Spillover: Animal Infections and the Next Human Pandemic

NPR has an interview with the author of this book. An excerpt:

How did we go from a virus that’s found largely in animals to a virus that can be deadly for humans — and spread across four countries?

Human behavior is causing this problem. More and more, we’re going into wild, diverse ecosystems around the world, especially tropical forests.

Some scientists believe that each individual species of animal, plant, bacterium and fungus in these places carries at least one unique virus, maybe even 10 of them.

We, humans, go into those wild ecosystems. We cut down trees. We build mines, roads and villages. We kill the animals and eat them. Or we capture them and transport them around the world.

In doing that, we expose ourselves to all these viruses living around the world. That gives the viruses the opportunity to spill over into humans. Then in some cases, once the virus makes that first spillover, it discovers that it might be highly transmissible in humans. Then you might have an epidemic or a pandemic…

The experts I talk to say the next big one will almost certainly be caused by a zoonotic virus, coming out of animals. And it’s likely to be one that is transmissible through the respiratory route — that is, through a sneeze or cough.

Ebola is not an easily transmissible virus. It requires direct contact with bodily fluids. It doesn’t travel on the respiratory route.

Viruses such as the and SARS are much more of a concern to scientists that study these things than Ebola because they are already transmissible through the respiratory route. They are also highly adaptable, and they mutate quickly.

In terms of the next big one, SARS and MERS stand higher on the watch list than Ebola.