About ten percent of all encephalitis cases are caused by herpes simplex virus.
Epidemic encephalitis is part of an outbreak, such as the polio virus (Longe 2006; Chamberlin and Narins 2005).
Inflammation is usually indicated by using the English suffix "-itis," such as appendicitis, laryngitis, pancreatitis, hepatitis, and encephalitis for inflammation of the appendix, larynx, pancreas, liver, and brain, respectively.
Arthropod-borne viral encephalitis, where the viruses live in mosquitoes and animal hosts that transmit the disease, is responsible for most epidemic viral encephalitis (Longe 2006).
Japanese encephalitis and St. Louis encephalitis are also carried by mosquitoes, whereas Lyme disease and Colorado tick fever are carried by ticks.
Equine encephalitis is carried by mosquitoes, but ones that normally transmit the disease to horses and birds, which may be picked up by other mosquitoes that do bite humans (Longe 2006).
Bleeding is also uncommon except in patients with herpes simplex type one encephalitis.
Japanese encephalitis is found in much of Asia (Longe 2006).
Many cases of encephalitis are preventable, stressing the role of personal and social responsibility.
Vaccines are also available for some viruses, such as polio, herpes B, equine encephalitis, and Japanese encephalitis, as well as rabies for animals (Chamberlin and Narins 2005).
Primary encephalitis occurs when the virus directly infects the brain.
Herpes simplex encephalitis, if untreated, has a mortality rate between 60 and 80 percent; if treated, that number drops to 15 to 20 percent.
Certain parasitic protozoal infestations, like by toxoplasma or Naegleria fowleri, also can cause encephalitis in people with compromised immune systems.
acyclovir for herpes encephalitis) and are used with limited success for most infection except herpes simplex encephalitis.
Encephalitis lethargica is an atypical form of encephalitis which caused an epidemic from 1917 to 1928.
Encephalitis results in the brain's tissues becoming swollen, which can lead to a headache or fever, or even more severe symptoms (Longe 2006).
The symptoms of encephalitis are caused by the brain's defense mechanisms activating to get rid of the infection.
Adult patients with encephalitis present with acute onset of fever, headache, confusion, and sometimes seizures.
Patients with encephalitis suffer from fever, headache and photophobia, with weakness and seizures also common.
Encephalitis often is accompanied by an inflammation of the brain's covering (the meninges), a condition called meningitis.
Encephalitis may also occur in response to vaccination against a viral disease or by infection by prions, a type of infectious agent made only of protein, lacking the nucleic acids that are part of viruses.
Cerebral abscess is more common in patients with meningitis than encephalitis.