Do you ever wonder what happened to all the plagues that used to crop up throughout history? Well, Bill Gates does and he claims that another one could be just around the corner.

We’re long overdue for a pandemic if you believe in historical patterns, and Gates says it’s time we all prepared.

Gates spoke on Friday at a discussion about epidemics at the Massachusetts Medical Society and revealed that a catastrophic disease pandemic is likely to happen within the next ten years.

To get a better understanding of how a disease pandemic can spread so quickly across the entire Earth, watch the video below.

You’ll see a simulation of a global flu outbreak, complete with a map of how it spreads along with a death toll counter over the course of six months:

He says we need to treat and prepare for the threat in the same way we do with war.

While Gates maintained that he is actually an optimist, reminding people how we’ve managed to eradicate diseases like polio and are much better and preventing malaria, he said, “There’s one area though where the world isn’t making much progress and that’s pandemic preparedness.”

While new diseases do come into being all the time, especially as the world evolves and populations increase, become denser, or encroach on previously wild territory, engineered diseases are also of great concern.

Biological warfare has been a hot topic in recent years, and it’s become quite easy for individuals or independent groups to create dangerous diseases in a lab, capable of wiping out millions of people.