What is Encephalitis?

Encephalitis is a medical condition where there is inflammation of the brain. The commonest cause of Encephalitis is viral infections. The symptoms of Encephalitis are similar to symptoms caused by flu, such as severe headache or fever. Other symptoms of encephalitis include disorientation, seizures or difficulty in movement or thinking. However, there are many patients suffering from encephalitis who experience no symptoms or only mild flu-like symptoms. A severe case of encephalitis can be a life-threatening condition, albeit it is rare. The course of different cases of encephalitis is difficult to predict. For this reason, it is important get correct diagnosis and treatment on time for Encephalitis.

What is Encephalitis?

Causes of Encephalitis

The exact cause of encephalitis is usually not known. The common diagnosed cause is often a viral infection. The causes of encephalitis include noninfectious inflammatory conditions and bacterial infections. As mentioned above, infection can cause encephalitis and can lead to any one of the two given below conditions, which affect the brain:

  • Primary encephalitis develops when there is direct infection of the brain from a virus or other infectious agent. This infection can be widespread or can be localized in one region. A primary infection can also occur as a result of reactivation of an inactive virus, which has remained latent or inactive after an old illness.
  • Secondary or post-infectious encephalitis occurs as a result of a reaction of a defective immune system as a response to an infection occurring somewhere else in the body. Instead of only attacking the infection causing cells, the immune system mistakenly attacks the healthy cells of the brain. Secondary encephalitis can also usually occur about 2 to 3 weeks after an initial infection. In rare cases, secondary encephalitis occurs as a complication of live virus vaccination.

Common Viral Causes of Encephalitis

  • Encephalitis Caused by Enterovirus: These viruses include the coxsackie virus and poliovirus, which often results in illness with symptoms similar to flu, such as abdominal pain and eye inflammation.
  • Encephalitis Caused by Herpes Simplex Virus (HSV): This virus is of 2 types. HSV-1 commonly causes fever blisters or cold sores around the mouth and HSV-2 is responsible for genital herpes. Encephalitis occurring from HSV-1 is rare, but when occurs, it can potentially cause severe brain damage or death.
  • Encephalitis Caused by other Herpes Viruses: This includes varicella-zoster virus, which is responsible for causing shingles and chickenpox; and the Epstein-Barr virus, which is responsible for causing infectious mononucleosis.
  • Encephalitis Caused by Mosquito-Borne Viruses: This includes arthropod-borne virus or arbovirus, which is transmitted by mosquitoes and other such blood-sucking insects. Infections which occur as a result of mosquito-borne viruses include La Crosse, West Nile, St. Louis, eastern equine and western equine encephalitis. Symptoms of the infection start to appear in a few days to two weeks after the patient has been exposed to an arbovirus.
  • Encephalitis Caused by Rabies Virus: The rabies virus causes infection after a bite from the infected animal, after which patient rapidly develops encephalitis. However, in USA, rabies is a rare cause of encephalitis.
  • Encephalitis Caused by Tick-Borne Virus: This includes the well known tick-transmitted virus, the Powassan virus, which is responsible for causing encephalitis. Patient starts experiencing symptoms in about one week after he/she has been exposed to the virus.
  • Encephalitis Caused by Childhood Infections: Some common infections occurring in childhood, such as mumps, measles, and German measles often are a cause of secondary encephalitis. Due to the development of vaccines for these diseases, these causes have now become rare.

Risk Factors of Encephalitis

  • Young children and older individuals are at an increased risk for having most of the types of viral encephalitis.
  • Individuals, who are aged between 20 to 40 years, are at a greater risk for having encephalitis caused from herpes simplex virus.
  • People living in certain geographic regions, where tick-borne or mosquito-borne viruses are prevalent, are more prone to having related encephalitis.
  • Weakened or compromised immune system, such as seen in individuals who are taking immunosuppressants and who are suffering from HIV/AIDS, are at increased risk of encephalitis.
  • Diseases resulting from mosquito or tick bites are more common in summer, spring and early fall. So in these seasons, the risk for having encephalitis is more. Warmer regions in America have ticks and mosquitoes present all throughout the year.

Signs & Symptoms of Encephalitis

In majority of the patients, viral encephalitis produces mild flu-like symptoms or does not produce any symptoms at all. The mild symptoms which are similar to flu are:

Signs & Symptoms of More Severe Encephalitis include:

  • Agitation, confusion, hallucinations.
  • Seizures.
  • Muscle weakness.
  • Paralysis or loss of sensation in certain regions of the face or body.
  • Double vision.
  • Hearing problems or speech problems.
  • Perception of foul smells, such as rotten eggs or burned meat.
  • Loss of consciousness.

Signs & Symptoms of Encephalitis in Infants and Young Children include:

  • Nausea.
  • Vomiting.
  • Bulging in the fontanels or the soft spots in the skull of the infants.
  • Inconsolable crying.
  • Stiffness in the body.
  • Not feeding adequately or not waking for a feed.
  • Irritability.

Complications from Mild Encephalitis

The complications occurring as a result of encephalitis depend on various factors, such as age, the severity of the illness, the cause and the time from the onset of the disease till the initiation of the treatment. Most of the patients, who are suffering from a mild case of encephalitis, recover in a few weeks and have no long-term complications.

Complications of Severe Encephalitis

Inflammation which causes injury or damage to the brain can cause many complications, some of which can even lead to coma or death. There are other complications of Encephalitis of varying degrees, which can be present for many months or can be permanent. These include:

  • Weakness or lack of muscle coordination.
  • Persistent tiredness or fatigue.
  • Changes in the personality.
  • Paralysis.
  • Problems with memory.
  • Vision or hearing defects.
  • Impairments with speech.

Diagnosis of Encephalitis

Medical history and physical examination of the patient are done to arrive at the diagnosis of Encephalitis. Other than this, investigations done for confirming the diagnosis of encephalitis are:

  • Brain imaging tests, such as Magnetic Resonance Imaging (MRI) or Computerized Tomography (CT) scan, help in revealing if there is any swelling on the brain or some other medical condition, such as a tumor, which is causing the symptoms. MRI and CT scan helps in assessing the internal region of the brain by producing detailed 3-D images of the brain or cross-sectional images of the brain.
  • Lumbar puncture or spinal tap is a procedure where a needle is inserted into the lower back to extract CSF or cerebrospinal fluid and sent to lab for testing. Any changes in this fluid may indicate inflammation and infection in the brain. CSF is the protective fluid, which is present around the brain and spinal cord. Testing of CSF can also help in identifying the virus or other infectious agents responsible for encephalitis.
  • Electroencephalogram (EEG) is a test where multiple electrodes are connected to the scalp and the EEG records the brain's electrical activity. If there are any abnormal patterns present, they can help in diagnosis of encephalitis.
  • Blood and urine tests or testing the secretions from the back of the throat can be done for identification of viruses and other infectious agents.
  • Biopsy of the brain can also be done where a small sample of tissue of the brain is removed and sent to lab for testing. This procedure is done rarely and is done in cases where the patient's symptoms are exacerbating and there is no response to treatments.

Treatment for Encephalitis

  • In mild cases of encephalitis, where the symptoms can be mistaken for flu, treatment primarily comprises of: Bed rest, lots of fluids and anti-inflammatory medicines, such as acetaminophen, naproxen and ibuprofen. These medicines help in relieving fever and headaches.
  • Antiviral medicines are given in cases of encephalitis, which is caused by certain viruses. Intravenous antiviral treatment is usually given and these medicines consist of acyclovir, foscarnet and ganciclovir.
  • There are some particular viruses, such as insect-borne viruses, which do not respond to these types of treatments. In cases where a specific virus is not immediately identified, then immediate treatment with acyclovir is usually started. This medicine is often effective against the herpes simplex virus, which can cause encephalitis or even death if ignored.
  • Antiviral drugs have side effects, such as diarrhea, nausea, vomiting, and pain/soreness in the joints and muscles. Other rare, but serious side effects can include abnormalities in the function of the liver or kidney and suppression in the activity of the bone marrow. The patient is observed and tests are done to monitor the patient for serious side effects.
  • Corticosteroids can be given to reduce the pressure and swelling in the skull.
  • Phenytoin is an anticonvulsant medication, which can be prescribed to prevent or stop the seizures.
  • Supportive care is needed for patients having severe encephalitis and it consists of: Intravenous fluids, so that the patient has adequate hydration and maintains the necessary levels of important minerals. Breathing assistance is provided along with careful monitoring of the function of breathing and heart.

Additional Therapy for Encephalitis

Additional therapy may be needed for Encephalitis patient after the initial illness abates. The type of therapy given depends on the severity and type of complications and can include:

  • Physical therapy for Encephalitis helps in improving the patient's strength, balance, flexibility, mobility and motor coordination.
  • Speech therapy helps the patient in relearning his/her control over muscle and coordination for producing speech.
  • Occupational therapy helps the Encephalitis patient in developing everyday skills and also helps in using the adaptive products needed for activities of daily living.
  • Psychotherapy for Encephalitis helps the patient in learning strategies to cope with their situation and in developing new behavioral skills for addressing personality changes and mood disorders. Medications can also be prescribed if necessary.

Prevention of Encephalitis

Taking precautions by avoiding exposure to viruses, which are responsible for causing encephalitis, is the best method of preventing viral encephalitis. This can be achieved by:

  • Practicing good hygiene by washing hands frequently and thoroughly with water and soap, especially before and after meals and after using the toilet.
  • Sharing beverages, tableware and utensils should be avoided in order to prevent transmission of virus and other infectious agents.
  • Vaccinations should be always kept updated by taking them on time and when needed. Before traveling to any place, doctor's advice should be taken regarding vaccinations for different places.

Tips for Protection against Ticks & Mosquitoes

  • Always dress, so that your body is covered and you are protected. Always wear long pants and long-sleeved shirts if you have to remain outside between the dusk and dawn. This is the time when the mosquitoes are at their most active. Also, it is better to avoid being outdoors at this time. Ticks are commonly found in wooded regions, which have shrubs and tall grasses and such places should be avoided.
  • Mosquito repellent can be applied to repel mosquitoes. Mosquito repellents can be applied to the skin as well as the clothes. Some of the ingredients in a mosquito repellent, such as lemon eucalyptus, are not recommended for children who are below three years of age. As these repellents are not recommended for infants, so mosquito netting should be used to cover the stroller or an infant carrier.
  • Children should always be assisted when using the mosquito repellant. Care should be taken to avoid application in the areas surrounding the eyes and ears. Always spray repellent on the hands and then should be applied to the child's face. Never apply repellent on the hands of young children, as they can put their hands in their mouths.
  • Always wash the skin where the mosquito repellant has been applied with soap and water after coming indoors. 
  • EPA-recommended insecticides containing permethrin are also recommended which helps in repelling as well as killing mosquitoes and tics. These insecticides can be sprayed on tents, clothing etc. Application of permethrin should never be done to the skin.
  • If there are any sick or dying animals/ birds outside your home, then it should be immediately reported to the local health department.
  • It is important to get rid of standing water near your home, such as in the yard, where the mosquitoes usually lay their eggs. Areas where standing water is present include gardening containers, such as flowerpots, old tires, flat roofs and clogged gutters. The mosquitoes present in the standing water can be controlled by filling the ornamental pools with mosquito-eating fish. Mosquito dunks are products, which kill the larvae of the mosquitoes and can be used in ponds, birdbaths and barrels for using garden water.

Written, Edited or Reviewed By:


Last Modified On: May 4, 2016

Pain Assist Inc.

Pramod Kerkar
  Note: Information provided is not a substitute for physician, hospital or any form of medical care. Examination and Investigation is necessary for correct diagnosis.

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