Although coughing and sneezing remain the chief means of spreading the infection, government scientists in Hong Kong have found that the virus can stay alive for at least four days in diarrhea.
The research adds weight to the theory that leaky sewage pipes were the source of infection in a particularly severe outbreak at a Hong Kong apartment complex, where more than 300 people became ill.
The report was among several new findings Sunday. One study found that the SARS virus can live on chilled surfaces like those in a refrigerator for as long as four days. Another found common disinfectants can kill the virus.
Globally, SARS, or severe acute respiratory syndrome, has killed at least 449 people and sickened more than 6,300.
Thirteen new SARS deaths were reported Sunday in east Asia, seven in mainland China, five in Hong Kong and one in Singapore. The number of new cases in Hong Kong -- eight -- continued to decline.
Two doctors from the World Health Organization arrived in Taiwan on Sunday to help the island cope with its worsening SARS outbreak, after China's government put aside politics and agreed to the visit.
The number of probable SARS cases in Taiwan has tripled in the past 10 days to 116, and there have been eight fatalities including five announced Friday. Taipei's mayor warned that violators of home quarantine orders would be punished.
Dr. Klaus Stohr, the WHO's chief SARS scientist, said discovery that the virus can survive in feces at room temperature for as long as four days was ''the most exciting, or perhaps disturbing, finding.''
He said diarrhea provides a more favorable environment for the virus as the stool in that condition is less acidic.
Although only about 10 percent of people stricken with severe acute respiratory syndrome get diarrhea, the rate among patients infected in the Amoy Gardens apartment complex was 60 percent.
''That finding is the most disturbing one because it would suggest that fecal-oral transmission could take place,'' said Stohr, who was not directly involved in the research but coordinates the work of labs around the world investigating the SARS virus.
In another experiment, Stohr said, Hong Kong University scientists confirmed that common disinfectants can kill the virus in five minutes.
''The good news from these findings is that the virus can be relatively easily killed with common disinfectants,'' he said. The Hong Kong scientists found that formaldehyde, ethanol and acetone, three common disinfectants, kill the virus.
Disinfecting toilets in hospitals and homes where people have had contact with SARS would likely solve the problem, he said.
Stohr said that in an ongoing study, Japanese researchers had found that the SARS virus had so far stayed alive for four days in cells on plastic surfaces at a temperature of 40 degrees.
''This is fridge temperature, so if someone touches something with a SARS contaminated hand, it would stay for four days on something in the fridge,'' Stohr said.
The virus was also tested at minus-112 degrees for four days and it was unaffected. But this was no surprise, Stohr said, because many viruses survive easily in cold temperatures.
It was already clear that the SARS virus can survive winter. The outbreak began in November in China and survived the winter there to spread farther afield in the spring.