Herpes zoster

An infection of the nerves supplying certain skin areas that is characterized by a painful rash. Also called shingles, herpes zoster is especially common among older people. It often affects 1 side of the body only. Sometimes the infection involves the face and eye and is called herpes zoster ophthalmicus. Herpes zoster is caused by the varicella–zoster virus, which also causes chickenpox. After an attack of chickenpox, some of the viruses survive and lie dormant for many years. In some people, a decline in the efficiency of the immune system, especially in old age or because of disease, allows the viruses to re-emerge and cause herpes zoster. Herpes zoster is also common in people whose immune system is weakened by stress or by certain drugs, such as corticosteroid drugs or anticancer drugs. The first indication of herpes zoster is excessive sensitivity in the skin, followed by pain. After about 5 days, the rash appears as small, raised, red spots that soon turn into blisters. These dry and develop crusts that drop off, sometimes leaving small pitted scars. The most serious feature of herpes zoster is pain after the attack (postherpetic pain), caused by nerve damage, which may last for months or years. Herpes zoster ophthalmicus may cause a corneal ulcer or uveitis. If treatment is begun soon after the rash appears, antiviral drugs, such as aciclovir, will reduce the severity of the symptoms and minimize nerve damage. Analgesic drugs may also be helpful.