Hi,
This sounds more like these kitties are getting into something than a disease. If you have any plants,carpet powders, toilet bowl cleaner, antifreeze etc, I would remove it from their areas. I would also bring them in. There is something dangerous outside.If you have any creeps for neighbors, they can be throwing them something.
Cats do get shots specially if they go out. The most important is called FVRCP and protects against distemper.
You must get them eating and hydrated. Try canned cat food or even tuna. Give them unflavored pedialyte by dropper - about two cc's every ten minutes for a half hour.
Please let me know how the babies are doing. If you still have questions, I will be happy to help.
Very sincerely,
Terri
Feline Healthcare Expert
Expert in feline health and behavior. 20 years experience with cats.