Herpes simplex viruses include types 1 and 2. Both are enveloped, double-stranded DNA
viruses with a linear DNA structure
. Type 1 is spread through respiratory secretions and saliva, and is the most common cause of sporadic encephalitis. It also causes gingivostomatitis, keratoconjunctivitis, herpes labialis
, herpetic whitlow, and temporal lobe encephalitis. Type 2 is transmitted through sexual contact and perinatally, and causes meningitis
, herpes genitalis
, and neonatal herpes. It can lie dormant in the sacral ganglia. Treatment for both types is acyclovir
. Foscarnet is used second-line. These drugs do not destroy latent forms of virus.