Herpes zoster (shingles) is a nerve and skin infection that occurs as a result of reactivation of latent varicella zoster virus (VZV). Approximately one million cases of shingles are diagnosed each year in the U.S. People with a history of a primary varicella infection (chickenpox) have a 10 to 20 percent lifetime chance of developing shingles. Shingles is more common in older adults as immunity to VZV declines over time, however shingles in younger persons does occur. Usually the likelihood of developing shingles begins to rise between 50 and 60 years of age. Also a family history of shingles is a risk factor. Other groups of people are at increased risk of shingles. Those groups include organ transplant recipients, people with compromised immune systems, and those with cancer or HIV/AIDS. Sometimes shingles in a younger person may be the first sign of an HIV infection.
Shingles typically appears on the upper abdomen, mid to upper back, torso, or head, which are the same areas where the rash from chickenpox occurs. Shingles involving the eye can be particularly troublesome, and if untreated, may lead to blindness. Shingles begins first with pain in the affected area. Because the red, blistery rash of shingles appears about three to four days after the onset of pain, a person with shingles may not realize that the pain is from shingles until the rash appears. Typically the rash appears on one side of the body and does not cross the midline. Because the VZV infects a spinal nerve causing an inflammation of the nerve, or neuritis, the pain can be excruciating and debilitating. A small percentage of shingles sufferers may go on to develop postherpetic neuralgia where the pain may last for many months or longer.
The reason that the VZV reactivates in the body is unknown. Many shingles sufferers do not recall having had chickenpox. The reason for that is that the VZV is extremely common. Ninety-five percent of the world’s population has been infected with VZV and about 80 percent of those born in the pre-varicella vaccine era have evidence of VZV immunity even in the absence of clinical chickenpox. Antiviral treatment with famcyclovir, valcyclovir, or acyclovir should be started as soon as possible after the appearance of the rash. Antivirals are most effective if started within 72 hours of the appearance of the rash but may be started at any time during the infection. Steroids may produce a modest effect on pain relief and healing time, but do not affect the risk of developing postherpetic neuralgia. Some medications used to treat chronic nerve pain, like gabapentin and Lyrica, may help with pain relief in shingles.
A live attenuated vaccine called Zostavax is available for adults over 60 for primary prevention against shingles and post-herpetic neuralgia. Unfortunately the vaccine is quite expensive and not all insurance plans cover it. Merck, the manufacturer of the vaccine, recommends that all persons who have had shingles should get the vaccine, but a person with a normal immune system who gets shingles will develop the immunity on their own, although it probably wouldn’t hurt to get the vaccine after a bout of shingles. At any rate, the chance of someone with a normal immune system getting a recurrent shingles infection is less than five percent.