They can get exposed to parvo from almost anywhere. House, yard, a human who has unknowingly been around it and tracks it into the environment, another dog that is shedding for whatever reason or actively has the virus. They are young and/or aren't fully vaccinated is usually a huge factor. It is extremely contagious.
Parvo can live a long time on inanimate objects. They recommend waiting to own a dog for a year after having parvo in your house. The dog could get it from the ground if a dog has been there recently so that is why they recommend not taking your new puppy out until it has had at least the first shots. It is very contagious.
Get it vaccinated.They can catch it almost everywhere.don't want to mess around the cost of the shot is less than what you will pay if your dog does come in contact with it...