A well-written article published on GreenMedInfo describes a child who was given the MMR vaccine at the age of 18 months, and after a short life filled with adverse neurologic events eventually died at the age of 5. The very same live attenuated mumps virus which was administered to him in his vaccination was found at autopsy in his brain. The original case study is reported in Acta Neuropathologica January 2017.
Did the mumps live attenuated virus cause the child's encephalitis? No question, DNA sequencing says the same virus was found in the child's brain as was found in the vaccine. Did the fact of being vaccinated cause the encephalitis? Or did the vaccine somehow manage to attack the child's immune system so that he developed Severe Combined Immunodeficiency, which then allowed the attenuated virus to take over his body? Or did the child in fact have immunodeficiency before he was ever vaccinated? That is not so clear, at least not from this article.
The child was not diagnosed with immunodeficiency until 4 months after receiving the vaccine. At that point he received a bone marrow transplant which was apparently successful. However subsequently he developed low blood counts and was given rituximab therapy. Rituximab (Rituxan) is used for therapy of leukemias and lymphomas and helps the immune system destroy both normal and cancerous white blood cells. Rituximab is also known to be associated with re-activation of dormant hepatitis B infection. Perhaps it reactivated a dormant mumps infection. The authors concluded that perhaps "partial escape of virus from immune surveillance through specific mutational changes may have occurred", but make no mention of the use of the Rituxan.
No definite answers in this article – but certainly it raises questions about the safety of the vaccines which we routinely use on our infants.
Causation by temporal proximity is tempting to conclude, but certainly would not hold up in a court of law, or in accordance with the tenets of evidence based medicine.
So to conclude that the vaccine was the root cause of the encephalitis is premature and unjustified. It seems to be equally possible that the rituximab destroyed the very white blood cells that were active against the mumps virus that had been injected into the child with his routine MMR vaccine, and which would normally have protected the child against viral infection. What caused the immune system deficiency in the first place is still an unanswered question. Also unanswered is the question of why the mumps virus would have persisted in the child's brain unless either (a) the attenuated virus is not as friendly as we think it is or (b) the attenuated virus is capable to mounting a mortal attack on our immune system and (c) the child was already affected by as-yet-undiagnosed immunodeficiency.
I hope that there will be research into the effect of this live attentuated mumps virus on the immune system. I suspect that is where we may find some answers.