick and you got better, or you got sick and you died. Now, you can get on an airplane and be around the world in ten or 12 hours.
What can the human health and medical community learn from wildlife health experts?
What we’ve been doing at the Wildlife Conservation Society for the last 20 years is looking at infectious diseases in wildlife. Of course, we’re concerned about the health of the wildlife because that’s our job. But what we’ve learned over the years is that all the same diseases that we were dealing with in the wildlife were the same as the ones we were dealing with in people living in the surrounding areas or in their animals. So when we say that there’s human health or livestock health or wildlife health, we just made that up. There’s only one health. That’s how we got this concept of One Health. And with global movement of people and animals, there’s clearly just one world. So this concept of One World, One Health is an understanding that we just share all these diseases and we just share this one planet, and that by working together, if we can work together -- the veterinary community, the ecology community, the environmental community, and the public health community -- we can really help each other and reduce the burden of disease.
What is One World, One Health?
One World, One Health clicked on for me 20 years ago, when we were starting to work with great apes in Africa -- and even before that, when I worked with great apes in zoos. In the zoos, we knew that every year the apes were very prone to getting what looked like respiratory infections, cold or flu, from humans. Because where else would they get it from? From people coming to the zoo. When we looked in the wild, we started to see that orangutans in Indonesia were getting tuberculosis from humans. We realized that the animals that we were supposed to be protecting were getting these human diseases. So what’s the best way to protect gorillas in Africa from getting measles, or getting influenza or other human diseases? Well, if people were healthier there, the gorillas would be safe. So maybe we should be encouraging health care programs for villagers that vaccinate people, to protect the wildlife. It’s very difficult to vaccinate wildlife. In some cases, it’s possible, but it’s challenging. It’s much easier to vaccinate people, and it’s of great benefit to them.
So you see, that’s kind of the beginning of this One Health concept. We wanted to work upstream. If animals are the source of a disease, we want to break the chain to prevent people from getting it. If people are the source of disease, we need to break the chain going in the animal direction.
What’s standing in the way of this vision?
I think culturally, in our training, we’re taught that we’re supposed to know everything ourselves. In the medical field, I prepared to exit school and instill confidence in people so that when I tell them what to do, give them medical advice, they believe me and trust me. We are trained to believe that we actually know most of what we need to know. We have a cultural bias in the medical field that we don’t need a tremendous amount of input before we make a decision. And that works 99 percent of the time. It’s a really efficient way to approach health care.
But we’re not programmed to take the time to gather tremendous amounts of input for complex [situations]. I think we’re seeing that shift now in the last four or five years. All of us in the medical field are starting to understand that the toughest problems need more engagement from more people. A medical problem is also an ecological problem and an economic problem, and it’s a social and anthropologic problem. With all those experts playing a role, that’s really what becomes the One Health approach.
Have veterinarians been part of the solution in dealing with human health issues?
I think the separation between veterinary medicine and human medicine has been growing over the years. There was always public health in veterinary medicine, but it was kind of moved off to the side. But it all circles back, and now we’re all connected with these infectious diseases. We used to joke; you know that old cliché, “Think outside the box”? What’s happened over the years is that all these microbes ate the box. We don’t even have to bother thinking outside the box. The box is gone. We live in this world, and it’s all interconnected. We’re realizing these infectious diseases really don’t care about our taxonomy, our species divisions. They just move around anywhere they want.
What needs to be done to make One Health work?
We really need to invest serious money in helping the developing world have better education, better hygiene, better access to clean water. It doesn’t sound very sexy, but a real driver of disease is poverty. So we really cannot ignore that. The next level up, we need to start tackling these points of contact. So we see HIV/AIDS and SARS that all came from wildlife. How do you deal with that? Well, we really need to be educating local people about the risks. We need to better regulate markets. Billions of wild animals are sold every year in Southeast Asia in markets. They’re brought in from the wild; there’s no control over the diseases they have; they’re mixed with chickens and ducks and pigs and people and then sold. People take them home and kill them and get blood on their hands, and they get infected. So we need to either better regulate those markets, close those markets, or teach people about good hygiene. Washing your hands. Cooking your food. We’re going to have fewer emerging diseases if we do that.
How do you control these diseases?
Well, there are two approaches. One is to try to prevent them; that’s working upstream. So when we work with wildlife in the forest, we’re talking about upstream prevention of diseases getting into people, and when we work with people in the forest, we want to have them healthy so they don’t give diseases to wildlife. We want them to vaccinate their cows and sheep and goats, so vaccination is a prevention step.
If that doesn’t work, medication is the backup plan for the sick ones. We can develop new drugs to prevent and treat disease. For influenza, we have a few drugs. You can take them and they will shorten the time and reduce the mortality. But that’s far more expensive than reducing the number of people actually getting influenza. We can reduce flu by getting vaccinations to people that have access, but we’ll probably never reduce the reality of influenzas circulating the planet. It’s just so common.
Could we reduce the chance of the next new disease? Probably, because we know those are coming from these live wildlife markets. By closing those markets or regulating those markets, we could actually reduce the chance of those new diseases coming out. Rather than try to develop a drug for SARS or a vaccine for SARS, we can actually try to prevent the SARS-type outbreaks from happening if we did a better job of controlling how we interact with wildlife.
Can you put the work of Gladys Kalema-Zikusoka, one of the characters from our film, in the One World, One Health context for us?
Gladys’ work in the Conservation Through Public Health organization that she started is really a great example of how this ties together. We can have lots of international meetings (and we do, all the time -- One World, One Health has been adopted by the United Nations and the World Bank) but until you get it on the ground, like Gladys is doing, it doesn’t really mean anything. That’s really where the action occurs. It’s working with local villagers and educating them, making sure they get some basic health care. And taking care of their livestock will ensure that they have a little more to eat, but it also reduces the risk of them getting diseases from their animals, and it protects wildlife from getting diseases from their animals. So it’s win, win, win.
Now, why can’t we get more of that done? Because it doesn’t fit into the traditional agency model. The agriculture group says, “That’s not my job; my mandate is just for the livestock.” And the human health people say, “That’s not my job.” And the wildlife health people traditionally say, “That’s not my job.” And none of them, probably, have enough money to do everyone else’s work.
The other challenge is that you’re living in an area with probably only 200 or 300 or 400 people. The big health foundations want the biggest bang for their buck. You see the big campaigns for malaria and AIDS and TB; they’re going to go to the big urban areas, because it doesn’t cost them more to be there than to be in a village. In a village, they only reach 200 or 300 people. In an urban area, they might reach a million people. So you can’t really blame them for wanting to use their money in an urban area, but it leaves this frontier, this fringe. People on the edge of society, the people that are in most contact with wildlife, that live the closest to animals, they get the poorest health care in the world. Because they’re not in these urban areas, they’re beyond the reach of normal health care.
So you have someone like Gladys who says, “Well, I’m here; I should do something.” And I think that she’s doing a great job. Now for someone to say, “She’s a veterinarian; she shouldn’t be doing that,” -- well, a lot of health care workers aren’t doctors at all. We train them to be health care workers, and that’s a great profession. It doesn’t really take an infectious disease expert to be in a village to help people improve their lives.
How did you come know and support Gladys’ work?
We have a program, the Wildlife Conservation Society, where we find young professionals that are doing really innovative work. We think they have a lot of potential, so we support their activities in the field, to get them started. We want the best and the brightest out in the field doing the kind of work she’s doing. And then we’ll support them with seed money to get them started. She’s been very successful from there. With that seed money, she has grown to a really great program.
What is it about her that makes her successful?
She’s smart, but there are lots of smart people. She’s very passionate about what she’s doing, but there are a lot of passionate people out there, too. And she has a very good skill at explaining to people why what she cares about matters and that what she’s doing can be done. That’s a great combination, when you have those three things: intelligence, passion, and an ability to communicate your story. And I think that’s worked very well to make her successful.