Zhengli Shi of the Chinese Academy of Sciences in Beijing and colleagues find that almost 70 percent of the bat species sampled in the region showed evidence of infection with SARS-like viruses.

This would support the idea that bats are the natural host of the virus.

Severe acute respiratory syndrome or SARS first emerged in China in 2002 and in 2003 spread around the world via jet, killing more than 700 people and infecting about 8,000. Strict quarantines and other measures stopped its spread.

It is caused by a new virus called SARS coronavirus. Coronaviruses are common in people and animals and usually cause nothing more serious than a cold.

Researchers hypothesize that an infected bat could have been kept in a cage next to a palm civet, an animal infected with coronavirus. The civet might then have become infected and passing the virus to humans.