Local outbreaks of new diseases have occurred throughout history, but in this age of global jet travel and international commerce, a deadly virus can spread rapidly worldwide.
That's what happens in "Contagion," a gripping new medical thriller directed by Steven Soderbergh.
It starts with a nagging cough, which spreads through something that seems harmless, like a handshake or flipping a light switch.
The unknown and deadly virus in "Contagion" crosses the Pacific with an American businesswoman returning home from Asia. Within days, she is dead and dozens of people she infected are dying, triggering a response from the U.S. government's Centers for Disease Control.
Screenwriter Scott Z. Burns has plenty of experience with fictional thrillers like "The Bourne Ultimatum," but says the "Contagion" script is about a very real threat.
"All of the scientists that we spoke to about it said it's not a matter of if, it's a matter of when," Burns says. "We had started writing the movie and about three or four months into the research is when H1N1 (swine flu) happened. So that became a really interesting tracer bullet through the system for us to follow some of the issues."
The cast includes Gwyneth Paltrow as Beth Emhoff, the businesswoman whose death sounds the alarm. Matt Damon, who plays her widowed husband, says the participation of real medical professionals gave the film a ring of authenticity, such as the scene where his character is told of his wife's death.
"We had a guy there who really had done this a lot - this doctor who delivered this news - and we asked for certain trends, like what happens," Damon says. "He said sometimes people fall apart, but he said, 'There is this other reaction that we get a lot…it's just too much' and they expect you to not even get it."
In the film, when Damon's character is told of his wife's death, he says, "Okay, so can I go talk to her?"
Director Soderbergh adds to the sense of realism by avoiding the cinema clichés which are usually part of the disaster genre. While making the film did not turn him into a 'germophobe,' Soderbergh admits that he is more conscious of the danger and thinks audiences will be as well.
"It was fun during the previews to watch the lights come up and 400 people realize that they are next to a bunch of strangers and that they've touched everything," he says.
"Contagion" was filmed at locations in China and the United States with an international cast which includes Laurence Fishburne as the CDC chief, Kate Winslet as an epidemiologist and Marion Cotilliard as her World Health Organization counterpart tracing the origins of the virus. Jude Law plays an Internet blogger whose half-baked conspiracy theories threaten to spread panic.