The virus has mutated dramatically in the last two years to form two distinct families, if you will, of the H5N1 viral tree with branches in them, and with different attributes that are worrying.
在过去的两年里，病毒已经明显的突变成 两个截然不同的家族， 正如你想的那样 H5N1就是其中的分支之一。 并且H5N1有着让人心神不安的特点。