Sept. 11, 2013
There’s no such thing as living alone. Never mind if you’re the only person in your house and have no dog, no cat, not even fish. You’ve still got at least several billion roommates—and so do we all. Some of them are harmless, some are actually helpful and some could, in the right concentration and the wrong circumstance, kill you. They are, of course, bacteria, fungi and viruses, and like it or not, they’re on you, around you and deeply within you.
The fact that bacterial life is everywhere is not surprising. It’s something you learned practically from babyhood, every time your mom told you not to drink out of someone else’s glass during flu season. But when mothers say everywhere, even they don’t know the full meaning of that word.
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http://science.time.com/2013/09/11/your-tiny-roommates-meet-the-microbes-living-in-your-home/?hpt=hp_t3