How long does parvo virus last in a yard?

Question
4 years ago, I had a dog that died of parvo virus. I was wondering if there is a chance the virus might still remain in my backyard. If so, is there a chance that the virus can spread by my family walking into the affected area and then walking into an area that is not affected? The reason I ask is because right now I have a 1 yr and  3 month old dog who had puppies in which they are 2wks and 2 days. Right now I have them in my garage, away from the affected area, but I am afraid that if we walk from the affected area into the area that is not affected she can carry the virus to her puppies.

Answer
Parvo is a nasty virus that is extremely hardy. I have heard that it can survive heat and cold for at least a year. After four years, however, I would think it should have finally died out, but I would still be leary myself, if I were you. Losing one dog to parvo is certainly more than enough for anyone. I know one breeder who suffered with it when we first learned about parvo, and she said the only way to get rid of it is to move! Well, we know a bit more about parvo now.

Mix up a spray of one part chlorine bleach and 30 parts water, and use that to spray the bottom of your shoes and your hands before entering the house/garage. Some people will completely change their clothes before handling puppies. Yards can be spray with a solution of 4-8 oz. of bleach to one gallon of water.