U.S. health authorities say a previously unknown virus might be the cause of the Asian pneumonia that has killed 17 people worldwide as of Monday. It is the third virus to become a suspect in the case.
Officials at the U.S. government's Centers for Disease Control, the CDC, said they have detected a new virus in nine patients infected with the respiratory disease called SARS.
Laboratories in Hong Kong, Germany, and Canada had detected two other viruses in other patients earlier.
But CDC director Julie Gerberding said her agency's findings suggest that the third virus is involved because, unlike the previous two, it was detected in several different body tissues.
"This virus could, in fact, could be if not the entire cause of SARS, at least contributing to SARS," Ms. Gerberding said.
The virus in question is a coronavirus, two strains of which cause one-third of common colds.
Coronaviruses are not usually deadly, but the CDC said its examination of the genetic structure of this one indicates it is a new type.