Encephalitis is a disease referring to the inflammation or swelling of the brain. Broadly, it can happen because of infections, including viral infections, or the immune system acting up.
That’s why Dr. Sarosh Irani, a Mayo Clinic neurologist and researcher, says it’s essential to recognize World Encephalitis Day.
“A number of physicians, and certainly the public, are not aware of encephalitis as an entity. Yet, it is a medical emergency, where we know that early treatment makes a major difference to our patients, both with infectious forms of the disease and the growing — and perhaps now more common — autoimmune forms of the disease,” Dr. Irani says.
Types of encephalitis
The two main types or divisions of encephalitis are infectious and autoimmune. In some cases, the exact cause of encephalitis remains unidentified.
Important things to know about infectious encephalitis:
• It’s caused by viruses invading the brain, such as herpes and enteroviruses.
• Mosquitoes and ticks can also transmit viruses which can cause encephalitis.
• Symptoms develop quickly, over days to weeks.
Most people with infectious encephalitis start with symptoms such as headache and fever. These can progress to more severe symptoms within hours to days, such as confusion, personality changes, seizures, and loss of sensation or movement in specific body areas.
Important things to know about autoimmune encephalitis:
• The immune system mistakenly attacks the brain.
• It primarily targets people from their first year of life to late 80s, both women and men. Some forms preferentially affect young or old; males or females.
• It can be triggered by an infection elsewhere in the body (post-infectious autoimmune encephalitis) or a tumor (paraneoplastic autoimmune encephalitis). But in about 90% of cases, the cause is not found.
• Symptoms can develop quickly, as per infectious encephalitis, or more slowly, over weeks to months, and may not include fever.
• Those symptoms of autoimmune encephalitis may include changes in personality, memory loss, problems understanding reality (psychosis), hallucinations (seeing or hearing things that aren’t there), seizures and unusual movements.
Preventing encephalitis
Prevention is a significant challenge, says Dr. Irani.
“We do not have consistent preventive measures for these illnesses. Only a few infectious causes may be prevented with vaccinations. There are also a few causes of infectious encephalitis which we can prevent through limiting person-to-person spread or by trying to stop, for example, vectors like mosquitoes infecting some patients. But for autoimmune causes, we don’t know of ways to prevent this illness, yet this is a major question from all of our patients,” he says.
