vent gleet help? was given 11 chickens a couple weeks ago. not sure what to do

hi,

like it says i was given 11 chickens a few weeks ago from my neighbor. we live on the same property and she is moving soonish so she gave them to me. she explained their feeding to me, gave me all her equipment, etc. told me to clean the coop and nesting area every few weeks. the coop is usually open and they roam pretty freely most days.

she helped me diagnose vent gleet on one of the chickens. no other chickens are showing any similar signs. my neighbor said she had one get this a last year and she ended up dying before they knew what to do. she was not able to offer much help.

google said to quarantine and bathe the chicken. how would i do that exactly? i’m cleaning the coop of course, i change their water every day all ready. how exactly do you bathe a chicken? can anything about vent gleet be passed to humans? what sort of space is good to quarantine them?

what products or practices in the future can prevent this from happening again also?

thanks in advance. i want to help them i just don’t know how to yet.