If a dog has been infected with Parvo the dog will experience weight loss that is rapid.
Other signs that your dog has Parvo are Vomiting, Lethargy. Blood in diarrhea, loss of appetite and Malaise which is discomfort associated with illness.
If you think your dog or puppy has Parvo you need to get it to the vet as soon as possible so it will have a chance at survival if they get a Parvo shot and are treated for the Parvo in time.
There's no guarantee that your dog will survive but if you do get the dog to the vet soon then it stands a better chance at surviving the Parvo disease.
You can kill off Parvo by spraying the yard with bleach. Bleach is the only known thing that will kill off the Parvo Virus.