I always have hand sanitizer near the chickens because even though I head straight to wash up with soap and water after doing anything with them I still have to touch doornobs, etc. on my way there so I use it just for precaution. Maybe your kids would at least put the sanitizer on after messing with the birds? Just a suggestions. I don't know if that is why they are sick but it couldn't hurt. I hope everyone gets better soon!