Encephalitis is an acute inflammation of the brain, often caused by a viral infection. It can also be caused by a bacterial infection, non-infectious inflammatory condition, or an abnormal immune response in which the immune system mistakenly attacks brain tissue. Mild cases of encephalitis mostly recover fully with treatment. However, it may be life threatening and very serious in certain cases, therefore, prompt treatment is required. It can affect people of all ages, but mostly young and old are at higher risk.

Types of Encephalitis

There are basically two types of encephalitis-

Infectious-

Infectious encephalitis is also known as primary encephalitis. It occurs as a result of seizure of the brain by pathogens. The most common cause is a virus. Other organisms that can cause encephalitis include bacteria, parasites and fungi.

Autoimmune-

This type of encephalitis is caused when the immune system mistakenly attacks the brain. This is called autoimmune encephalitis.

According to the medical research, it is estimated that 40% of cases of encephalitis are infectious, 20% are autoimmune and about 40% are caused by unknown causes.

Causes of Encephalitis

Encephalitis can be caused by viruses and bacteria, including those transmitted by mosquitoes and other arthropods. Depending on what is causing the infection, the condition can develop suddenly or slowly. Following are the causes of Encephalitis-

Arbovirus-

This refers to viruses carried by insects and ticks. There are several types of mosquito-borne arboviral encephalitis. These include Western Equine, Eastern Equine, St. Louis and LaCross encephalitis. Arboviral encephalitis is often mild, it can be very severe and is often associated with permanent neurological damage.

Herpes simplex encephalitis (HSE)-

Herpes simplex can lead to encephalitis in some people. It is considered the most serious type because it can cause significant neurological dysfunction. It often affects the elderly and very young children.

Rabies-

In some underdeveloped and developing countries, cases of encephalitis can be caused by rabies, a virus that is transmitted by certain animals including dogs, raccoons, and foxes. If left untreated, this condition can lead to severe encephalitis, which can be fatal.

Risk Factors for Encephalitis

Factors that can increase your risk of disease include-

• Age- Infants and the elderly have a higher risk of developing encephalitis. It is more common than the herpes simplex virus in people in the 20-40 age group.

• Low immunity- Patients who have HIV/AIDS, take drugs to suppress immunity, or have other conditions that cause a weakened immune system are at higher risk.

• Geographical Distribution and Season- Encephalitis is more susceptible in geographic areas where mosquitoes or tick-borne viruses are common. They also contribute to the spread of encephalitis.

Symptoms of Encephalitis

Mild cases of encephalitis usually cause fever, joint and muscle pain, headache and a general feeling of weakness. Some patients also experience sore throat, muscle rigidity, upper respiratory infection, confusion, and lethargy.

In severe cases, the patient may suffer from-

• Cramps.
• Personality changes.
• Double vision.
• Crossed eyes.
• Increased intracranial pressure.
• Motor dysfunction.
• Partial paralysis.
• Seizures or loss of consciousness.
• Hearing or speech problems.
• Nausea.
• Irritability.

How to diagnose Encephalitis?

To diagnose encephalitis, the doctor reviews the patient's medical history and performs a physical examination. Patients are also frequently asked about their travel history to identify the cause of their disease. Depending on the results of these tests, your doctor may also prescribe-

• Blood and urine test.
• Computed tomography (CT) or magnetic resonance imaging (MRI) of the brain- showing detailed images of brain structures and showing abnormalities.
• Electroencephalogram (EEG) is used to detect irregularities in the electrical activity of the brain.
• Enzyme-linked immunosorbent assays (ELISA) Capture ELISA (MAC-ELISA) can identify which virus causes encephalitis immediately after infection.
• Polymerase chain reaction (PCR), can be used to identify viral DNA.
• Spinal tap, also called lumbar puncture, collects a small amount of fluid (cerebrospinal fluid) that surrounds the brain and spine. The sample is then examined in the laboratory for infectious agents.

Treatment for Encephalitis

Mild Encephalitis requires the following treatment-

Bed rest-

Several medications are prescribed by doctors to the patient during bed rest. Anti-inflammatory drugs such as acetaminophen, ibuprofen, and naproxen sodium may be used to relieve headache and fever.

Antiviral drugs-

Encephalitis caused by several viruses requires antiviral treatment. The antiviral drugs listed below are used to treat encephalitis-

• Acyclovir.
• Ganciclovir.
• Foscarnet.

Some viruses, including insect-borne viruses, do not respond to this treatment. Antiviral drugs are well tolerated. Kidney damage is rare as a side effect to it.

Treatment for Severe Encephalitis includes-

• Breathing support.
• Ensure adequate hydration and essential minerals.
• Corticosteroids help reduce swelling and pressure in the skull.
• Phenytoin helps to stop or prevent seizures.
• Physical Therapy is also useful to improve strength, flexibility, balance and mobility.
• Occupational Therapy uses adaptive products to support you in your daily activities.
• Psychotherapy is also a great measure to acquire behavioral skills to improve mood disorders and personality changes.

When to see a doctor?

If you experience severe symptoms of encephalitis, seek medical attention immediately. Do not ignore severe headache and impaired consciousness with this disease. If an infant or child has signs of encephalitis, make an appointment with a doctor.