Researchers believe that the coronavirus that causes severe acute respiratory syndrome (SARS) in humans probably originated in an animal in southern China.

Possible hosts for the SARS virus include bears, monkeys, and the endangered pangolin (above)

MICHAEL PITTS/NATUREPL

That was the conclusion drawn by a group of experts meeting at the New York Academy of Sciences to discuss the origins of SARS and the state of development of a vaccine or antiviral drug to help quell the virus.

SARS has killed 642 people and infected 7860 across the world. No one understands why SARS makes some people sicker than others and why some people seem to be more likely to spread it to others.

It could be linked to stress or to infection with something else as well as SARS, such as influenza or hepatitis, researchers said. Co-infection with other infections is known to worsen coronavirus infection in farm animals. The disease's long incubation period—estimated to be two to 10 days, or even 14 days—makes the virus perfect for travel. It gives infected individuals enough time to go elsewhere before they get sick.

Experts who examined the genetic map of the SARS virus say …