<unk>  is a severe viral infection of the central nervous system.<unk>  may be classified according to the origin of the disease into two subtypes: oral (HSV-1) and genital (HSV-2). The exact pathogenesis of<unk>  is not fully understood.<unk>  must be differentiated from other diseases that cause fever, headache, and altered mental status. Physical examination findings for<unk>  are generally unspecific.<unk>  constitutes a medical emergency. If left untreated, approximately 70% patients with<unk>  progress to mortality. Common complications of<unk>  include meningitis, increased intracranial pressure, and coma. Laboratory findings consistent with the diagnosis of<unk>  include increased leukocytes in cerebrospinal fluid. Polymerase chain reaction is critical in the diagnosis of<unk> , as there is a 95-98% specificity and sensitivity beginning as early as one day after symptoms first appear and lasting up to one week after treatment. Magnetic resonance imaging is the imaging modality of choice for<unk> . The mainstay of therapy for<unk>  includes antiviral therapy. The drug of choice is acyclovir.
Herpes simplex encephalitis
Varicella zoster encephalitis
Japanese encephalitis
Eastern equine encephalitis
La Crosse encephalitis
Tick-borne encephalitis
Western equine encephalitis
St. Louis encephalitis