This requires viruses to infect living organisms.

这需要病毒感染生物体。

A disease is Contagious if it is caused by some type of infecting organism that is spread human to human. Not all diseases involve an organism and not all organism involved diseases are transmitted person to person.

5. 如果某种疾病是由某种在人与人之间传播的感染性有机体引起的，则该疾病具有传染性。并非所有疾病都涉及生物体，也并非所有涉及生物体的疾病都会在人与人之间传播。