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Posted by on May 29, 2015 in blog, Neurosciences | 0 comments

Encephalitis

Encephalitis

 

Unlike meningitis, which is an inflammation of the layers covering the brain, encephalitis is an acute infection and inflammation of the brain itself and is generally a viral illness.

Encephalitis can also be caused by viruses such as those responsible for cold sores mumps, measles, and chickenpox. Insects such as mosquitoes and ticks spread a certain family of viruses, the arboviruses. The equine (meaning horse), West Nile, Japanese, La Crosse, and St. Louis encephalitis viruses are all spread by mosquitoes.

Although viruses are the most common source of infection, bacteria, fungi, and parasites can also be responsible.

The illness is similar to the flu and lasts for two to three weeks. It can vary from mild to life threatening, even causing death. Most people diagnosed with mild illness can recover fully. However, more severe cases may have some permanent damage to their nervous system.

  •  Age, season, geographic location, regional climate conditions, and strength of the person’s immune system can influence th development of the disease and severity of the illness.
  • Herpes simplex (the virus causing cold sores) remains the most common virus involved in encephalitis.
  • In the U.S., there are five main viruses spread by mosquitoes: West Nile, Eastern equine encephalitis (EEE), Western equine encephalitis (WEE), La Crosse, and St. Louis encephalitis.
  • Venezuelan equine encephalitis has been traced to South America. The infection is very mild and nervous system damage is rare.
  • Japanese encephalitis virus is the most common arbovirus in the world (virus transmitted by blood-sucking mosquitoes or ticks) and is responsible for 50,000 cases and 15,000 deaths per year. Most of China, Southeast Asia, and the Indian subcontinent are affected by this virus.

Symptoms of encephalitis
The signs and symptoms of encephalitis are the same for adults and children. They may last for two to three weeks, are flu-like, an can include one or more of the following:

  • Fever
  • Fatigue
  • Sore throat
  • Stiff neck and back
  • Vomiting
  • Headache
  • Confusion
  • Irritability
  • Unsteady gait
  • Drowsiness
  • Visual sensitivity to light

More severe cases of encephalitis may involve these signs and symptoms:

  • Seizures
  • Muscle weakness
  • Paralysis
  • Memory loss
  • Sudden impaired judgment
  • Poor responsiveness

When to seek medical care for encephalitis
If you develop signs and symptoms of encephalitis, seek a doctor’s advice immediately. Also look for the following
conditions:

  • You have sores around the lips or genitals, through contact with another person
  • You were in a forest area and suspect mosquito bites
  • You visited an area where these diseases are common
  • You were bitten by a tick

Exams and tests for encephalitis
Geographic location and seasonal occurrence can help identify the specific cause of encephalitis. The doctor may perform one or more of the following tests depending on your condition:

  • CT scan or magnetic resonance imagining (MRI) scan.
  • Polymerase chain reaction (PCR), a DNA study, helps diagnose herpes encephalitis.
  • A reading of the electrical activity of the brain with an EEG can detect irregularities. Herpes encephalitis produces a characteristic EEG pattern.
  • A lumbar puncture, also known as a spinal tap, may be necessary to isolate the virus. During this procedure, the doctor applies local numbing medication and then inserts a needle into your lower back to collect fluid from the space around the spinal column for analysis.
  • The virus may also be isolated from tissue or blood.
  • Brain biopsy is an option although it is rarely done and usually if the other tests are inconclusive.

Encephalitis treatment and care at home
Considering encephalitis can be fatal, it is better to be hospitalised. Any home treatment to relieve the flu-like symptoms should be carried out only after consulting a doctor post diagnosis.

Medical treatment for encephalitis
Encephalitis is a viral illness for which antibiotics are not used for treatment. However, Japanese encephalitis is the
only illness that can be prevented by vaccination.

  • Except herpes encephalitis, the mainstay of treatment is symptom relief. People diagnosed with encephalitis are kept hydrated wit IV fluids while the brain is monitored for any swelling. Anticonvulsants can be given for seizure control. Steroids have not proved to be helpful.
  • If not diagnosed and treated promptly, Herpes encephalitis can cause rapid death. Hence, as soon as the doctor suspects herpes, h starts medication without waiting for the confirmatory results. Acyclovir (Zovirax) is given by IV for two to three weeks. Acyclovir resistant herpes encephalitis can be treated with foscarnet (Foscavir). During the course of treatment liver and kidney functions are monitored.
  •  The use of ribavirin (Rebetol, Virazole) in the treatment of a child with La Crosse encephalitis is being studied.

Follow-up for encephalitis

The initial treatment for encephalitis must involve regular follow up with doctor, as certain nervous system problems are likely to develop. Relapse can occur with herpes encephalitis.

Prevention of encephalitis
To prevent encephalitis, follow these suggestions:

  • Do not ignore high fever.
  • If you are visiting a forest area, it’s advisable to be fully clothed to avoid ticks and mosquitoes.
  • Use insect repellant on exposed areas of the body.
  • Do not spend too much time outdoors during dusk or early morning when insects tend to bite.
  • Vaccinate children against viruses that can cause encephalitis.

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