From CNN:
PUZZLED BY the rapid but seemingly erratic spread of the new disease, a WHO team is visiting hospitals and talking with experts in the southern Chinese province of Guangdong, where the epidemic of severe acute respiratory syndrome began.
The four-member team is most interested in ?the phenomenon of ?super spreaders? - people who seem to spread their disease to a lot of other people,? said the WHO team leader, Dr. Robert Breiman.
Figuring out why they are so infectious ?may lead to public health approaches that will be very effective for control,? he said as new deaths were reported Saturday by Hong Kong and Malaysia.
Worldwide, SARS has killed at least 89 people and sickened 2,300 in more than a dozen countries. Symptoms include high fever, aches, dry cough and shortness of breath. No cure has been found.

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Aside from health care workers who caught SARS from patients, those infected have little in common, Breiman said.
Guangdong accounts for 40 of the 46 deaths reported in China. The first case was recorded in November and since then more than 1,100 people in the province have been sickened.
On Saturday, Vice Premier Wu Yi was quoted by state media as calling for a national disease warning system, with a focus on fighting SARS and ?emphasis placed on a public health information system.?
Wu?s comments, carried by newspapers and the Xinhua News Agency, were the highest-level response yet to demands that the secretive communist government change its handling of such outbreaks. The report followed an extraordinary apology Friday by the country?s top disease-prevention official amid international criticism that China released information too slowly.

TRACKING THE CAUSE
Malaysia reported its first likely death from SARS, which has now killed more than 80 people and infected around 2,400 worldwide.
In Thailand, which has suffered two deaths, Health Minister Sudarat Keyuraphan said he might call on military medics to help screen airline passengers for SARS.
Singapore, with six deaths, said its number of new infections was dropping. Authorities said people should resume their normal routines and that schools would reopen in the coming week.
[Sign up for our health e-newsletter] Experts have linked SARS to a new form of coronavirus, other types of which usually are found in animals. But Chinese specialists say they found a rare airborne form of chlamydia ? a virus usually transmitted through sexual contact ? in many who died.
The finding has raised yet another question: Is the sickness caused by one virus or bacterium and made more lethal by another?
?If you have one pathogen and you get hit with, say, coronavirus, (do) you get a particularly bad disease?? Breiman said. ?Or are you more likely to transmit? Do you become ... a ?super spreader???
The WHO team, which includes specialists who work in the United States, Germany, Wales and Bangladesh, planned to stay in Guangdong through Tuesday.
Guangdong is a key engine of growth for China. Foshan, for example, makes 80 percent of the world?s microwave ovens.
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World health experts are trying to identify the cause of severe acute respiratory syndrome, or SARS, a new form of deadly pneumonia that is spreading rapidly through Southeast Asia and other parts of the world. For more information about the illness, click on a question above.
Most patients start out with a fever greater than 100.4 ° F (38° C) and often have accompanying chills, headache, malaise, body aches and mild respiratory symptoms. In the early stage, many patients have a decreased white blood cell count and may also have diarrhea. After 3 to 7 days, the patient may develop a dry, non-productive cough that increases in severity. As the disease progresses, chest x-rays may show significant congestion in the lungs. Eventually not enough oxygen can get to the blood and, in 10 to 20 percent of cases, patients will require mechanical ventilation. The severity of illness among patients is highly variable, ranging from mild symptoms to death. Only patients who have traveled within 10 days of the onset of symptoms to an area with suspected SARS cases, or have had contact with a person suspected of having SARS, are considered possible carriers of the disease.
SARS appears to spread through close contact, such as between family members or between patient and doctor. Experts believe it is transmitted through coughing, sneezing and other contact with nasal fluids. Researchers are also looking into the possibility that it is spread through the air, but this has not yet been confirmed. Once someone has been exposed to the illness, it takes three to seven days for symptoms to develop.
Researchers are not yet certain what pathogen is behind the illness. CDC scientists recently said the disease may be caused by a new form of the coronavirus, one of a few viruses that can cause the common cold. Other researchers have found signs of another germ family, the paramyxovirus, which causes measles, mumps and other diseases. SARS may be caused by one of those two viruses or it?s possible they are working together.
Patients suspected of having the illness are being quarantined in hospitals. Until health officials learn its cause, there is no definite course of treatment. Some doctors have reported that patients respond well to treatment with antiviral medications and steroids.
The fatality rate among persons with SARS is approximately 3 percent, according to the World Health Organization.
The CDC says travelers should consider postponing trips to countries at risk, including Hong Kong and China. In addition, the U.S. State Department has warned citizens not to travel to Vietnam because the country lacks medical facilities to deal with the outbreak there. The CDC has begun handing out notices to travelers returning from Hong Kong, China and Vietnam warning them to be on the lookout for symptoms of SARS. Americans living abroad are urged to avoid activities, such as visits to hospitals, that might bring them into contact with people who have SARS. Airline crew members are asked to be on the lookout for sick passengers and quickly isolate them from other passengers if possible.

Suspected cases of SARS have been reported in China, Hong Kong, Taiwan, Singapore, Thailand, Vietnam, Canada, United States, France, Germany, Switzerland, Italy, Britain and Ireland. So far China, Hong Kong, Vietnam, Singapore and Canada are the only countries with reported deaths from the illness.
In the United States, people who think they may have SARS and have recently traveled to Asia, or have been in contact with someone who has, should contact their doctor for a full evaluation. Health workers who suspect cases of SARS are asked to report them to their state health departments. The CDC requests that reports of suspected cases from state health departments, international airlines, cruise ships, or cargo carriers be directed to the SARS Investigative Team at the CDC Emergency Operations Center (770-488-7100). Outside the United States, health workers who suspect cases of SARS are requested to report them to their local public health authorities.

Chinese Health Minister Zhang Wenkang has stressed that the outbreak is under ?effective control,? and Guangzhou still plans to host its flagship trade fair this year. But analysts say that global high-tech supply routes are threatened by SARS-related manufacturing disruptions and travel bans.
Millions of Chinese are due to be on the move over the week-long May 1 Labor Day holidays. China, which counts on three ?Golden Week? holidays a year to help fuel consumer spending, appeared eager to keep public concern at a minimum.
?All of China?s tourist attractions are guaranteed to be safe and healthy,? said a headline in the People?s Daily.
The public is not so sure. At Beijing?s Babaoshan Cemetery for Revolutionary Martyrs, some mourners wore facemasks to visit the graves of ancestors on Saturday for the annual Ching Ming tomb-sweeping festival.
The Lo Wu border crossing between Hong Kong and Shenzhen, normally packed each year with people headed to mainland cemeteries, reported unusually light traffic.

HOSPITAL CRISIS
Hard-hit Hong Kong has seen its health care system thrown into crisis, as doctors and health care workers succumbing to infection can no longer cope with treating other life-threatening illnesses at some hospitals, newspapers reported on Saturday.
A top doctor at United Christian Hospital, where at least a dozen medical staff have been infected with SARS in the past few days, said the Hospital Authority overseeing the former British territory?s health care system was unable to handle the outbreak.
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?The entire Hospital Authority is in crisis,? the Ming Pao newspaper quoted an excerpt from the e-mail as saying.
?We cannot only look after SARS patients. Heart disease is equally fatal. Operations on patients with heart disease have stopped for a week now,? a United Christian doctor told the newspaper after a hospital briefing on SARS.
The hospital has admitted some 200 SARS patients in the past week, most from a Hong Kong apartment complex, Amoy Gardens, that was sealed off after more than 200 residents were suspected of coming down with the virus.
Although WHO says the disease is less infectious than influenza, and the death rate from SARS so far has been between three and four percent, experts say patients in areas without good medical facilities face a higher mortality risk.
The disease has squeezed air travel and cut hotel occupancy rates in some Asian hotspots, reached 19 countries or regions and has many governments bracing to meet the threat.
Vietnam, where the spread of the disease was thought to be in check, quarantined a doctor suspected of catching SARS from a patient, along with 43 others with whom he had contact.
Australia posted doctors and nurses at major airports on Saturday to monitor travelers for SARS, armed with the power to quarantine people with suspected symptoms.
In the United States, which has 115 suspected cases of SARS, President Bush issued an executive order allowing health officials to use forced quarantine of patients if needed.
Continental Airlines suspended Hong Kong to New York flights until the end of May, and the national airline in Mauritius halted flights to Singapore and Malaysia over SARS fears.

The Associated Press and Reuters contributed to this report.