Who does not love the notion that we exist primarily as an environment for bacteria and viruses to live? I know I do and I am.
As we are aliens on planet bacteria it is hardly surprising that our hosts live all over us in return for letting us live here. In fact we probably would not survive here without their help.
It is not known just how many billions of them live on and in our bodies. It is popularly thought that the bacteria outnumber human cells in the body by 10 to 1 but that figure is disputed and it may be that the numbers of bacteria and human cells are about equal. The numbers reduce briefly after a bowel movements but increase with just about everything we touch.
Not to mention the animals that live on us.