April 2003, Volume 33 Number 4 , p 70 - 71
Outline Identifying signs and symptoms
Identifying common viral culprits
SELECTED WEB SITES
CHARACTERIZED BY swelling of brain tissue and surrounding meninges, encephalitis is usually triggered by a viral infection (see Identifying Common Viral Culprits ). Less-common causes include bacterial, fungal, and parasitic infections; cancer; and exposure to toxins or drugs.
The severity of encephalitis depends on the underlying cause, the patient's age and condition, and the duration of illness before treatment. People who are immunocompromised are especially vulnerable.
Primary encephalitis indicates that a pathogen or toxin has directly attacked the brain and spinal cord. Herpes simplex and mosquito-borne viruses are most likely to trigger primary encephalitis. Secondary encephalitis is caused by an infection in another part of the body or by the body's immune response ...