where are April and Casey

[Leo's_Girl06]

Why havent they showed casey and april very much? Id like to see them more often.

[MikesPizzaShack]

right now there focusing more on the turtles and splinter..u know family stuff. april and casey will be in the show again soon. there gonna be on the 100th episode.

[Masked Ninja]

And I wonder how Casey is figuring into this. If the Turtles are avoiding their human friends, that's understandable. After all, Karai found and contacted April... the Turtles probably don't want to create more trouble than necessary for them.
This is my theory, at least.