As Marc pointed out, some prescribing neurologists are attempting to be much more proactive in this regard than others are.

The problem is that there is no fool-proof method for determining if someone has PML, even when it is the person is highly suspected (showing obvious clinical signs) of having it.

For instance, in the case of one of the European patients who came down with PML, he was originally suspected of having it, so his CSF was tested. The result came back negative, but his doctor didn’t trust the results and treated him with plasma anyway.

When he continued to decline, he was given another CSF test and it came back positive this time:

http://www.sec.gov/Archives/edgar/da...14958ke8vk.htm

Cherie