Last reply 5 years ago
Stratify JCV

Just wondering how often people get tested for the JC virus?

I’ve been on Tysabri for nearly 6 months now, and was tested for the JC virus before starting (was Negative)…So I’m just wondering how often I should be tested for it/ or how often you get tested fo it?


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5 years ago

Hi there!
Important topic, am glad you are aware to ask – but I would really suggest bringing it up with your neurologist too!
Basically the JC test is done to evaluate risk of PML.
From the research I’ve done (I’m also on Tysabri) once you test positive, no more tests, positive for life.
If negative though, you can change. About 2% of people are infected with the JC virus each year – you wouldn’t even know, it’s like the common cold on first infection usually, so it is important to be retested.
From my research I understand it is recommended every 6months, until end of Tysabri, or status +.
This is important because all cases of PML (approx 320 to date) of people on Tysabri have occurred in JC+ people (where testing available, though as the JC virus causes PML you have to be + to get PML.)
There is one case of a patient who tested -, started Tysabri, tested + 13 months later, continued Tysabri, and got PML (I can’t find any other info on the case, such as if they had been on other immunosuppressants). THIS is why it is so important to be retested.
I would suggest you have a good chat with your neurologist till you both have a plan you are happy with.
The risk of PML in year 1 (even if JC+) is less then 1:10,000, but it is important to be aware of all the information, risks, Benifits, and be able to make an educated choice.
Good luck!

5 years ago

I just started Tysabri and the nurses at the hospital told me get tested every 3 mths. Before i started my neurologist said 6mths. I would do 3 mths even tho tested negative. I want to also get liver and tested, becue inmy own personal situation my liver as never been good and I just been feeling weaker.

5 years ago

I have been on tysabri for 2 years now and I have been tested 3 times now and having another in a week or so. So I guess twice a year, dude.

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