Seems to be a risk if pet birds are outside. It lives in an infected bird's throat and is transmitted to food and water sources. Birds can pass it regurgitating and feeding each other and birds of prey catch it eating infected birds. It is also passed in feces. Wild infected birds can deposit/leave their droppings in outdoor aviaries and cages when they fly over and that seems to be how the pet birds get it.The infected poop gets in the water and food dishes or the pet birds come in contact with it.