What is encephalitis?
Encephalitis is an inflammation of the brain. While it can happen when the immune system mistakenly attacks tissues in the brain, it’s more commonly a result of a bacterial, fungal or viral infection. Viruses are the most likely cause of encephalitis, especially:
- Common viruses. The herpes simplex virus can cause one of the most dangerous forms of encephalitis and can lead to severe brain damage. The Epstein-Barr virus, HIV and cytomegalovirus can also cause encephalitis
- Childhood viruses. While vaccines have made these forms of encephalitis fairly rare today, the chickenpox, measles, polio and rubella viruses can still cause encephalitis.
- Arboviruses. These viruses are carried by insects, usually mosquitoes or ticks. They are most common in the West, Midwest and Southern regions of the U.S. Drinking unpasteurized milk from tick-infected goats, sheep or cows can also cause encephalitis.
Encephalitis is a brain condition that typically affects children and older adults, as well as people with compromised immune systems. People who are living with HIV are particularly at risk, with around 15% of all encephalitis cases happening in this population.
Encephalitis is rarely life-threatening. However, each person responds differently to this condition and it’s vital to get a diagnosis and begin treatment as soon as possible.
What are the symptoms of encephalitis?
Encephalitis may be hard to recognize at first, since the symptoms are similar to those of the flu. Initial symptoms include headache, fatigue, fever and aches in muscles and joints.
While encephalitis is not usually life-threatening, it is very serious. It’s important to get immediate care if you or a loved one has any of the more severe symptoms of this condition, such as:
- General confusion
- Loss of sensation or paralysis in the face or body
- Muscle weakness
- Loss of consciousness
In young children and infants, the symptoms of encephalitis may be different. Infants may have bulging in their fontanelles (soft spots on the head), and babies and young children may have nausea, vomiting, body stiffness, irritability and difficulty with feeding. This age group should be seen immediately by a doctor if they have any symptoms of encephalitis.
How is encephalitis diagnosed?
A number of tests can help a doctor diagnose encephalitis. A neurological exam is usually the first test. It may be followed by a lumbar puncture (spinal tap) to collect a sample of cerebrospinal fluid. This fluid will be tested for white blood cell count, glucose, higher-than-average levels of protein, bacteria or viruses.
Brain imaging studies, such as an MRI, may be ordered to identify any changes in the brain that could point to encephalitis.
How is encephalitis treated?
For people with relatively mild symptoms, doctors will often recommend rest, plenty of fluids and a pain reliever such as acetaminophen to reduce fevers or headaches.
If symptoms are more severe, an antiviral medication will likely be used. One of the most successful antivirals is acyclovir, which is effective against a number of infections including those caused by the herpes simplex virus.
Can vaccines cause encephalitis?
Vaccines are essential for preventing many diseases and they save millions of lives every year. It’s rare for a vaccination to cause encephalitis, but it can happen.
The National Vaccine Injury Compensation Program includes encephalitis as a covered vaccine injury. People who have been injured by vaccines can be compensated under this program without paying any legal fees or costs.