World Encephalitis Day: Raising Awareness of a Serious Brain Infection
Today, February 22, is World Encephalitis Day, a global awareness day for people who have been affected by encephalitis, an inflammation of the brain. Encephalitis can be caused by various infections, such as viruses, bacteria, fungi, or parasites, or by autoimmune disorders. Encephalitis can lead to serious complications, such as seizures, memory loss, cognitive impairment, or even death. According to the Encephalitis Society, a UK-based charity that founded World Encephalitis Day in 2014, about 500,000 people are affected by encephalitis every year worldwide, but many cases are not diagnosed or reported.
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.
Comments