If we fail to understand and take care of the natural world, it can come back to haunt us in ways we know little about. A critical example is a developing model of infectious disease that shows that most epidemics — AIDS, Ebola, West Nile, SARS, Lyme disease and hundreds more that have occurred over the last several decades — don’t just happen. They are a result of things people do to nature.

Disease, it turns out, is largely an environmental issue. 60% of emerging infectious diseases that affect humans are zoonotic — they originate in animals – and more than two-thirds of those originate in wildlife. Teams of veterinarians and conservation biologists are in the midst of a global effort with medical doctors and epidemiologists to understand the “ecology of disease.” It is part of a project called Predict, which is financed by the United States Agency for International Development. It isn’t only a public health issue, but an economic one. The World Bank has estimated that a severe influenza pandemic, for example, could cost the world economy $3 trillion.