Living organisms are constantly in contact with pathogens which, under the proper conditions, are able to parasitically proliferate to create pathological conditions.

活的生物体是在与病原体接触不断，在适当的条件下，能够寄生繁殖创造病理状态。

He would court opprobrium if he were to argue that, as a class of human beings, they lack morals or self-control, or to claim that they exist parasitically on the hard work of others.

如果他提出，黑人作为人类的一种，是缺乏道德和自控的，或者说他们寄生于他人的辛劳工作之上，他将遭到责骂。