The global spread of the mysterious flu-like illness that has killed 10 people in the past three weeks appears to have started with a guest in a tourist hotel here.
Hong Kong health officials said Thursday that other guests who caught the disease then carried it to a Hong Kong hospital, Vietnam, Singapore and Canada. Three of the seven people who stayed on the ninth floor of the Metropole Hotel died from severe acute respiratory syndrome, or SARS.
There are now 306 people sick with the disease, according to the World Health Organization. About half those are in Hong Kong, the vast majority in Asia. There are 13 suspected cases in the United States.
The cause of the illness remains unknown, but experts believe the most likely explanation is a new virus. There is no known treatment.
Hong Kong health officials have traced the outbreak to a professor from China's Guangdong province who stayed at the Metropole Hotel on Feb. 21-22. He died March 4.
His case bolsters the belief that the outbreak stems from one that began last November in the southern part of Guangdong, where 300 people were sickened and five died.
The Metropole, a bland-looking, rectangular building, is a three- or four-star hotel located in a residential district of Hong Kong's Kowloon peninsula, an area where many tourists stay. It is a short bus ride away from the main tourist area of Tsim Sha Tsui.
During the two days the infected Chinese professor stayed on the ninth floor, three women from Singapore were guests on the same floor. After they returned home, they became ill. Singapore's Health Ministry said all 34 Singapore SARS patients had been in contact with the three women.
An American businessman from Shanghai also stayed on the ninth floor of the Metropole before flying on to Vietnam and falling ill, officials said.
"His name was Johnny Chen," said Hoang Thuy Long, director of Vietnam's National Institute of Hygiene and Epidemics. "When Mr. Johnny Chen came to Vietnam, he was actually in an incubation period."
Two days after his arrival, he was hospitalized at the Hanoi French Hospital, but asked to be moved to a hospital in Hong Kong where he died.
A third Metropole guest during that time was a 78-year-old woman from Toronto. She returned home where she infected her grown son. Both died.
In addition, a Hong Kong man visited a friend on the ninth floor while the professor was there, health authorities said.
That man has been identified as the Hong Kong "index patient" who spread the disease to the Prince of Wales Hospital, where dozens of workers have been sickened, said Health Department spokeswoman Sally Kong.
It remains unclear how the disease would have spread in the hotel. One expert has speculated it could have spread from the air-conditioning.
"Perhaps they all stood outside the elevator at the same time and someone sneezed or coughed," said Dr. Margaret Chan, the director of the Hong Kong Health Department.
None of the 200 to 300 workers at the Metropole have become ill, Chan said.
Since the outbreak, hotel spokeswoman Anita Kwan said, guests had been given a letter explaining what had happened. She said none had been scared away.
But a group of tourists from Shanghai emerged wearing surgical masks early Thursday and told reporters they were seeking different accommodation.
"The Health Department has already indicated that the germ doesn't exist here anymore," Kwan said Wednesday night. But she added that the ninth floor won't be reopened until it has been thoroughly checked.
Dr. David Heymann, WHO's communicable diseases chief, said Thursday the cases at the hotel do not diminish the view that the illness is spread only by close contact because such a scenario has not been ruled out.
"There is no evidence of casual contact," he said. "Speculation can go from it being a pigeon sitting on a window sill, flapping its wings outside four rooms, to anything under the sun."
If the illness was spread as easily as passing somebody in a corridor, or through the air conditioning system, cases would likely have shown up elsewhere in the hotel, experts said.
While new cases continue to turn up daily, health officials are encouraged to see that reports of recovery are also on the rise.
"In Vietnam there are 20 patients now out of 56 who are much better, and some are ready for discharge from the hospital," Heymann said.
A Singapore doctor and his wife and mother-in-law who were on their way home when they were quarantined in Frankfurt, Germany, are also recovering, doctors there said.
It is unclear whether medications are helping them recover or whether they would have got better anyway.