The only way to avoid catching Parvo is to be up to date on vaccines and to avoid infected materials and locations until after all immunization shots have been completed. This means avoiding locations where the virus is known to have been present in the past year, and avoiding other animals that have caught the virus.
However, the biggest problem with Parvo is how resilient it is to destruction. It can live in the environment for many months, and even survive disinfecting cleanings. It is simply resistant to most typical disinfectants.
In many cases it is smarter to throw out infected toys, food bowls and water bowls rather than trying to clean them.
Further, you need to be sure to properly clean all shoes that might have walked through infected areas, as well as carpets and floors. The virus can live in these areas for a long time after a dog with the virus has passed through.