The disease triggers flulike symptoms high fever, coughing, shortness of breath but because it hasn't been responding to either antibiotics or antivirals, doctors can't immediately tell what causes it. For now they are calling it SARS for Severe Acute Respiratory syndrome. Scientists speculate that it may be a bacterium or a virus that has mutated into a new, more virulent form.
So far, almost all the cases have been in Asia. One of the worst outbreaks, in Hanoi, apparently started after an American traveling through Vietnam fell ill and infected more than two dozen hospital workers; he died last Thursday in Hong Kong. No travel bans have been issued, but health officials are discouraging nonessential flights to Asia and urging travelers who suspect they have the illness to see a doctor and not fly again until they recover.