My dog and her littermates had parvo -- three lived, three died. It's a sad 50/50 chance, but nowadays with the amount of knowledge we have, it's getting easier and easier to treat. When he comes home he could relapse (as two of my dog's siblings did), so make sure that the puppy is kept very hydrated, and the food should be easily digested and palatable. I recommend a blended mixture of boiled chicken and boiled white rice with canned 100% pumpkin (not the pie filling, no sugar added) and parsley for atleast a couple of weeks. If you find any products that boost the immune system I highly recommend those --- my dog was given Immunex, a herbal mixture, and I still give it to her.
Good luck, and lots of prayers coming from over here in Canada.