I've never had a blood test for JCV.

You and your doc should know that about 80% of the world population carries the JC virus in their kidneys and bloodstream. It's when it breaches the blood-brain barrier that it becomes a problem and to test for THAT, you need to have an LP and have a good technician who does NOT contaminate the spinal fluid with any blood from the stick.

There are clinical signs that will show up if someone has PML. They can mimic the signs and symptoms of a relapse. Having an MRI and a radiologist who is familiar with the different shape and presentation of the lesions associated with PML is important too. Unless a radiologist has seen PML MRIs they may not be familiar with the presentation of PML. Most of them see it when they do MRIs on AIDS patients with PML.

My neuro told me that if there are ANY sudden changes in my vision, thinking, and usual AFFECT that I should call immediately. That is the sum total of PML protocol at the beginning. What comes after is a whole different ball game. It would be MRI, LP and whatever else comes, including ceasing Tysabri and more than likely a plasma exchange to rid the body of Tysabri. It is my understanding that the PEx would only take place if the person was within a certain amount of time since their infusion.

Today was the two year anniversary of Tysabri's return to market. There are 30,000 people +- on Tysabri worldwide with NO incidences of PML reported since it's return.

Good Luck and please let us know how it goes for you!!