No, you don't need to isolate. It's not contagious. BUT, that being said, you will , should, treat your whole flock. I use ivermectin (I think that's how it's spelled), just a pea size will do. You can put it on a piece of bread, or any treat that they like. I used mini animal craqckers, but that's what they LOVE, and I knew they'd take it. Ivermectin is a horse wormer, that's why you don't need very much. You can get it at your local feed supply store. It's around $15-20 .
Jen
Jen