Apparently pets can spread the disease, as well. And the truth is that no (or almost no) adults are that "clean and pristine" anyways, we're grimy creatures despite how much we may try to dissociate ourselves from the rest of the animal kingdom.

And that's without getting into how horrible the basic hygiene of many people is. All humans piss, shit, eat, sometimes get food on their hands or intentionally and purposefully eat with them, most people dig their nose, or rub their face, or touch their eyes, or scratch their ass, etc. Anyone who says they never do any of the above is a liar; maybe they're more hygienic about it as is sensible and wash their hands after, but it's a fact of life.