Disease is not a concern, the raccoon killing your birds is the only concern.
And YES! Be very worried.
Sorry to say it but you've now got quite a problem on your hands, time to get to work!
Quite honestly I am surprised it didn't kill any birds or even your entire flock.
Next steps:
Find out how it got in & fix it, secure the your coop and run.
If your run does not have a top, add one.
Make sure your coop doors are lockable. Hardware clothe on all windows, not just window screen.
Now that they find your coop, they will come back.
Get a cage trap and start trapping and killing raccoons. Marshmallow, dry cat food, sardines are all good bait.
If you cant bring yourself to trap and kill them, call someone who will or hire a critter control company.
DO NOT relocate raccoons, it illegal in almost every state and quite simply irresponsible. Trap and kill.
I also recommend an outside dog. My chocolate lab hangs out with my hens and keeps all predators out of the area. Only time I ever lost a bird is when she was away for a week at the kennel.