What is Encephalitis?
Encephalitis is an inflammation of the brain. It is caused either by an infection invading the brain (infectious encephalitis) or through the immune system attacking the brain in error (post-infectious or autoimmune encephalitis).
Anyone at any age can get encephalitis. There are up to 6,000 cases in the UK each year and potentially hundreds of thousands worldwide. In the USA there were approximately 250,000 patients admitted to hospital with a diagnosis of encephalitis in the last decade.
Causes of Encephalitis
The inflammation is caused either by an infection invading the brain (infectious encephalitis) or through the immune system attacking the brain in error (post-infectious or autoimmune encephalitis).
Viruses are the most frequently identified cause of infectious encephalitis (e.g. herpes viruses, enteroviruses, West Nile, Japanese encephalitis, La Crosse, St. Louis, Western equine, Eastern equine viruses and tick-borne viruses). Any virus has the potential to produce encephalitis, but not everybody who is infected with these viruses will develop encephalitis. Very rarely, bacteria, fungi or parasites can also cause encephalitis.
Some types of autoimmune encephalitis such as acute disseminated encephalomyelitis (ADEM) are caused by infection in which case the term ‘post-infectious encephalitis’ is used. Other forms of autoimmune encephalitis are associated with finding specific antibodies in blood such as VGKC complex (anti-LGI1 and Caspr2), NMDA receptor, GAD, AMPAR and GABA antibodies. Antibodies, also called immunoglobulins, are large Y-shaped proteins which identify and help remove foreign antigens such as viruses and bacteria.
The reason why these antibodies are produced by the immune system in people with autoimmune encephalitis is not known in most cases. Sometimes a tumour (benign or cancerous) may generate the antibody.
Brain and spinal cord injury
- Every 90 seconds someone is admitted to hospital with a brain injury
- 2.6 million people are living with the effects of traumatic brain injury or stroke
- 50,000 people are living with a spinal cord injury
Brain tumours
- More under 40s are killed by brain tumours than by any other cancer
- 12,300 people are diagnosed with a primary brain tumour every year
- 5,500 lives are lost to brain tumours every year
