In 20 years of Collie breeding, I've never had a case of parvo because I take precautions. Bleach kills the parvovirus, so I clean all puppy areas with it daily. I allow no contact with strangers until the puppies have had at least one series of vaccines and I give them myself at home. I take my shoes off before entering the puppy room and wash my hands before handling them, which I do every day for socialization reasons and to move them while I clean their whelping box. The Vet office is where people take sick puppies and the virus can be acquired there.