And last year they saw how the rare hantavirus,once unknown in the U.S.,emerged from mice to kill 30 people in as many as 20 states.

• 而去年，他们见识到罕见的病毒性流感，美国人过去完全陌生的病毒，如何从老鼠身上传出，在广达20个州境内夺走了30条人命。