【英语时差8,16】流感--禽流感的爆发（在线收听）

There are some antiviral drugs that doctors may use to treat influenza. Each year, medical researchers work to develop vaccines to prevent the flu from infecting people. No one knows yet exactly how much protection the vaccine provided people this flu season.As of last week, the W-H-O reported that influenza remained widespread in many countries in central and eastern Europe. Humans are not alone. Chickens and some other animals also get the flu. Avian influenza virus has jumped to some people. Researchers are concerned about what could happen if the virus mixes genetic material with human flu virus. The new virus might then spread from person to person. Scientists are especially concerned about Asia, where many human influenza viruses first appear. In the current outbreak, the W-H-O says Vietnam and South Korea have the first epidemics ever documented in those countries. The World Health Organization says influenza is thought to result in two-hundred-fifty-thousand to five-hundred-thousand deaths a year. Lost productivity adds up to great economic costs. So medical and agricultural officials say stopping the spread of influenza is one of their most important jobs year after year.