Encephalitis Symptoms, Risk Factors, Diagnosis and Treatment | Narayana Health

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Encephalitis :

Symptoms, Causes, Diagnosis & Treatment



What is Encephalitis?

Encephalitis is a condition when the brain in a human body experiences inflammation. Many factors could lead to this condition, however, the most common factor is a viral infection. Encephalitis also occurs when the body starts attacking the brain cell tissues. Encephalitis is not a life-threatening disease, but its side effects include fatigue, headache, and fever. Encephalitis occurs in 1 of every 1000 patients affected by measles. Among the many forms, Japanese Encephalitis, Tick-borne encephalitis, Rabies, and Primary and secondary encephalitis.



Symptoms of Encephalitis

Depending on the severity of the condition, Encephalitis presents itself in various forms. In the early stages, the symptoms of Encephalitis include Fever, headache, nausea, sensitivity to light, and body pains. As the condition progresses, the patient experiences drowsiness, fatigue, stiffness in the neck, joint pains, and stiffness in the limbs. Patients with advanced stages of Encephalitis show symptoms like Confusion, disorientation, loss of speech, hallucinations, hearing problems and Coma.

In infants, Encephalitis presents itself in the form of lack of appetite, spots on the skull, vomiting and nausea and not feeding or not waking up to feed.



Types of Encephalitis

The major types of Encephalitis are:

  1. Japanese Encephalitis
  2. Tick-borne Encephalitis
  3. Primary Encephalitis
  4. Secondary Encephalitis

Japanese Encephalitis:

Japanese Encephalitis is a non-communicable disease that is caused by Flavivirus which is transmitted from the bite of a Culex mosquito. The Culex mosquito is the vector that transfers the disease from the host to new animals it feeds on. Birds are the most common hosts for this form of encephalitis. In this, the vector, the Culex mosquito acquires the virus from one animal that it feeds on and transmits it to the next animal it feeds on. Pigs and Horses are the most affected by this.
A vast number of cases in Japanese Encephalitis is seen in India, Cambodia, Vietnam, China, Japan, Indonesia, Myanmar, and Nepal.

A person infected with Japanese Encephalitis will show no immediate symptoms. The symptoms will be seen 5-15 days after the onset of the condition. The symptoms include:

  • Daze
  • Vomiting
  • Paralysis
  • High-temperatures
  • Disorientation
  • Vomiting
  • Stiff neck (Stiffness in the neck is often considered as a symptom for meningitis, thereby leading to a wrong diagnosis)
  • Swelling in the testicles
  • Emotional disbalance and
  • Weakness among others

Tick-borne Encephalitis:

Tick-borne encephalitis is a viral infection that affects the central nervous system of a human body. This is caused by the Tick-borne encephalitis virus which is classified as a member of the Flaviviridae family. This form is majorly classified into:

  • European tick-borne encephalitis
  • Siberian tick-borne encephalitis and
  • Far-eastern tick-borne encephalitis or Russian tick-borne encephalitis

Human beings are often accidental hosts for Tick-Borne Encephalitis Virus(TBEV). TBEV often chooses large animals as its host. Humans are most affected in the months that lie between April and November. The transmission of the virus occurs when raw goat milk, cow's milk or due to the consumption of unprocessed dairy products. Villages in India and a few urban towns in India have reported multiple cases of TBEV.

The incubation period for TBE is 8-14 days and in the initial stages, the patient exhibits symptoms including fever, vomiting, nausea, and muscle ache. 20-30% of these patients experience the second phase of the disease which affects the central nervous system and exhibit symptoms like headache, disorientation, symptoms of meningitis, abnormal motor functions. Few of the symptoms are temporary while a few leave a lasting effect based on the condition.

The European TBEV has a reported mortality rate of 1-2% while the Far-eastern TBEV has a predominantly higher rate of 25-30%.

Primary encephalitis

Primary encephalitis is when the virus directly affects brain cells. The infection is either concentrated at one spot or is widespread.

Secondary encephalitis

Secondary encephalitis is a condition when the immune system of a human body starts attacking the healthy cells of the brain instead of the infected cells. Secondary encephalitis is often seen in the last stages of the infection.



Causes of Encephalitis

Cause of Encephalitis

The primary cause of encephalitis is unknown. However, when in cases where the cause is known, they have been attributed to inflammation caused by a viral or bacterial infection. The major causes of Encephalitis include:

Herpes Simplex Virus

Herpes Simplex Virus causes an acute or subacute illness that causes general and focal dysfunction. In this, the infection in the brain is either caused by direct infection or through the olfactory nerve. Other Herpes based viruses like Epstein-Barr virus and the varicella virus also contribute to this condition.

Mosquito-borne Virus:

Mosquitoes are major vectors of Flaviviridae and in most cases, the transmission of the virus occurs from an animal bearing the virus to humans through mosquito bites. The occurrence of these instances is highest in the months between April and November.


Rabid encephalitis is a very common cause of this condition. In this, Rhabdoviridae is transferred to the human body from an infected animal to the human body through a bite. This effects in the rapid deterioration of the central nervous system and unattended cases often lead to death.


Infections like Rubella, Mumps, and Measles also cause secondary encephalitis. With vaccination available around the world for these diseases, the reported cases of encephalitis from these conditions have come down drastically.



Steps to prevent Encephalitis

As there are no vaccines available to prevent the onset of this condition, measures in the form of maintaining personal hygiene, preventing mosquito bites should be taken.

Maintaining personal Hygiene:

Washing hands and legs with soap before and after using the washroom should be made a habit. Children should also be educated about the importance of cleansing after using the washroom.

Tableware and cutlery should not be shared and the same should be taught to children in schools and educational institutions.
Getting yourself and your children vaccinated on time plays a major role in preventing the onset of encephalitis. If you are travelling to a destination which is rich in vegetation and animal husbandry, preventive measures should be discussed with a doctor.

Preventing mosquito bites:

Mosquitoes are major carriers of the encephalitis virus and hence preventive measures should be taken to ensure that you or your loved ones are protected from them.
Always wear full clothing and ensure that the unprotected part of the skin is layered with mosquito repellants. For babies, using mosquito repellants is not advised, hence, the use of mosquito nets is encouraged to prevent mosquito bites.
Using chemical compounds with permethrin is advised to keep mosquitoes away. When planning an outdoor trek or picnic, spray the compound on your gear, tent, and clothes as this repels mosquitoes away.
Ensure that no water logging or stagnant water sources are present around your residence, as these are the breeding grounds for mosquitoes.



Complications of Encephalitis

The complications of Encephalitis depend on the age of the patient, the severity of the condition and the time taken to treat the condition from the onset.

When treated in the initial stages, patients do not pose any threat to retain any long-term or permanent effects. When the condition becomes severe, it may lead to complications like:

  • Constant fatigue
  • lack of muscle coordination
  • Muscle aches
  • Vision impairment
  • Hearing disability
  • memory problems
  • Changes in personality
  • Speech impairments
  • Coma and death




Cause of Encephalitis

Encephalitis can be diagnosed through imaging studies, biopsies, urine and faeces tests, and by testing other secretions.

Through imaging studies:

MRI and CT scans can help identify the inflammation in the brain cells, thereby identifying the underlying cause of the symptoms. These can also be used to detect any malignant or benign tumours in the brain.

Lumbar Punctures:

Cerebrospinal Fluid (CSF) is the same protective fluid that is found in the spinal cord and the brain. The CSF is extracted by inserting a needle in the spinal region and the fluid is tested for abnormalities that could indicate an inflammation. Sometimes, it is also used to detect the presence of any viruses.

Urine Samples:

Urine samples and faecal matter can be tested for viruses or other disease-causing agents.

Brain Biopsy:

In a brain biopsy, a small portion of the brain cell is cut out and tested for confirming the condition. As this is an invasive procedure, this is only preferred when other forms of medications are not effective and the condition of the patient is deteriorating rapidly.


An Electroencephalogram (EEG) is a device used to measure the electrical impulses in the brain. In this, electrodes are placed on top of the scalp to identify the pattern in the electrical impulses sent across the brain. The brain communicates through electrical impulses and these when recorded with an EEG show up like a wave. Abnormalities in this can be used as a diagnosis to confirm Encephalitis.




Patients undergoing treatment for any form of encephalitis are advised to get ample bed rest, fluids either orally or intravenously and are strictly advised to follow the prescription of anti-inflammatory drugs like Tylenol and Corticosteroids to reduce the pain and inflammation caused by the condition.

The patient’s EEG and ECG should be monitored regularly to look for any anomalies in normal rhythm.
The patient should consistently be hydrated with fluids orally or through a saline drip. The patient must receive all the vitamins and minerals required to boost a speedy recovery.

Anti-inflammatory drugs:

Patients suffering from encephalitis suffer from headaches. This is commonly caused because of the inflammation in the brain. With Anti-inflammatory drugs, the inflammation is controlled while the patient recovers from the underlying cause/infection.

Antiviral drugs:

Antiviral drugs are an essential part of the treatment for encephalitis is the most common cause of known cases of encephalitis is due to the Flaviviridae virus transmitted through mosquito bites and tick bites. By treating the patient with an array of antiviral drugs, doctors eliminate the onset of severe encephalitis caused by Flaviviridae or herpes based viruses. The drugs used include Zovirax, Cytovene, and Foscavir.



Outlook and Prognosis

The prognosis for Encephalitis ranges from 2-4 weeks depending on the nature of the condition. The physical symptoms like fever and headache gradually or suddenly disappear in the first week of treatment and the neurological symptoms might take months to recover from. The speed of recovery depends on when the diagnosis was made, however, there have been cases which have deteriorated at a rapid pace even after being diagnosed in the early stages.

Untreated cases of Herpes Simplex encephalitis has a mortality rate of 50-75% while the treated cases are at 20%. 40% of the survivors have neurological complications which include distress in speech, motor functions, hearing impairments, epilepsy, and dysarthria.
Patients suffering from encephalitis over 60 years of age are likely to be affected the most by the condition and severe cases have observed patients slip into a coma or face certain death.



Road to Recovery and Aftercare

The road to recovery for patients suffering from encephalitis takes a few weeks to months depending on the severity of the condition and the stage at which it was treated. Patients with severe conditions will take a few months to get back to normal neural behaviour as encephalitis affects motor functions, speech, vision, and hearing abilities.
It is always recommended to consult a neuro-physician as advised by the medical team to track the progress.
Patients experiencing memory loss should be given extra care by their caregivers in the healing process. Brain cells are not like any other muscle groups that tend to strengthen when exercised regularly. These take time and following a steady and accurate course can help in the speedy recovery. It is advised to do things right in the initial attempts and keep practising those to make it an involuntary habit.

Keep the surroundings of patients suffering from encephalitis as uncluttered as possible and try to keep things at the same place to make it easier for the patients to remember.

Use labels and coloured markers to make identification of specific things easier. To follow and track schedules, use sticky notes or enter them in a calendar. It is also advised to take printed photographs of friends and family members and write their names on them to help in a speedy recovery.



Encephalitis FAQs: All your concerns addressed

Q.  What is Encephalitis?

  1. Encephalitis causes inflammation in the brain due to an infection that leads to headaches, fever, memory loss, disorientation in hearing, speech, and vision among others. The main cause of this is still unknown, but viruses and bacteria have been prominent in the known cases. Sometimes, as a result of the infection, the human body starts attacking the healthy brain cells instead of infected cells.

Q.  What is the lifecycle of encephalitis causing virus?

  1. The encephalitis virus is often carried on to humans from animals like horses and pigs through mosquitoes. The virus generally attacks large animals and feeds off the host, lays eggs and then transmits them to other healthy hosts through a vector (mosquito). In animals, the virus causes behavioural changes and sometimes leads to stillbirth.

Q.  Is encephalitis deadly?

  1. Yes, sometimes, depending on the age of the patient and the time taken to start the treatment, encephalitis could be fatal. The mortality rate for this disease is as high as 30%.

Q.  Is encephalitis a communicable disease?

  1. Encephalitis is communicable through the exchange of bodily fluids. Maintaining healthy hygiene and promoting and practising clean living can curb the chances of an encephalitis attack significantly.

Q.  What are the different forms of Encephalitis?

The major forms of encephalitis are:

  1. Autoimmune encephalitis
  2. TickBorne encephalitis
  3. Rabid encephalitis
  4. Herpes Simplex Encephalitis

Q.  Are there any food restrictions for patients recovering from this disease?

  1. Recovering patients are always advised to get plenty of vitamins and minerals that can help in a speedy recovery. However, depending on the severity of the condition and physical fitness of the patient, it is best to consult a doctor about this.

Q.  Can encephalitis be cured by itself?

  1. The severity of the inflammation will decide how long it’ll take for the encephalitis to be cured. If it’s mild encephalitis, then it’s possible that the inflammation may go away in a few days. Those who suffer from severe cases of encephalitis can take weeks or months to recover fully. In some extreme cases, encephalitis can cause permanent paralysis or even death.

Q.  What are the most common causes of encephalitis?

  1. No fixed cause has been found for encephalitis. However, two of the major contributing factors that have been found for encephalitis are infections and issues with the body’s immune system.
    • Infections - If an infection reaches the brain, it can lead to encephalitis. Most of these infections are generally common and not very severe, with encephalitis being a rarity. Encephalitis occurs in the presence of a virus such as herpes simplex viruses causing cold sores and genital herpes, varicella-zoster virus causing chickenpox and shingles, measles, mumps, and rubella viruses, and viruses spread by animals such as tick-borne encephalitis, Japanese encephalitis, and rabies. Encephalitis occurring from viruses are known as viral encephalitis, although it can occur from bacteria, fungi, and parasites as well.
    • Immune system issues - Generally, when germs enter the immune system, they prevent the ability to protect the body from infection. However, in rare cases, when the immune system malfunctions and attacks the brain, encephalitis may occur. This can occur when there’s a previous infection in the body, a non-cancerous or cancerous growth, and a vaccination.

Q.  How can encephalitis be diagnosed?

  1. There are several ways to detect the symptoms of encephalitis:
    • Brain Scans - You can do either a CT scan or an MRI scan to find out whether you’ve encephalitis or any other disease such as meningitis.
    • Lumbar Puncture - In this case, some fluid can be removed from the spinal cord to check for signs of encephalitis.
    • Electroencephalogram (EEG) - In this case, electrodes placed on your scalp will try to look for any abnormal brain activity.
    • Blood tests, urine tests, or tests for other bodily fluids.

Q.  Who can be affected by encephalitis?

  1. The people who are at a greater risk of encephalitis are:
    • Senior adults
    • Children below 1 year of age
    • People who have weak immune systems
    Encephalitis can also affect people who reside in areas infested with mosquitos or ticks since they are the common carriers of the disease. The chances to contract the disease is more in summer as these insects are most active then. In some cases, the MMR (measles, mumps, and rubella) vaccine has also been known to cause encephalitis.

Q.  Is there any difference between encephalitis and meningitis?

  1. Encephalitis refers to an infection that affects the brain and the spinal cord, triggering the immune system and causing an infection. This can cause a wide range of symptoms such as fever, headache, seizures, and behavioural changes.
    Meningitis, on the other hand, affects the membranes around the brain and the spinal cord, causing inflammation.

Q.  What are the symptoms of encephalitis?

  1. Generally, the meningitis symptoms start from mild and go severe over a course of hours or days. Some of the early symptoms of meningitis can be a high temperature, a headache, uneasiness, and painful joints and muscles. The serious symptoms can be disorientation, drowsiness, seizures, speaking difficulties, weakness, involuntary eye movements, hallucinations, and unconsciousness.

Q.  How can encephalitis be treated?

  1. Encephalitis, generally, requires immediate treatment and is carried out in ICUs. Some of the common treatment options once the cause is determined are:
    • Antiviral medicines
    • Steroid injections
    • Immunoglobulin therapy
    • Plasmapheresis
    • Surgery for removing tumors
    • Antibiotics or antifungal medicines