Pacheco's disease is a viral infection to which only psittacine birds are susceptible. The susceptible birds are often young and affected birds usually have been stressed. This disease occurs worldwide and is also known as inclusion body hepatitis of psittacines. The order Psittaciformes (psittacines) characteristically has curved beaks and feet in which 2 toes are forward and 2 toes are back. Common pet birds in this order include: parakeets, parrots, macaws, cockatoos, cockatiels, lovebirds, lorikeets, and conures. Man and poultry are not affected by Pacheco's virus.