A highly contagious and deadly pneumonia-like illness is fast becoming a worldwide health threat, the World Health Organization warned Saturday. The illness also claimed another victim, a nurse who died in Vietnam.
In a rare "emergency travel advisory," the health agency said it has received more than 150 reports of what it called "Severe Acute Respiratory Syndrome" in the past week, mostly in southeast Asia.
At least four people have died this month -- an American businessman, a Vietnamese nurse who treated him and two people who arrived in Canada recently from Hong Kong. An outbreak of pneumonia with similar symptoms killed five people and sickened 300 in southern China between November and mid-February.
"Health officials around the world are taking this situation very seriously," U.S. Health and Human Services Secretary Tommy Thompson said Saturday.
The department was "applying a full-court press to learn more about this outbreak and how it might impact on the United States," Thompson said.
Symptoms may include coughing, high fever and shortness of breath, with headache, muscular stiffness, loss of appetite, confusion, rash and diarrhea also possible.
Singapore reported four new infections Sunday, bringing its total to 20. Taiwan reported three. A man from the Philippines who visited Vietnam earlier this month also has been diagnosed with atypical pneumonia.
While no formal travel restrictions are in place, U.S. health officials said travelers should consider postponing trips to countries at risk. Health officials are preparing an alert for people returning from countries where the illness has been reported.
The growing list of countries reporting cases of the illness include China, Hong Kong, Indonesia, Philippines, Singapore, Thailand and Vietnam. Most cases involve medical workers.
Doctors do not know what causes the illness -- even whether it is a bacteria or virus.
WHO spokesman Dick Thompson said in Geneva, "Until we can get a grip on it, I don't see how it will slow down. People are not responding to antibiotics or antivirals. It's a highly contagious disease and it's moving around by jet. It's bad."
No cases have been identified in the United States, health officials said. But a Singaporean doctor believed to be infected was taken off a New York-to-Singapore flight in Germany on Saturday and quarantined.
The 32-year-old man showed symptoms of pneumonia and was being treated with antibiotics, Dr. Hanns-Reinhardt Brodt said at a news conference. X-rays and lab tests showed the man's condition had "worsened slightly," Brodt said.
The man's mother-in-law had a high fever but no other symptoms, while his pregnant wife showed no signs of infection, Brodt said.
In New York, health authorities put hospitals on alert.
A man traveling from Atlanta to Canada is "reported to have developed some respiratory symptoms," said Dr. Julie Gerberding, director of the federal Centers for Disease Control and Prevention in Atlanta.
The illness is believed to spread "person to person" and have an incubation period of two to seven days, Gerberding said. "There is no evidence to suggest that this can be spread through brief contact or assemblages of large people," Gerberding said.
When asked whether the illness could be caused by bioterrorism, Gerberding said, "We have an open mind and will be keeping an open mind as we go forward."
One of the most severe outbreaks has been in Hanoi. A CDC team flew to the Vietnamese capital Saturday and gathered samples from people who may be infected. The samples were immediately flown to Atlanta for testing.
"SARS is now a worldwide health threat," Dr. Gro Harlem Brundtland, the WHO's director general, said in a statement issued in Geneva. "The world needs to work together to find its cause, cure the sick, and stop its spread."
The Singapore doctor began suffering symptoms while in New York, said Dr. Angela Wirtz, a health official in the German state of Hessen, where he is being treated.
The man recently attended a New York conference, but it was not immediately known exactly when he was in the city.
The remaining 220 passengers on the flight were temporarily quarantined Saturday. By the end of the day, more than half had been released after authorities determined their risk of infection was "extremely low."
In Atlanta, the CDC emergency operations center has been activated.
In Canada, Toronto Public Health officials said a woman died on March 5 and her adult son died on March 13 after arriving recently from Hong Kong. Four of their relatives were hospitalized.