herpes zoster
This is an infection that is caused by the varicella-zoster virus. This is the same virus that causes chickenpox. In most cases, once a person recovers from chickenpox, the virus remains inactive in his or her body. But in some people, the virus becomes active again later in life. When this happens, the virus travels down nerve fibers and can infect any part of the body. The infection causes a blistering rash (called shingles), fever, painful inflammations of the affected nerve fibers, and a general feeling of sluggishness. In many people who have a varicella-zoster infection in their head or neck, the virus also affects the cornea.