Encephalitis affects nearly 500,000 people of all ages worldwide each year, according to the Encephalitis Society, with young children and older adults most vulnerable. Other risk factors include having a compromised immune system, living in certain areas of the world and the season of the year.
Encephalitis is inflammation of the brain. While the exact cause of encephalitis often is unknown, when a cause is known, it's most commonly a viral infection.
Viruses that can cause encephalitis include herpes viruses and enteroviruses. Childhood infections, such as measles, mumps and rubella, used to be a common cause of secondary encephalitis, but this is rare now in the U.S. due to the availability of vaccinations for these diseases.
Most people with viral encephalitis have mild flu-like symptoms, including headache, fever, achiness and fatigue. Sometimes the signs and symptoms are more severe, and can include confusion, agitation or hallucination; seizures; and loss of sensation or paralysis.
In some cases, encephalitis can be life-threatening. Timely diagnosis and treatment are important because it's difficult to predict how encephalitis will affect each person.
Treatment for mild encephalitis usually consists of bed rest, fluids and anti-inflammatory medications to relieve headache and fever. Encephalitis caused by certain viruses usually also requires treatment with antiviral medications.
People who are hospitalized with severe encephalitis might need breathing assistance, IV fluids, anti-inflammatory drugs to reduce swelling and pressure within the skull, and anti-convulsant medications to stop or prevent seizures.
