Friday , 24 May 2024

Encephalitis- Types, Symptoms, Causes, Risk Factors, Diagnosis, Treatment

What is Encephalitis

Encephalitis is a condition that causes acute inflammation of the brain. In the majority of the cases, it is either a viral infection or immune system mistakenly attacking brain tissue and causing inflammation of the brain.

They are more than 18,000 hospitalizations because of encephalitis reported every year. About 15 per cent of encephalitis cases occurs in HIV-infected patients.


Encephalitis usually begins with symptoms like fever and headache. After the initial stage, the symptoms get worse causing seizures, drowsiness, confusion and loss of consciousness and sometimes even coma.

This condition can become life-threatening, but this occurs rarely. Mortality of the individual depends on several factors which include the severity of the disease and age. Younger patients recover soon without any health issues, while elderly patients might suffer from complications and mortality.

Types of Encephalitis

The following are the different types of Encephalitis which occurs due to different causes:

  • Japanese Encephalitis: it is spread by mosquitoes
  • Tick-borne encephalitis: It is spread by ticks
  • Rabies: It is spread through a bite and mammal acts as carriers.

Encephalitis is further divided into primary and secondary Encephalitis

Primary Encephalitis:

It is also called infectious Encephalitis. This typically occurs if a fungus, virus, or bacterium infects the brain.

Secondary Encephalitis:

This type is post-infectious where immune system responds to a previous infection and mistakenly attacks the brain.

Symptoms of Encephalitis

The symptoms of Encephalitis are as follows:

  • Fever
  • Headache
  • Photophobia (sensitivity to light)
  • General weakness
  • Seizures

Less common symptoms

The patient experience the following symptoms less commonly

  • Nuchal rigidity i.e., neck stiffness
  • Stiffness of limbs
  • Slow movements
  • Clumsiness
  • The patient may also feel drowsiness and coughing

Serious Symptoms

  • Very severe headaches
  • Nausea, vomiting
  • Confusion, disorientation
  • Memory loss, speech problems
  • Hearing problems
  • Hallucinations, seizures and sometimes coma
  • In some cases, the patient becomes more aggressive.

Causes of Encephalitis

The exact cause of Encephalitis is not known. A viral infection is the most common known cause of it. Bacterial infection and noninfectious inflammatory are also known causes of encephalitis.

As discussed earlier, two main types of Encephalitis causes Encephalitis:

Primary Encephalitis:-

This type occurs when a virus or any other agent directly infects the brain. The infection is confined to one part of the brain or may spread to other areas as well.

Secondary Encephalitis:-

this condition occurs as a result of the faulty immune system which reacts to the infection and also healthy cells. Instead of targeting infection-causing cells immune system mistakenly attacks healthy cells in the brain. This type usually occurs after two to three weeks of initial infection.

Other Viral Causes:

  • Herpes simplex virus
  • Enterovirus
  • Mosquito-borne viruses
  • Tick-borne viruses
  • Rabies Virus
  • Childhood infections

Risk Factors of Encephalitis

  • People of all ages are at risk of getting Encephalitis but the factors which can increase the risk are as follows:-
  • Geographic region:- The regions where mosquito- or tick-borne diseases are common.
  • Season:- During the rainy season where mosquito-borne disease and tick-borne disease are likely to occur.
  • Weak Immune system:- People who suffer from HIV/AIDS causes a weakened immune system are at increased risk of encephalitis.
  • Age:- Some people like young children and elderly people are at greater risk of getting viral Encephalitis.


Your health care professional may start with a thorough physical examination and medical history. The following are the tests which are recommended by the doctor:

MRI or CT scan:-

Brain imaging is done to know any swelling of the brain or any other condition that might be causing tumours like symptoms.

Spinal Tap:-

This procedure is also called a lumbar puncture. In this procedure, a needle inserted into the lower back and cerebrospinal fluid are taken out. This fluid indicates inflammation or infection in the brain.

Electroencephalogram (EEG):-

Electrodes are fixed to your scalp and brain’s electrical activity is recorded. Abnormal patterns indicate which may help in the diagnosis of Encephalitis.

Brain biopsy:-

This procedure is done when the condition of the brain is worsened and the disease doesn’t respond to the treatments.

Lab tests:-

other lab tests like blood, urine samples are collected to know viruses or other infections.


Mild Encephalitis:-

Treatment for mild Encephalitis includes bed rest, lots of fluids, anti-inflammatory drugs which includes NSAIDs such as acetaminophen, ibuprofen, and naproxen- helps to relieve headaches and fever.

Viral Encephalitis:-

Certain antiviral medications are used to treat viral Encephalitis which include: Acyclovir, Ganciclovir, Foscarnet. Antiviral drugs are well tolerated and side effects are rarely seen.

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