I have been on tysabri for nearly 3 years now and it has been great.i saw my neuro a month ago and he mentioned this JC virus and that i needed a blood test to see if i had this virus,anyway i had a letter from my neuro today saying that i tested positive for this jc virus and my chances of developing PML are now 1 in 385 and it was my choice if i wanted to stay on tysabri.i have spoke to my nurse regarding this and her reply was that nearly everyone tests positive for this jc virus and not to worry about it and carry on as normal,i am due for my next dose of tysabri next Friday and cant stop thinking about this now.

Has anyone else been in this dilema and what was your outcome ?

Thanks Simon

My test came back negative and as I have already had treatment with another DMD my chances, had it been positive, would have been lower than yours.

I have no idea what I would have done. Sorry.


Hi Simon

I’ll be on Tysabri 4 years in August I haven’t had the test I don’t really care if I have it or not I’d rather not have it to be honest more people have the JC virus then not anyway.

If your on Facebook you could join the UK tysabri group there’s quiet a few have tested positive for the JC virus and are still on Tysabri you could ask them how they feel.

If your interested in The group its called UK Tysabri users (Natalizumab) its a close group so no one only members can see your posts


Thanks Mark i have now found it on facebook,it looks good


Simon I have not had a JC test, so I don’t know how I would react if it came back positive.

My guess is that I would decide that the considerable benefits of being on Tysabri outweighed the not tiny (any more), but still small, risk of something horrible happening on the PML front, and that I would accept a 384 out of 385 chance of not getting PML. But that’s me guessing in the abstract - you are the one with a real decision to make, and that is another matter.

For what it is worth, I think that the PML threat is generally considered to be at its highest in the third year of treatment and that it starts to tail off after that, so if I’m right about that, you are already approaching theoretically calmer waters.

I think it would be a good idea for you to contact your nurse and explain your concerns and get a little more help from them on this (rather than just a breezy reassurance.) It is an important decision for you, and you need to feel confident that you are getting the right kind of support.



I’m trying to fight the curse of the moderator’s reply and bringing this post back to the front page

LOL AnnieB. I know what you are doing and I am sure efb will appreciate what you are trying to do

For those who have no idea what this comment is about, efb has been struck with a strange bug that makes any post she replies to change pages and thus disappear from view!

As regards to the JC virus I can’t comment personally except to agree with the suggestion of speaking with your MS Nurse again and not let her fob you off.

Best of luck with your decision.