This is an argument for never buying started birds unless you are darn sure of their health status and disease history. Inconvenient? Yes, it is. Keeping a closed flock takes longer to get what you want because it involves hatching your own eggs or buying from established hatcheries and growing them out yourself. Even then, nothing is entirely foolproof, since some diseases can be passed through the egg, though not as many as are contracted through dander, etc.