A virus turns much of the human population into vampires.

VOA: special.2010.01.20

That's important, too, because you need to be able to tell if the virus is present in the human population.

这一点也非常重要,因为你要能够分辨出,人群中是否有人感染了天花病毒

耶鲁公开课 - 生物医学工程探索课程节选

"It so happens that in some parts of Bolivia, this over-population of yacares is detrimental to human life So,there is a real claim there to sustainably manage the yacare population, which means killing them.

VOA: standard.2010.01.31