Our Sheba came to us with parvo. We got her from the SPCA and she'd had her first shots--I brought her home on a Thursday & she seemed okay, if quite docile--not unusual for a puppy in a new home. Friday she was very lethargic, not at all playful. Late that night she started throwing up, but we didn't know why. Next morning the lady at the shelter called to ask how was our puppy. I said sick--why, what's wrong with her??? She said parvo--one of Sheba's litter mates (already in a home) had died, and two others, still at the shelter, were sick. We took Sheba into the clinic right away and she stayed there until Monday. By Monday afternoon she was better--the vet said she could go home. When I went to get her and they brought her out she didn't look better--but as soon as she saw me she perked up. I was surprised she knew me, since she'd been here such a short time. She came home & was soon 100% well. Just that one pup died--the shelter pups that were at the vet clinic were sicker than Sheba was but they pulled through. Sheba lived a normal, healthy life--no after effects from having parvo when she was 3 months old.
As for expecting your vet to take responsibility for your pup getting sick, and reducing or deleting your bill--I'm afraid I wouldn't expect that. The clinics here will warn an owner if they've had a parvo case in the clinic recently. I have the vet come out to do my puppy vaccines--that way I know there will be no exposure to anything at the clinic. If I couldn't get the vet to come out I would take the pup in but ask the vet to come out to the truck to give the vaccines....and if a dog (any age, not just pups) goes into the clinic for anything (surgery, treatment, whatever) and hasn't had its parvo shots, the clinics make the owner sign a waiver, saying that they understand the risk of infection at the clinic, and will not hold the clinic responsible for any illness the dog may develop.
I realize that in an emergency situation you don't have a lot of options. I have called ahead & asked if the clinic has had any parvo dogs in recently & if they say yes I'll call a different clinic & ask the same question of them. I know the vets do their best to prevent the spread of any infection, but with parvo it's so hard to eliminate the virus from the premises they they can only try their best, with no guarantees.