The DA2PP vaccine is actually four vaccines in one protecting against Distemper, Adenovirus Type 2 (Hepatitis), Parvo, and Parainfluenza. Distemper - This is a highly contagious and potentially fatal disease that begins in the respiratory system of dogs but can go on to affect other areas.  Adenovirus Type 2 - This infectious disease, previously known as hepatitis, affects the respiratory system of infected dogs. Parvovirus - Parvo is a highly contagious, life-threatening virus that causes severe gastrointestinal effects in dogs and can be fatal, especially in puppies. Parainfluenza - This disease affects the respiratory systems of dogs causing coughing, fever and more. It has been a known cause of kennel cough in dogs.