I thought of this thread when I received a Gmail from Harbor Freight recently. Irregardless of contagious avian diseases, I have a good use for these when I don't want to risk stepping in poop while inside coops wearing my "good shoes." $9.99 for 50pr seems like a good price.
https://www.harborfreight.com/work-bootshoe-covers-50-pk-58664.html
https://www.harborfreight.com/work-bootshoe-covers-50-pk-58664.html