Diseases that jump from animal to human populations are called zoonotic pathogens and they have been the source of some of the most deadly outbreaks in human history. The black plague was a zoonotic pathogen and recent outbreaks in SARS, Ebola, West Nile, Lyme, MERS, and other diseases have done considerable damage to the human race.
The common link between them? They have roots stemming in human made environmental changes.
The problem does not just stem from people hunting, trapping, and killing wildlife for consumption. The wet markets of China are the end result of practices that upset the biodiversity of wildlife's natural habitats. A healthy and biodiverse ecosystem has safeguards that would help restrain pathogens before they can spread wide. But when humans intrude on natural spaces they can upset that balance.
For example, many zoonotic pathogens live in prey animals, which reproduce quickly and can be carriers of disease without suffering the effects. The predator animals that feed on them are usualy the first ones brought to near-extinction when humans encroach on thier habitats.
“We are messing with natural systems in certain ways that can make them much more dangerous than they would otherwise be,” says Richard Ostfeld, a disease ecologist at the Cary Institute of Ecosystem Studies. “And biodiversity loss is one of those. Climate change is another.”
The biggest threat to the natural world is deforestation. It remains an incredibly profitable practice, but the profit for a few corporations is offset by the cost of health care treatment to the community from all the diseases that florish in the absence of a healthy ecological system.
We're seeing the end result of systemic damage to our world and the best way to prevent another catastrophic pandemic is to change the way we treat the natural world. Lee Hannah, senior scientist at Conservation International, suggested four things we can do to stop another outbreak like the one we're currently experiencing: stockpile masks and respirators; have testing infrastructure ready; and ban the global wildlife trade, and take care of nature.
“We need to tell people right now that there is a series of things we need to do once we’re out of this mess to make sure it never happens again,” Hannah says.