Question: Adrian do you know what the most harmful virus is that you can effect your brain.

Adrian Chu answered on 14 Nov 2016:

Many viruses can affect your brain, and your brain can be affected in different ways. My study involves a bacteria that can, in rare cases, infect the meninges (the layers that wraps up your brain, spinal cord etc.). For the actual inflammation of the brain itself, that is known as encephalitis.
Viruses that can cause encephalitis include herpes simplex virus, mumps, Ebstein-Barr virus, cytomegalovirus, HIV etc. In Asia there’s also a very deadly virus spread by mosquitoes known as Japanese encephalitis, caused by the Japanese encephalitis virus.
Each of them can be harmful in their own respective ways, so I’m not sure I can put a rank to their severity. In the rare occasion that any bacteria or virus reach your brain, they’re all equally deadly because inflammation in the brain area is certainly life-threatening.