How Humans Are Facilitating More Disease 'Spillover'

In Spillover, science writer David Quammen explores the emergence of human diseases. He argues chains of infection are becoming more common. Host Rachel Martin speaks with Quammen about his new book.

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RACHEL MARTIN, HOST:

About 10 years ago, doctors in southern China started seeing a lot of patients with signs of what looked like a new illness.

DAVID QUAMMEN: It's like a very, very bad flu that gets people coughing and wheezing and with lung blockage.

MARTIN: That's David Quammen. He's a science writer who writes about the emergence of human diseases in his new book, "Spillover."

QUAMMEN: It causes a throbbing headache and a high fever. And then in some cases, if I recall correctly, it begins to cause organ shutdown, as well.

MARTIN: It spread quickly, passing on the drops of a sneeze or a cough - first just to a small cluster of people.

QUAMMEN: One of those was a doctor who then left southern China and went to a wedding of his nephew in Hong Kong.

MARTIN: Even though he was infected, the doctor felt well enough to travel.

QUAMMEN: He started getting sick as they arrived in Hong Kong. He stayed at the Metropole Hotel. He got sicker and sicker. And somehow, he passed this virus he was carrying, to other people, especially on the ninth floor. Maybe he was sneezing in the elevator, maybe he was sneezing in the corridor. And other people up and down that corridor became infected. And those were the people, who then, as tourists to Hong Kong, went home.

MARTIN: They boarded planes, flying across the globe.

QUAMMEN: They went home to Singapore. They went home to Toronto.

MARTIN: And the virus spread. It was early 2003. And suddenly, the rest of the world took notice.

UNIDENTIFIED MAN: Officials at the Centers for Disease Control and Prevention are looking at samples from a mysterious pneumonia-like illness...

UNIDENTIFIED WOMAN: At least 160 people have gotten sick...

LIANE HANSEN: At least a half-dozen deaths have been attributed to it.

ROB GIFFORD: The World Health Organization has named the illness Severe Acute Respiratory Syndrome.

MARTIN: Better known as SARS. In the end, about 8,000 people were infected. Around 800 died. But by the summer of 2003, the outbreak had been contained. David Quammen calls the public response to SARS, for the most part, a success.

QUAMMEN: SARS was a medium-sized outbreak that could've been a huge outbreak. We really dodged a bullet with SARS.

MARTIN: That made one question all the more important: where did SARS actually come from?

QUAMMEN: They traced it to a type of animal related to mongooses called the Himalayan Palm Civet, highly valued in the wild flavor restaurants of Southern China. So, people were going into restaurants and they were saying, oh, give me the Himalayan Palm Civet, and that seems to be how the first case picked up the virus.

MARTIN: But ultimately, scientists traced the virus even further down the chain of infection.

QUAMMEN: It is one or more species of bats native to Southern China. The bats are the animals that carry this virus permanently, chronically, endemically.

MARTIN: Which means that the entire SARS outbreak probably traced a path from a bat, to a palm civet, to someone eating in a restaurant, and then to the rest of the world. Scientists call diseases with animal origins zoonotic. It's a category that also includes Ebola, influenza, and HIV. In his book, David Quammen argues that these chains of infection are becoming more common for two reasons.

QUAMMEN: Disruption and connectivity. The disruption happens when we go into these wild habitats, we shake the trees and things fall out, including viruses. We kill and eat the animals and expose ourselves to their viruses. And then connectivity, we move ourselves and we move animal products, wild animals, domestic livestock around the world ever more quickly, ever more abundantly. So, the connectivity is there for these things to spread broadly through the human population once they have spilled over into just a few people.

MARTIN: Are scientists and medical researchers finding more cases because they're looking for them?

QUAMMEN: That's certainly a part of it, yeah. We are doing things that increase the likelihood of spillover, but we are also watching more carefully, we're searching more carefully. So, that's one factor - certainly not the only factor - that creates this drumbeat of concern.

MARTIN: How does this affect how you look at the world? Is there a paranoid bent to you, David?

QUAMMEN: I don't think there's a paranoid bent. I think the more I've looked into it, the more my irrational fears have been replaced by rational concerns. In some ways, it's cold comfort but I've realized that these viruses are very serious, yes, and they're not preternatural. Ebola virus - scary virus - but it's not preternatural. And when people have the ability to put on latex gloves and masks when they deal with the virus then you can stop it.

MARTIN: What will the next big one look like, based on what you have examined in all of your research? What can you predict at this point?

QUAMMEN: Well, I could only answer that question based on the experts of whom I've asked the same question. There will be a next big one. It will almost certainly be a zoonotic disease. It will be something that spills out of a wild animal. It will almost certainly be a virus. Now, that still leaves a level of uncertainty. Will it be an influenza? Will it be a SARS-like corona virus? That we don't know.

MARTIN: What do we do with that information?

(LAUGHTER)

MARTIN: As people who are not in the scientific world, you know, you hear that and you think, well, jeez. I mean, how - you just keep living your life, I suppose.

QUAMMEN: You do. You don't despair. You don't panic. You don't lay awake at night. You inform yourself the more people know about this subject, the more they understand it, the better and more sagacious will be their individual adjustments. There are things we can do. You know, don't eat monkey meat found dead in the forest.

MARTIN: OK. For starters.

QUAMMEN: Don't get on an airplane if you're feeling sick with some sort of a respiratory ailment. Get a flu shot. But at a deeper level, be attuned to the fact that this is a very serious problem, but it's a problem that researchers all over the world are working on and devising responses for. Know about it and cope with it, but don't worry about it.

MARTIN: That's science journalist David Quammen. His new book is called "Spillover: Animal Infections and the Next Human Pandemic.

(SOUNDBITE OF MUSIC)

MARTIN: You're listening to WEEKEND EDITION from NPR News.

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