The Parvo Virus has a pretty long lifespan as far as viruses go and the Parvo Virus can live up to a year in the ground.
To kill the Parvo virus you can buy a parvo virus killing solution at Home Depot or you can just mix chlorine bleach with some water in a pump up yard sprayer or in a pull behind lawn and weed sprayer and spray the chlorine bleach and water over the entire yard to kill the Parvo Virus.