This might seem extreme, but if you find one or two of these little buggers, here is a cure. No Shrimp, no Juice, chemicals or otherwise.
I went do Canadian Tire and bought a mini tiger torch. (The ones that have a small blue flame about 1-2" in length. I took the rock with the offending coral and torched the crap out of the one small cavern that it was in. Not a sign of it is left. And as far as regrowth is concerned, nothing grows from carbon >
Now, before someone says nay about this. I can tell you I have 2 of these one a rock COVERED in zoo's. I lost no zoos. Because the flame from this torch is very precise, it just cooked the aptasia. REALLY RECOMMENDED.