It was a balmy Sunday evening in early 1999, and Dr. Kaw Bing Chua hadn’t had lunch or dinner.

There wasn’t time to eat. Chua was chasing a killer. And he thought maybe he had finally tracked it down.

He slid the slide under the microscope lens, turned on the scope’s light and looked inside. “A chill went down my spine,” Chua says. “The slide lit up bright green, like bright green lanterns.”

Right there, in Chua’s hands, was a virus the world had never seen before. And as he soon learned, it’s also one of the most dangerous ones.

Now Chua had enough of the virus to kill everyone in the lab. Maybe worse.

The new virus — eventually called Nipah — is on the World Health Organization’s list of viruses most likely to cause a global pandemic. It’s the virus that inspired the 2011 movie Contagion. And just this past January, governments and philanthropists pledged hundreds of millions of dollars to develop a Nipah vaccine because it poses such a big threat.