Coccidia is not anything that you need to cull anyone over. They get it from the dirt and it is a common problem in young chicks. Corid is the medication that you give them to treat. It works quickly and very well. It is deadly and contagious but once it is treated, it is gone.
They are...
Any sneezing? any other changes?
If no sneezing, runny noses, or other respiratory symtoms, besides the gasping, I would treat for coccidia. Corid in their water for 5 -7 days. If they have coccidia, it will save them all...if they don't, it won't hurt them.