Hi PL,

I've heard of other people having problems with infections, but I am one of those people who never gets sick. I've had a run in with salmonella and a ruptured appendix but the first was due to something I ate and the second was something that anyone could have!

When my doc does my bloodwork, I have slightly higher than normal WBCs, and he says that is from all the T cells milling around because they aren't getting into my brain anymore. He says all it does is block T cells from crossing the blood/brain barrier and damaging myelin, and that it doesn't block all of them but enough are blocked to stop damage.

I think that not enough is known to make a stand on what actually causes the JC virus to activate and cross the BBB. 80-85% of the population of the world carries the JC virus in their kidneys and it is usually dormant. PML has been seen in people with AIDS who are immune suppressed, in people who are treated with Rituxan, Tysabri, Raptiva, Cellcept, Methotrexate, Mitoxantrone, chemotherapeutic drugs, corticosteroids and some transplant drugs.

Because of the PML cases associated with Tysabri, more has been learned about PML than ever before. It was previously known as a fatal disease. Now, with plasma exchange along with treatment with mefloquine or mirtazepine, and steroids if IRIS develops, people are living after diagnosis of PML.

Reports on patients diagnosed with PML after Tysabri shows that most of the patients diagnosed so far are still alive. Some are doing well. Some of the earlier people are very disabled. The key seems to be increased vigilance and reporting ANY symptoms to your doctor. Since not many people are relapsing on Tysabri, when signs of relapse are seen, the new norm is to suspect PML first and vigorously test for it with blood tests, spinal taps, MRI, discontinuing Tysabri and further treatment if necessary. It COULD be just a relapse, but no one takes that chance now.

Sorry to be so long-winded but you did ask...