A mystery disease spread new fears across Asia on Monday as Singapore quarantined hundreds of people, and Hong Kong and Vietnam reported more deaths amid closed schools and growing fear.
At the same time, scientists in Geneva and the United States said they believe the cause of the flu-like ailment that has stymied them for weeks could be one of the viruses that causes the common cold.
The U.S. Centers for Disease Control and Prevention said Monday that evidence is mounting the cause is a coronavirus, a bug that can cause colds.
CDC director Dr. Julie Gerberding in Atlanta said a form of the virus unlike any seen in humans before has been found in the lungs and other tissue of some victims.
Furthermore, patients seem to develop antibodies to the virus as they get sicker with the pneumonia, Gerberding said.
There is no known treatment, although the World Health Organization said last week it had developed a reasonable test for diagnosing the disease. CDC scientists are skeptical of its accuracy.
The illness, called severe acute respiratory syndrome, SARS, has produced 456 cases and 17 deaths since Feb. 1, WHO says. Those figures do not include cases and deaths from mainland China where the disease is believed to have begun in November.
Hong Kong accounts for more than half the reported cases around the world, with 260, and 10 deaths, two of those reported Monday. Vietnam also reported two new deaths Monday, just two days after the U.S. State Department advised citizens to avoid travel to the country because its hospitals are in crisis.
The WHO also reported another death in Canada, bringing that country's total to three. There have been no deaths in the United States.
In the meantime, Hong Kong government officials met to draw up health guidelines for everything from restaurants to bus systems in an attempt to slow the spread of the flu-like illness. And the territory's health secretary, Dr. Yeoh Eng-kiong, called it "a really very alarming disease," the likes of which Hong Kong has never seen.
On Sunday, the news that Hong Kong's health chief was hospitalized with the respiratory symptoms indicative of the disease merely added to the anxiety.
"I think it's spreading very quickly," said Lisa Fung, a masked 44-year-old worker at a domestic help recruitment agency. "Even William Ho has got it and he hasn't had to go treat the patients."
It was not known immediately if Ho was sick with SARS, which has symptoms of a fever of at least 100.4, combined with coughing, shortness of breath or difficulty breathing. But Hong Kong officials noted he had been going through hospitals to offer moral support to front-line medical workers and patients.
Health authorities suspect SARS is linked with an earlier atypical pneumonia outbreak in mainland China's Guangdong province that killed five people and sickened 305. A WHO team that arrived over the weekend in Beijing said Monday it was analyzing the Chinese cases in the scramble to unravel the disease.
For days, Hong Kong officials had said that SARS did not threaten the community at large, but Yeoh issued new warnings on Monday, urging people with flu-like symptoms to stay away from work and school.
"The situation now is very difficult," he said.
Government officials were planning guidelines for hospitals, schools, transport systems, public housing and restaurants. Four schools were closed temporarily, after seven students, a teacher and a bus driver were infected, although their cases were linked to sick relatives.
Singapore's efforts to contain the disease came as Health Minister Lim Hng Kiang announced he was invoking the Infectious Diseases Act for what could be the first time since the city-state gained independence in 1965.
Over the weekend, Singapore said it would empty one of its main hospitals and dedicate it to coping with the disease.
The health minister said authorities had ordered about 740 people who may have been exposed to victims of the illness to stay home for 10 days and have no contact with others. Any quarantined person caught outside his home could face a fine of up to $2,825.
In Hong Kong, many residents wore surgical masks around the city, hoping to avoid infection.
Officials offered some encouragement, saying that many of the sick seemed to improve with steroids and an anti-viral drug, ribavirin. Some of the sickest Hong Kong patients were receiving injections of antibodies obtained from victims who have recovered and their initial responses appeared good, Yeoh said.
WHO scientists said they still had not ruled out the possible cause of paramyxovirus, which causes measles, mumps and canine distemper.
"We now have two major (virus) groups and it's up to the laboratories to see where the virus is going to end up," said Dr. Klaus Stohr, a WHO virologist who is coordinating the work of WHO's network of 11 labs.