Encephalitis Explained: What Causes This Condition?

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Causes of Encephalitis

Encephalitis is a condition that is characterized by inflammation of the brain. The most common cause of this condition is viral infections.

Encephalitis can manifest itself with flu-like symptoms such as a headache and/or fever. In addition, it can result in seizures, complications with movement and/or senses, and confusion. However, in most cases, this condition only manifests with mild flu-like symptoms or none at all.

While severe cases of this condition are fairly rare- they can be extremely life-threatening. Since the course of encephalitis is often unpredictable, it is critical that you receive diagnosis and treatment as soon as possible.

Causes of Encephalitis

Most medical experts agree that the exact cause of this condition is unknown. However, the most common diagnosis is a viral infection. Still, noninfectious inflammatory conditions and bacterial infections can also lead to encephalitis.

Infections can result in one of two conditions that affect the brain:

Primary Encephalitis: this condition occurs when a particular virus our infectious agent infects the brain directly.

This infection will either be widespread throughout the brain or concentrated in one particular area. Primary infections might be a reactivation of a virus that has been latent after experiencing a previous illness.

Secondary Encephalitis: this is also referred to as Postinfectious Encephalitis and is due to an improper immune response to an infection located somewhere else in the body.

Instead of only attacking the cells that have caused the infection, the immune system also attacks the healthy brain cells.

The condition of secondary encephalitis will often occur 2-3 weeks following an infection. In rare cases, this condition can occur due to a complication of a vaccine that uses a live virus.

Common Viral Causes of Encephalitis

Some of the most common viral causes of encephalitis include the following:

Herpes Simplex Virus: you probably already know that there are two forms of the herpes simplex virus, or HSV. Either form can lead to the condition of encephalitis.

HSV- 1 is what typically causes fever blisters or cold sores around your mouth. HSV- 2 is the virus that causes genital herpes. While it is rare that HSV- 1 causes encephalitis, it can happen and could possibly lead to brain damage and even death.

Other Herpes Viruses: there are some other herpes viruses that can lead to the condition of encephalitis, including: Epstein-Barr (which is the cause of infectious mononucleosis), and varicella-zoster (which is the cause of shingles and chickenpox).

Enteroviruses: this form of viruses includes coxsackievirus (which typically results in an illness that is characterized by abdominal pain, inflammation of the eyes and flu-like symptoms) and poliovirus.

Mosquito-transmitted viruses: these are known as arboviruses and are transmitted through the bite of a mosquito or other blood-sucking insect.

Mosquito-transmitted viruses include: La Crosse, Western Equine Encephalitis, Eastern Equine Encephalitis, St. Louis, and West Nile Virus.

These viruses are transferred when a mosquito bites an animal and then bites a human. The symptoms of an infection will typically manifest within a few days to a few weeks after being exposed.

Tick-transmitted viruses: one of the most well-known tick-transmitted viruses is the Powassan virus. This virus often leads to the condition of encephalitis and will typically manifest with a week of exposure.

Rabies virus: while rabies is a rare cause of the condition of encephalitis in the United States, it can happen and is caused when an infected animal bites a human.

Childhood infections: while these are now rare causes due to the availability of vaccines, infections such as measles, mumps, and rubella used to be very common causes of the condition of secondary encephalitis, especially in children.

Risk Factors for Encephalitis

Keep in mind that absolutely anyone can develop this condition. However, there are some risk factors that can increase your risk for developing it, including the following:

Age: there are some types of encephalitis that are more common and/or severe in specific age groups.

Generally, very young children and much older adults are at an increased risk for developing most forms of viral encephalitis.

However, in individuals 20-40 years old, encephalitis caused by the herpes simplex virus is much more common.

Weakened Immune System: individuals who have conditions such as HIV/AIDS, are taking medications that suppress their immune system, or are suffering from another condition that causes a weakened or compromised immune system, are at a much greater risk for developing this condition.

Geographical Regions: in some geographical regions, the tick-transmitted and mosquito-transmitted viruses are much more common.

Seasons of the year: in most areas of the United States, the tick-transmitted and mosquito-transmitted viruses are more prevalent during the spring through early fall. However, in some of the warmer areas of the Unite States, these pests may be present all year round.

Complications of Encephalitis

The complications that can result from the condition of encephalitis are heavily dependent upon several different factors including: the severity of the initial illness, age, and the cause of the infection- as well as the time between when the condition started to the time that it was treated. In most cases, individuals who experience a mild illness can expect to recover within a few weeks with no complications.

On the other hand, for those who have severe illnesses, keep in mind that injury to your brain caused by inflammation can lead to a variety of problems- the most severe being coma or even death. Some of the other complications vary in severity, but may last for several months or even be permanent:

  • Changes in personality
  • Paralysis
  • Persistent fatigue
  • Lack of muscle coordination/weakness
  • Defects in vision and/or hearing
  • Problems with memory
  • Impairments in speech

Treatments for Encephalitis

Many times, mild cases of encephalitis are mistaken as the flu, and treatment consists of the following:

  • Plenty of fluids (to avoid becoming dehydrated)
  • Lots of rest
  • Anti-inflammatory medications to relive fever and/or headaches

On the other hand, if the encephalitis is caused by specific viruses, IV antiviral treatments will be required. Some of the side effects of these antiviral medications include: diarrhea, vomiting, pain, joint/muscle soreness, and nausea. In addition, some of the rare but serious side effects include abnormalities in liver and kidney function and even suppression of activity of bone marrow. The proper tests will be employed to check for these more serious side effects.

In addition to the above, supportive care is also often required for those individuals who have been hospitalized with severe cases of encephalitis. This supportive care includes the following:

  • Assistance with breathing
  • Anti-inflammatory medications
  • Intravenous fluids
  • Anticonvulsant medications

Finally, after initial treatment, it may be a good idea to receive additional medical help, depending upon the severity and type of complications you experience. This can include the following:

  • Physical therapy
  • Psychotherapy
  • Speech therapy
  • Occupational therapy