A mysterious flu-like disease that has spread among health care workers has killed nine people in recent weeks, seven in Asia, and two in Canada after they had visited Hong Kong. Thus far authorities have been unable to identify the disease and are calling it Severe Acute Respiratory Syndrome (SARS). The World Health Organization issued a worldwide travel advisory to offer guidance to travelers and airline personnel, while the U.S. Centers for Disease Control advised deferring nonessential travel to the countries where the disease has spread, including China, Hong Kong, Indonesia, the Philippines, Singapore, Thailand and Vietnam. The risk to travelers is minimal, but all should be aware of the symptoms: high fever, one or more respiratory symptoms including cough, shortness of breath or difficulty breathing. Anyone who has been in one of these countries and experiences such symptoms should seek medical help immediately. The disease appears to be spread through close contact with an infected person, including direct contact with respiratory secretions or body fluids.