As I said earlier, maybe the case jump is due to assay testing of patients in the long term monitoring trials

From Forbes article today

http://www.forbes.com/2009/10/27/ms-...rtner=yahootix

"The test Yednock and his colleagues developed found that something like 50% of the patients have JC virus. There are eight cases of patients who developed PML where Elan and Biogen-Idec have blood samples going back long before the infection happened. All of those cases had JC virus antibodies in their bloodstreams a year before they got PML. "That's a pretty good starting point," says Yednock.

Elan has transferred the assay to a commercial laboratory, a step toward making it available to patients. The test, which uses antibodies to detect the presence of JC virus, could be done with just a saliva sample. It has not been evaluated by regulators or the larger scientific community, but the hope is that doctors might be able to use it to pick which patients are the best candidates for Tysabri therapy."

Chris