any infectious disease transmitted between humans and other vertebrate animals. The term was originally defined to describe a group of diseases that humans may acquire from domestic animals. This definition has been modified to include all human diseases that are acquired from or transmitted to any other vertebrate. Examples include rabies (from small mammals such as the dog, fox, bat, and rodent), tularemia (from rabbits and wild rodents), psittacosis (from birds of the parrot family), glanders (from horses), anthrax (from ruminants, horses, and swine), brucellosis (from domestic livestock), and a variety of respiratory infections from domestic animals and house pets.