SciGuy2, no, I did not re-introduce the clam to a tank that was infected. It was placed in a tank that has never housed clams at all.
Today, the clam looks to be almost dead. It is receded and the mantle looks like its about ready to separate from the shell. I would guess it'll be dead by tonight. The tank I pulled it from has developed something odd. The original tank also has signs of this oddity, but they are few and far in between now since it has not housed a clam for a few weeks.
The oddity is what I'd best describe as white strings attached to things here and there. The strings look like when hair gets into he aquarium and gets coral mucus on it, but unlike hair, they are easily broken and cannot be pulled out. These are not like the mucus coming from the clam; rather, they form definite white strings of 1 to 2 inches in length. I am almost certain they are associated with the clam deaths since I have never seen them before and I've seen them coming directly out of the sick clam. saltkreep also noticed strings from tips of his acros that were not opening. I don't notice the strings necessarily only on the acros, but I do see them on the acros as well. These strings should be analyzed in my opinion.
Here is a pictures of some about 1" long strings:
<img src="http://home.attbi.com/~domitron2/reefcentral/misc/strings.jpg">