if you mix one cup of bleach to 5 gllons of water you can spray teh coop including soil let dry throughly for 3 days and all viruses and contagions are gone, but you have to clean the coop first. scrub all surfaces with hot soapy water, rinse well and spray the bleach solution the next day. Bleach only works on clean surfaces, vinegar will do the same, but takes 3 minutes of sitting ton surface to work.