Ebola, Lassa, Marburg and HIV are frightening examples of these deadly organisms. The death tolls where they strike are sobering. Even the flu virus can be a killer. We’ve known about it for many decades now, but flu experts are still involved in a full-time race to keep up with the virus as it mutates.
埃博拉、拉沙、马尔堡病毒以及艾滋病病毒，都是这些致命微生物的可怕的例子在它们肆虐的地区，死亡人数之多令人警醒。即便是流感病毒都能够致人死命。虽然我们早在几十年前就发现它，可是流感专家们仍在全力与时间赛跑，以便跟上流感病毒变异的速度。
