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What is encephalitis?

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Encephalitis is a rare, severe inflammatory disease in the parenchyma of the brain, usually caused by a viral infection. It occurs most often in the first year of life and less often as age advances. It is most often accompanied by inflammation of the meninges (meningoencephalitis) or spinal cord (encephalomyelitis, meningoencephalomyelitis). This is a potentially life-threatening condition, so immediate medical intervention is required.

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How is it caused?

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There are two types of encephalitis: primary and secondary.

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Primary encephalitis is more serious and occurs when a microorganism directly infects the brain or spinal cord.
Secondary encephalitis is milder and is caused when the infection starts elsewhere in the body and then infects the brain.

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Secondary encephalitis may be the result of the immune system overreacting to a foreign substance. Usually, it occurs after a viral infection, such as measles, chickenpox, rubella or mumps.

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What are the causes?

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The most common causes of encephalitis are:

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Infection

Viruses (e.g. herpes, arboviruses, Coxsackie, HIV, cytomegalovirus, rubella, mumps)
Bacteria (e.g. staphylococcus aureus)
Parasites-Protozoa (e.g. toxoplasma)
Fungi (e.g. candida, aspergillus, cryptococcus)

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Other causes:

Allergic reaction to vaccinations
Autoimmune diseases
Complications of cancer

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In most cases, encephalitis is viral, with herpes simplex virus being the most common. Encephalitis from parasites or fungi almost always affects immunocompromised individuals.

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What are the risk factors?

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Anyone can develop encephalitis. But the factors that increase the risk are:

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Age: most common in young children and the elderly
Weakened immune system
Geographical locations endemic for encephalitis viruses
Season: most often in spring, summer and early autumn

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What are the symptoms?

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Most people with viral encephalitis have no symptoms or show symptoms similar to those of influenza, such as:

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Mild headache
Fever
Muscular weakness
Fatigue
Vomit
Rigidity of the neck

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In more severe cases of encephalitis, signs and symptoms may include:

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Fever above 39.4ᵒC

Muscular weakness
Paralysis
Behavioural/personality changes
Irritability
Confusion or hallucinations
Blurred vision or double vision
Sensitivity to light
Epileptic seizures
Speech disorder
Hearing problems
Loss of consciousness
Comma

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Infants and young children usually have different symptoms. These are:

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Vomiting
View of fetal skull sources (soft spots on the skull)
Constant crying
Rigidity of the body
Reduced appetite

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The onset of neurological symptoms may occur after one to seven days from the initial symptoms. In the case of secondary viral encephalitis, the disease may develop in 7 to 30 days after the onset of the initial infection.

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What is the outcome of the disease?

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The outcome will depend on the severity of the inflammation. In mild cases, the inflammation subsides within a few days. For severe cases, it may take weeks or months of recovery. Sometimes permanent damage and even death can result. Serious damage can include:

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Paralysis
Loss of brain function
Problems with speech, behaviour or memory
Hearing and vision disorders
Balance disorders

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How is the diagnosis made?

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A patient with suspected encephalitis undergoes a series of tests. In particular:

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Magnetic resonance imaging (MRI) or computed tomography (CT)
Cerebrospinal fluid analysis by lumbar puncture
Electroencephalogram
Blood tests
Brain biopsy - when the results are negative but the symptoms warrant it

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What is the treatment?

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Encephalitis is treated in hospital under close observation and appropriate treatment. Treatment focuses on relieving symptoms and reducing complications. Treatment includes:

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