Assessing Bird Flu

An outbreak of highly contageous bird flu that began in Southeast Asia three years ago, has now spread to Europe, the Middle East and West Africa. More than 200 million domestic birds have been killed to halt the advance of the virus, called H5N1. Ninety-eight people, who probably contracted the disease through contact with domestic fowl, have died. Scientists believe the virus could evolve and acquire characteristics that would make it easily transmissible among human beings, causing a global influenza epidemic. But they cannot predict when, or if, that will occur.