Eastern equine encephalitis occurs in eastern and southeastern United States; western equine and California encephalitis occur throughout the West; and St. Louis encephalitis occurs throughout the country.
Because of the rarity of Reye's syndrome, it is often misdiagnosed as encephalitis, meningitis, diabetes, or poisoning, and the true incidence may be higher than the number of reported cases indicates.
Although only one in 1,000 patients with measles will develop encephalitis, 10 to 15 percent of those who do will die, and about another 25 percent will be left with permanent brain damage.
An infection of the membrane covering the brain (meningitis) or an inflammation of the brain itself (encephalitis) cause swelling that in turn may cause brain damage and mental retardation.
A brain biopsy (surgical gathering of a small tissue sample) may be recommended in some cases in which treatment has thus far been ineffective and the cause of the encephalitis is unclear.
These illnesses include pneumonia and inflammations of the liver (hepatitis), brain (encephalitis), esophagus (esophagitis), large intestine (colitis), and retina of the eye (retinitis).
In secondary encephalitis, symptoms usually begin five to ten days after the onset of the disease itself and are related to the breakdown of the myelin sheath that covers nerve fibers.
Primary encephalitis is caused by direct infection by the virus, while secondary encephalitis is due to a post-infectious immune reaction to viral infection elsewhere in the body.
Using the term "narcolepsy" to mean all disorders that caused daytime sleepiness, this included illnesses that were not actually sleep disorders such as lethargic encephalitis.
An increase in WBCs may occur in many conditions, including infection (viral, bacterial, fungal, and parasitic), allergy, leukemia, hemorrhage, traumatic tap, encephalitis, and Guillain-Barré syndrome.