Mastadenovirus is a genus of viruses in the family Adenoviridae. Humans and other mammals serve as natural hosts. There are 51 species in this genus. The genus as a whole includes many very common causes of human infection, estimated to be responsible for 2 to 5% of all respiratory infections, as well as gastrointestinal and eye infections. Symptoms are usually mild. Canine adenovirus 1 (CAdV-1) can lead to death in puppies, or encephalitis in other carnivore species.