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Viral encephalitis is a rare condition that is characterized by inflammation of the brain. It may be caused by a herpes virus, such as the herpes simplex virus (HSV), or an arbovirus, that is transmitted by blood-sucking insects, such as mosquitoes. Less commonly, brain inflammation may also be caused by other viruses such as adenoviruses, enteroviruses, rabies, and those associated with childhood diseases such as mumps, measles, and rubella.

Viral encephalitis can affect anyone, but in most cases, young children and elderly individuals are involved. It is estimated that about three to seven per 100,000 individuals are affected yearly in the US. Other factors that may increase one's risk of acquiring the disease include weakened immune system (especially in people with HIV/AIDS or using immunosuppressive drugs), seasonal and environmental factors.

Symptoms of Viral Encephalitis

In most cases, patients experience mild flu-like symptoms that include fever, headache, weakness and body aches. However, more serious conditions may include the following symptoms:

  • Seizures
  • Confusion and agitation
  • Hallucinations
  • Loss of sensation
  • Muscle weakness
  • Problems with speech or hearing
  • Perception of foul smell
  • Paralysis in certain areas of the body or face
  • Double vision
  • Loss of consciousness

Infants and young children may exhibit the following signs:

  • Bulging of fontanels (soft spot in the skull)
  • Nausea, vomiting
  • Stiffness of the body
  • Poor feeding
  • Irritability
  • Inconsolable crying

Complications of Encephalitis

The prognosis of patients depends on the cause of the disease, treatment, and the patient's immune status.

Most people who suffer from mild cases of encephalitis fully recover within two to four weeks.

Seventy per cent of patients who have severe viral encephalitis caused by HSV, if left untreated, may die, and those who survive may have long-lasting complications.

Infants under 12 months of age and adults over 55 years have the worst outcomes.

Brain swelling may cause depression of respiratory and cardiac functions, which may lead to coma and death.

Survivors of viral encephalitis may experience neurologic consequences, or complications from brain damage, which can be long lasting or permanent. The type of brain damage involved depends on the part of the brain involved, and severity may range from mild to severe. If only one part of the brain is affected, focal damage occurs, resulting in specific changes, such as loss of muscle control or seizures. If several parts of the brain are affected, multifocal damage occurs, which may lead to varying changes in memory, perception, speech, behavior, and physical control. A diffuse damage involves the whole brain and may lead to coma. Some patients awaken from coma with mild complications, but others may die or develop severe complications such as mental retardation. A number of patients also develop recurrent unprovoked seizures within years of infection.

To prevent complications or death from viral encephalitis, it is important to get early diagnosis and treatment. Young children who exhibit signs and symptoms of viral encephalitis should be brought to the doctor immediately. Anyone who is experiencing symptoms associated with severe viral encephalitis, such as fever, severe headache, and altered consciousness must receive urgent care.

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