Recent scIscientific breakthroughs have been demonstrating the viral nature of our own DNA. Carl Zimmer in his NYTimes article HUNTING FOSSIL VIRUS IN HUMAN DNA describes the fascinating contribution of borna virus DNA to that of our own genome. Apparently it entered the primate line over 40 million years ago and persists in us.
It is estimated that over 8% of our DNA is of viral and possibly retroviral [like HIV] origins. It is presumed that the protein syncytin which allows the mammalian placenta to function is of viral origin.
It reminds me of the story of mitochondria in animal cells and chloroplasts in plant cells from Biology 101. Each carries its own characteristic DNA which differs from the DNA found in the nucleus of the same cell.
Presumably each were free-living cyanobacteria which merged with eukaryotic cells [cells with nuclei] a billion or so years ago. The symbiosis has allowed all life as we know it to develop and flourish on this planet.
So here we are–in a constant state of panic over which "bugs" we are ingesting or carrying around on our skins or in our lungs.
And clearly I am not against hygienic practices. Just want us to be aware that, in truth, we are the product of millions of years of co-evolution with the simplest of living things.