I never had pml people telling me tysabri cause it. What should I do. I'm worry. Should I switch medication infusion.
That's why they test for jcv (john Cunningham virus) JCV is a common virus that can cause PML in people who have weakened immune systems, such as people taking TYSABRI. Before or while you receive TYSABRI, your doctor may do a blood test to check if you have been infected by JCV.
Pml is rare.