BEIJING -- Tracking the origins of China's latest confirmed SARS case, international medical investigators scoured a southern Chinese apartment block in an effort to determine if anything there played a role in the infection.
The World Health Organization said today it had no immediate information on a report in one Hong Kong newspaper saying a third suspected case of severe acute respiratory syndrome was being treated in the southern province of Guangdong.
At the same time, experts worked today to process laboratory samples taken from a restaurant that employed a woman who has become another suspected case. They said they found no immediate conclusions about whether her job was linked to her illness.
"It's swabs from parts of the restaurant that we're looking at," WHO spokesman Roy Wadia said in a telephone interview from Guangzhou, Guangdong's capital. The samples were taken Saturday from the establishment, which didn't specialize in wild game but served some wildlife, including civet cats.
Thousands of civets were slaughtered in Guangdong during the past week on suspicions they could have transmitted SARS to human beings. Although the virus has been found in the weasel-like mammals, there has been no definitive proof of their status as a human vector.
"Basically, most of the civet cats in Guangdong have been slaughtered," said an official at the Guangzhou Anti-SARS Office.
The province -- where SARS is believed to have first appeared and where this year's first confirmed and second suspected cases are both located -- is in the midst of a massive cleanup effort.
Authorities are now turning their attention to pests like roaches and rats.
The Guangzhou-based newspaper Yangcheng Evening News said on its Web site Sunday that more than 10 tons of grain laced with poison had been deployed in a three-day campaign to eliminate rats.
"Exercise caution in dealing with rat carcasses," it warned, quoting authorities.
The suspected case of SARS, a 20-year-old waitress, has been isolated for treatment. The confirmed case, a 32-year-old television producer named Luo, recovered from the illness and left the hospital last week. He told authorities he came into contact with no wild animals, and the source of his infection remains a mystery.
Today, his apartment block in Guangzhou was the site of a flurry of WHO activity as investigators scoured it looking for possible modes of infection.
"We're talking to management, getting a feel for how the buildings are laid out, the ventilation, things like that," Wadia said.
He said WHO was also working with the Guangdong Center for Disease Control to examine all data collected so far.
Today, a Hong Kong newspaper, the Oriental Daily, said a third suspected SARS patient was being treated in Guangzhou's No. 8 People's Hospital, where the other two were admitted. It didn't cite its source, and WHO said it had no information.
At the Guangdong SARS Prevention Office, a woman who answered the phone today said she had no new reports of suspected SARS cases. She gave only her surname, Zhou. At the hospital, no officials were available to discuss the matter, an operator said.
The five-member WHO team flew to Guangdong on Friday to join Chinese experts in the search for the source of the disease.
The first outbreak of SARS began last winter. It killed 774 people worldwide and sickened more than 8,000.