what causes autoimmune encephalitis
Causes of encephalitis. Encephalitis is usually the result of an infection. In many cases this is caused by a virus, but often no cause is found. In the UK, the most common viruses linked to encephalitis are: 1  the herpes simplex viruses, which cause cold sores and genital herpes.2  the varicella zoster virus, which is responsible for chickenpox and shingles.n many cases this is caused by a virus, but often no cause is found. In the UK, the most common viruses linked to encephalitis are: 1  the herpes simplex viruses, which cause cold sores and genital herpes. 2  the varicella zoster virus, which is responsible for chickenpox and shingles.