Memories of West Nile Virus, Mad Cow Disease and SARS are still fresh, even after reports of the initial outbreaks have long faded. Author Mark Jerome Walters believes we should look to our own actions for the origins of these diseases. Host Steve Curwood talks with Walters about his new book, "Six Modern Plagues and How We Are Causing Them."
CURWOOD: From the cattle carcasses of mad cow disease to the surgical masks of SARS, it’s hard to forget the images of the world’s modern epidemics. International labs are trying to find the biological origins of these fast-spreading and, in many cases, deadly diseases. But Mark Jerome Walters says that, in part, we are to blame for the scourge. Dr. Walters is a Florida-based journalist trained in veterinary medicine and he’s written a new book about the human impact on emerging diseases. It’s called “Six Modern Plagues and How We Are Causing Them,” and he joins me now. Welcome, Mark.
WALTERS: Thank you.
CURWOOD: Mark, in your book you coin the term “ecodemic.” Could you explain what this is?
WALTERS: We have traditionally used the term “epidemics” or “pandemics” to describe diseases. And the more I learned about these the more I came to realize the profound human hand in the emergence and spread of these diseases. And it seemed to me that we were just too often letting ourselves off the hook by calling them kind of a dispassionate, distant epidemics. And I coined the term “ecodemics,” number one, to honor the deep ecological roots of these diseases and also, in the hope of trying to shift some of the responsibility for these to human beings and away from nature.
CURWOOD: You write that epidemics historically come in waves, brought on, in part, by human activity. Can you trace some history of this for us, please?
WALTERS: When people first began to coalesce into settlements and to domesticate animals thousands of years ago, we really set up a situation where a number of diseases jumped to human beings. For example, you know, cattle were the original source of small pox. And we saw – it is widely believed that the common cold came from horses, measles from a mutant distemper virus in dogs. And even leprosy is believed to have arisen at this time. Five hundred years or so ago as the Europeans and others began exploring the globe, we know some of the stories about the terrible plagues that were introduced to the Americas, to the Pacific, to Hawaii, for example, and to Africa. Well, 150 years ago we saw that increased immunity and some medical advances had really brought a dramatic decline in infectious disease. But now, in the past 20 or 30 years, we have seen what is likely to be another great wave of epidemics.
CURWOOD: Can you give me just a brief rundown of the various human impacts that contribute to epidemics?
WALTERS: Sure. I think that industrialized agriculture is certainly one of the most significant. We’ve seen that in mad cow disease. And we also see an element of the industrialized agriculture affecting the spread of West Nile virus. One of the reasons that the outbreak was so severe, recently, in Colorado, where more than 40 people have died, is because a mosquito that carries it out there breeds very well in irrigation ditches that are used in the farmland out there. Forest degradation – that is well documented, its close ties with the emergence of Lyme disease which, after all, has become the most common disease in the United States spread by a vector, a tick. And in many of these we see the whole idea of globalization and rapid spread, whether it’s spreading salmonella through the distribution of cattle feed, or SARS, which was spread very quickly from Hong Kong through global travel on airplanes and elsewhere.
CURWOOD: What kind of diseases to you see coming in the wake of climate change?
WALTERS: We are probably apt to see a number of diseases spread because the climate changes and makes one area more hospitable than it was before. For example, with malaria which is appearing in new parts of the world and appearing in places where we thought we had had it completely eliminated. For example, in Virginia where not long ago it was found for the first time in twenty years in both people and mosquitoes.
CURWOOD: You mentioned salmonella. Tell us, why is it such a problem?
WALTERS: Salmonella – there is a long history of that causing food poisoning in people. And the interesting thing as new waves and different types of salmonella emerged – they seemed to follow the introduction of certain antibiotics into agriculture. And so we’ve had lessons time and time again. You use a certain class or family of drugs to treat animals, to help them grow faster, and within months or perhaps years you begin to see antibiotic resistant salmonella in people. And so it’s both the most recent form of salmonella, which is called DT104, emerged and it was resistant to five different of antibiotics and some of the most of the most powerful antibiotics we had on the market.
CURWOOD: Mark, what diseases do you see on the horizon where human impacts on the environment are to blame?
WALTERS: We see other viruses tooling around elsewhere in the world that have caused very few deaths but have the potential for something quite large. The nipah virus, for example, in Malaysia. Here’s a virus that was originally carried by bats and did not seem to affect humans or any other species. And bats, because they had carried it for so long, were essentially immune. Well, because of burning of forests and climatic events, and the failure of the natural fruit crop for these bats, they were forced to change their migration route. And that brought them to cultivated orchards where there were also a lot of pigs. Then they infected pigs; pigs apparently infected humans. Now, if that were to emerge in the U.S. it would be an enormous problem, both in terms of public health and economic. And I do know some epidemiologists – that is their disease they seem to fear most. And that is why I think there is an increasing trend to try to understand the ecological part of these diseases, and I think it’s tremendously encouraging when you see this new level of collaboration and sharing of knowledge. For example, ornithologists become as important in the equation of understanding a new human disease as an epidemiologist. That is progress, and that is bound to take us somewhere, in my view, much better than we have been.
CURWOOD: Mark Jerome Walters is a journalist and author of “Six Modern Plagues and How We Are Causing Them.” Thanks for taking this time with me today.
WALTERS: Thank you.
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