Parvo is not exclusive to puppies though it is most commonly seen in them because they are at high risk until they have finished their sets of puppy shots and may be more protected against it. Nothing is a 100% guarantee but dogs unvaccinated or having an immune system not up to par (both of which describe pups who aren't old enough to have had all of their puppy sets) and things like that are very high risk. It is a highly contagious and severe viral infection (Gastroenteritis) which is species specific. Survival rates are very low without quick diagnosis and prompt treatment of the symptoms and required supportive care. If caught quickly enough within a day or two of even mild symptoms many vets are seeing improved rates with the use of Tamiflu and some other products (homeopathic) that may help at early onset of the symptoms. Here is some information for you.
www.merckvetmanual.com
www.dogfoodanalysis.com
www.merckvetmanual.com
www.dogfoodanalysis.com