A lot depends on what you are dealing with, so getting testing would be a good idea.does the disease stay on the ground aswell or just on the chickens
Generally - yes. The disease would be on the ground, in dust/dander, feathers, your shoes/clothes and equipment as well as the birds. Each disease has a timeline of how long it can last in the environment once the birds are removed. Some for a few days on up to months. Hopefully you will find some helpful information in the links below.
Common Poultry Diseases http://edis.ifas.ufl.edu/ps044
Info on transmission, how long it lasts in the environment, etc http://edis.ifas.ufl.edu/vm011