What is Encephalitis?

Encephalitis is a type of acute brain inflammation. A viral infection or the immune system wrongly targeting brain tissue are the most common causes. 

Encephalitis is responsible for an estimated 19,000 hospitalizations, 230,000 hospital days, and $650 million in hospitalization costs in the United States, according to Trusted Source.

The HIV-infected population accounts for about 15% of encephalitis cases. The symptoms, causes, treatments, and complications of encephalitis will be discussed in this article.

Fast facts on encephalitis

Here are some key points about encephalitis. More details and supporting information are in the main article.

  • Fever, photophobia, and headaches are the first signs.
  • Encephalitis is a type of encephalitis that is rarely fatal.
  • Children, the elderly, and individuals with weakened immune systems are the most common victims of encephalitis.
  • Only a few antiviral drugs can aid with encephalitis treatment.
  • Epilepsy and memory loss are two possible encephalitis complications.

What is encephalitis?

Encephalitis is an acute inflammation (swelling) of the brain, usually resulting from either a viral infection or due to the body’s own immune system mistakenly attacking brain tissue.

In medicine, “acute” means it comes on abruptly and develops rapidly; it usually requires urgent care.

The most common cause is a viral infection. The brain becomes inflamed as a result of the body’s attempt to fight off the virus.

Encephalitis occurs in 1 in every 1,000 cases of measles.

Encephalitis generally begins with a fever and headache. The symptoms rapidly worsen, and there may be seizures (fits), confusion, drowsiness, loss of consciousness, and even coma.

Encephalitis can be life-threatening, but this is rare. Mortality depends on a number of factors, including the severity of the disease and age.

Younger patients tend to recover without any ongoing health issues, whereas older patients are at higher risk for complications and mortality.

When there is direct viral infection of the brain or spinal cord, it is called “primary encephalitis.” Secondary encephalitis refers to an infection that started off elsewhere in the body and then spreads to the brain.


Different types of encephalitis have different causes.

  • Japanese encephalitis is spread by mosquitoes.
  • Tick-borne encephalitis is spread by ticks.
  • Rabies can be spread through a bite from a mammal.

There is also primary or secondary encephalitis.

Primary or infectious encephalitis can result if a fungus, virus, or bacterium infects the brain.

Secondary, or post-infectious, encephalitis is when the immune system responds to a previous infection and mistakenly attacks the brain.


The patient typically has a fever, headache, and photophobia (excessive sensitivity to light). There may also be general weakness and seizures.

Less common symptoms

The individual may also experience nuchal rigidity (neck stiffness), which can lead to a misdiagnosis of meningitis. There may be stiffness in the limbs, slow movements, and clumsiness. The patient may also be drowsy and have a cough.

More serious cases

In more serious cases, the person may experience very severe headaches, nausea, vomiting, confusion, disorientation, memory loss, speech problems, hearing problems, hallucinations, as well as seizures and possibly coma. In some cases, the patient can become aggressive.

Infant signs and symptoms

Initially, encephalitis is harder to detect in young children and babies. Parents or guardians should look out for vomiting, a bulging fontanel (the soft area on the top center of the head), incessant crying that does not get better when the baby is picked up and comforted, and body stiffness.


Encephalitis can develop as a result of direct infection of the brain by a virus, bacterium, or fungus, or when the immune system responds to a previous infection; the immune system mistakenly attacks brain tissue.

Primary (infectious) encephalitis can be split into three main categories of viruses:

  1. HSV (herpes simplex virus) and EBV (ebola virus) are two common viruses (Epstein-Barr virus)
  2. Viruses that affect children, such as measles and mumps
  3. Arboviruses, such as Japanese encephalitis, West Nile encephalitis, and tick-borne encephalitis, are spread by mosquitoes, ticks, and other insects.

Secondary encephalitis: could be caused by a complication of a viral infection. Symptoms start to appear days or even weeks after the initial infection. The patient’s immune system treats healthy brain cells as foreign organisms and attacks them. We still do not know why the immune system malfunctions in this way.

In more than 50 percent of encephalitis cases, the exact cause of the illness is not tracked down.

Encephalitis is more likely to affect children, older adults, individuals with weakened immune systems, and people who live in areas where mosquitoes and ticks that spread specific viruses are common.


The goal of encephalitis treatment is to reduce symptoms. There are just a few particular antiviral medications that have been reliably tested to help, one of which being acyclovir; effectiveness is limited for most infections, except when the infection is caused by herpes simplex.

Corticosteroids may be used to treat inflammation in the brain, particularly in cases of post-infectious (secondary) encephalitis. If the patient’s symptoms are severe, they may require mechanical ventilation as well as additional supportive care.

Patients with seizures are sometimes given anticonvulsants. Sedatives can help with seizures, agitation, and restlessness.

Rest, plenty of fluids and Tylenol (paracetamol) for fever and headaches are the recommended treatments for people with mild symptoms. Tylenol can be ordered via the internet.


Doctors who identify the classic symptoms in adults—fever, headache, confusion, and occasionally seizures, or irritability, poor appetite, and fever in young children—may order further diagnostic tests.

A neurological examination generally finds that the patient is confused and drowsy.

The doctor may suspect meningitis or meningoencephalitis if the neck is stiff due to inflammation of the meninges (membranes that surround the brain and spinal cord).

A lumbar puncture, which extracts a sample of cerebrospinal fluid from the spine, could reveal higher-than-normal protein and white blood cell levels.

However, this test is not always decisive; in certain circumstances, even if the patient has encephalitis, the results may come back normal.

A CT scan can help detect structural changes in the brain. Other causes, such as strokes, aneurysms, or tumors, can also be ruled out. However, for encephalitis, an MRI is the best imaging choice since it can detect the characteristic brain abnormalities that indicate encephalitis.

An EEG (electroencephalograph) that monitors the electrical activity of the brain may show sharp waves in one or both of the temporal lobes in patients with encephalitis.

The doctor might order a blood test if a West Nile virus infection is thought to be the cause.


The majority of patients who have encephalitis go on to have at least one complication, especially elderly patients, those who had symptoms of coma, and individuals who did not receive treatment at an early stage.

Complications may include:

  • Loss of memory – especially among those who had herpes simplex virus encephalitis
  • Behavioral or personality changes—such as mood swings, bouts of frustration and anger, and anxiety
  • Epilepsy
  • Aphasia—language and speech problems


The most effective strategy to reduce the risk of encephalitis is to stay up to date on immunizations. Measles, mumps, rubella, and, if the virus is present in those locations, Japanese encephalitis, and tick-borne encephalitis vaccines are among them.

Individuals who live in places where mosquitoes carrying encephalitis-causing viruses are known should take precautions to avoid being bitten.

Wearing appropriate clothing, avoiding mosquito-infested areas, avoiding going outside at specific times of the day when there are large numbers of mosquitoes about, keeping the home mosquito-free, using mosquito repellent and making sure there is no stagnant water around the home are all examples of what you can do.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top