Government officials have declared a public health emergency in connection with the swine flu outbreak that has killed dozens in Mexico and sickened 20 in the U.S., said the nation's director of Homeland Security said Sunday. Janet Napolitano also said border patrol agents have been directed to begin passive surveillance of travelers from Mexico, with instructions to isolate anyone who appears actively ill with suspected influenza. The number of cases confirmed in the United States by the federal Centers for Disease Control and Prevention is now 20.
