I tested positive for JCV antibodies and have an index value of 1.68. Is this considered a high value? I was just in to my neurologist with right side weakness and vision issues and cognitive concerns. She is also sending me for new MRIs. I have never been on Tysabri. Do I have reason to be concerned about PML?
PML is an extraordinarily rare condition but over 50 % of the population test positive on JCV antibody testing. We estimate that 80-90 % of people have been exposed to the JC virus and the virus remains dormant in their body, often in the kidneys. This is harmless. Tysabri may increase your risk of PML after 2 years of treatment but even then the risk is no more than 1%.
Unless you are significantly immunosuppressed for some other reason (chemotherapy or HIV infection), you have no reason to be concerned about PML. Your symptoms are likely related to your MS.
Revere (Rip) Kinkel MD
Director of the Multiple Sclerosis Program
Director of Hillcrest Neurology
Professor of Clinical Neurosciences
University of California San Diego