[Newticus]

virus's are different then bacteria, because in essence they are not living things, they are particles. These particles have coats and casings to proctect them from drying out or falling apart while waiting for an appropriate host. The amount of time they can survive outside of a host varies, due to coat and casing structure. Some can last a rather long time.
There are disinfectants that do destroy the parvo virus, we used to use them at the pet store I worked at, we have had to change cleaners a few times because after a while the one cleanser doesn't work as well. Parvo is an extreamly aggressive adaptable virus which makes it very hard to combat. Even in the cleanest places it can still survive at times and cause heartbreak.

Melanie