When the itchy red spots of childhood chickenpox disappear and life returns to normal, the battle with the virus that causes chickenpox seems won. But for too many of us this triumph of immune system over virus is temporary. The virus has not been destroyed but remains dormant in our nerve cells, ready to strike again later in life. This second eruption of the chickenpox virus is the disease called shingles or herpes-zoster .
Most adults who have the dormant virus in their body never get shingles. The disease occurs when an unknown trigger causes the virus to become activated.
You cannot develop shingles unless you have had an earlier exposure to chickenpox. The disease most often strikes after age 50. But since shingles is so common, affecting an estimated one million people in the United States each year, cases in young people are not rare. Most people who get shingles have it only once, but it is possible for the outbreak to appear again.
What is Shingles?
Scientists call the virus that causes chickenpox/shingles varicella-zoster virus or VZV. The word "varicella" is derived from "variola," the Latin word for smallpox, another infectious disease that can resemble chickenpox. (Smallpox is a highly contagious and often fatal disease that has disfigured or killed millions of people, especially during the Middle Ages.) “Zoster” is the Greek word for girdle; shingles often produces a girdle or belt of blisters or lesions around one side of the waist. This striking pattern also underlies the condition's common name: shingles comes from “cingulum,” the Latin word for belt or girdle.
VZV belongs to a group of viruses called herpesviruses. This group includes the herpes simplex virus that causes cold sores, fever blisters, mononucleosis, genital herpes (a sexually transmitted disease), and Epstein-Barr virus involved in infectious mononucleosis. Like VZV, other herpesviruses can hide in the nervous system after an initial infection and then travel down nerve cell fibers to cause a renewed infection. Repeated episodes of cold sores on the lips are the most common example.
As early as 1909, scientists suspected that the viruses causing chickenpox and shingles were one and the same. In the 1920s and 1930s, the case was strengthened by an experiment in which children were inoculated with fluid from shingles blisters. Within 2 weeks, about half of the children developed chickenpox. Finally, in 1958, detailed analyses of the viruses taken from patients with either chickenpox or shingles confirmed that the viruses were identical.
Virtually all adults in the United States have had chickenpox, even if it was so mild as to pass unnoticed, and thus may develop shingles later in life. In the original exposure to VZV (chickenpox), some of the virus particles leave the blood and settle into clusters of nerve cells (neurons ) called sensory ganglia, where they remain for many years in an inactive (latent) form. The sensory ganglia, which are adjacent to the spinal cord and brain, relay information to the brain about what the body is sensing - heat, cold, touch, pain.
When the VZV reactivates, it spreads down the long nerve fibers (axons) that extend from the sensory cell bodies to the skin. The viruses multiply, the telltale rash erupts, and the person now has herpes zoster, or shingles. With shingles, the nervous system is more deeply involved than it was during the bout with chickenpox, and the symptoms are often more complex and severe.
Who is at Risk for Shingles?
About 25 percent of all adults, mostly otherwise healthy, will get shingles during their lifetimes, usually after age 50. The incidence increases with age so that shingles is 10 times more likely to occur in adults over 60 than in children under 10. The "burden of illness" (a measure of both severity of zoster pain) is double among individuals greater than age 70 as compared to those 60 - 69 years old.
People with compromised immune systems -- from use of immunosuppressive medications such as prednisone, from serious illnesses such as cancer, or from infection with HIV -- are at increased risk of developing shingles. Shingles is also common in people who are under prolonged stress. These individuals also can have re-eruptions and some may have shingles that never heals. Most people who get shingles re-boost their immunity to VZV and will not get the disease for another few decades.
Youngsters whose mothers had chickenpox late in pregnancy -- 5 to 21 days before giving birth -- or who had chickenpox in infancy, have an increased risk of pediatric shingles. Sometimes these children are born with chickenpox or develop a typical case within a few days (see section entitled "Can Shingles During Pregnancy Harm the Baby?" for more information).
What are the Symptoms of Shingles?
The first sign of shingles is often burning or tingling pain, or itch, in one particular location on only one side of the body. After several days or a week, a rash of fluid-filled blisters appears. These are similar to chickenpox but appear in a cluster rather than scattered over the body. The cluster typically appears in one area on one side of the body. Recent studies have shown that subtle cases of shingles with only a few blisters, or none, are more common than previously thought. These cases may remain unrecognized. Cases without any known lesions are known as zoster sine herpete.
Shingles pain can be mild or intense. Some people have mostly itching; some feel pain from the gentlest touch or breeze. The most common location for shingles is a band, called a dermatome, spanning one side of the trunk around the waistline. The second most common location is on one side of the face around the eye and on the forehead. However, shingles can involve any part of the body. The number of blisters or lesions is variable. Some rashes merge and produce an area that looks like a severe burn. Other patients may have just a few scattered lesions that don't cause severe symptoms.
For most healthy people, shingles rashes heal within a few weeks, the pain and itch that accompany the lesions subside, and the blisters leave no scars. Other people may have sensory symptoms that linger for a few months.
How Should Shingles Be Treated?
Currently there is no cure for shingles, but attacks can be made less severe and shorter by using prescription antiviral drugs such as acyclovir, valacyclovir, or famcyclovir as soon as possible after symptoms begin. Early treatment can reduce or prevent severe pain and help blisters dry faster. Antiviral drugs can reduce by about half the risk of being left with postherpetic neuralgia (see section entitled "What is Postherpetic Neuralgia?"), which is chronic pain that can last for months or years after the shingles rash clears. Doctors recommend starting antiviral drugs at the first sign of the shingles rash, or even if the telltale symptoms indicate that a rash is about to erupt. Even if a patient is not seen by a doctor at the beginning of the illness, it may still be useful to start antiviral medications if new lesions are forming. It is important not to miss any doses or stop taking the medication early. Other treatments to consider are anti-inflammatory corticosteroids such as prednisone. These are routinely used when the eye or other facial nerves are affected.
Most people with shingles can be treated at home.
People with shingles should also try to relax and reduce stress (stress can make pain worse and lead to depression); eat regular, well-balanced meals; and perform gentle exercises, such as walking or stretching to keep active and stop thinking about the pain (but check with your doctor first). Placing a cool, damp washcloth on the blisters -- but not when wearing a topical cream or patch -- can help blisters dry faster and relieve pain.
Is Shingles Contagious?
Shingles is not contagious -- it can't be "caught" from someone else. Shingles occurs when an unknown trigger causes the virus hiding inside the person's body to become activated.
A person with a shingles rash can pass the virus to someone, usually a child, who has never had chickenpox,. In this case, the child will develop chickenpox, not shingles. The child must come into direct contact with the open sores of the shingles rash. Merely being in the same room with a shingles patient will not cause the child to catch chickenpox because during a shingles infection the virus is not normally in the lungs and therefore can't be spread through the air.
Likewise, a person with chickenpox cannot give shingles to someone else -- but they can pass the virus to someone who has never had chickenpox. In cases of chickenpox, the virus can become airborne because it is found in the upper respiratory tract.
Can Shingles Be Prevented?
Immunization with the varicella vaccine (or chickenpox vaccine) - now recommended in the United States for all children between 18 months and adolescence - can protect children from getting chickenpox. People who have been vaccinated against chickenpox are less likely to get shingles because the weak, “attenuated” strain of virus used in the chickenpox vaccine is less likely to survive in the body over decades. Not enough data currently exists to indicate whether shingles can occur later in life in a person who was vaccinated against chickenpox
In May 2006, the U.S. Food and Drug Administration (FDA) approved a VZV vaccine (Zostavax) for use in people 60 and older who have had chickenpox. In March 2011, the FDA extended the approval to include adults 50-59 as well.
Researchers found that giving older adults the vaccine reduced the expected number of cases of shingles by half. And in people who still got the disease despite immunization, the severity and complications of shingles were dramatically reduced. The Shingles Prevention Study - a collaboration between the Department of Veterans Affairs, the National Institute of Allergy and Infectious Diseases, and Merck & Co., Inc. - involved more than 38,000 veterans aged 60 and older. The purpose was to find out how safe the vaccine is, and if it can prevent shingles. Half the study participants were vaccinated with a more potent version of the chickenpox vaccine, developed specifically for use in adults, and half received a placebo vaccine. Neither volunteers nor researchers knew if a particular subject had gotten active or placebo vaccine until after the end of the study (a double-blind study).
During more than 3 years of follow up, the vaccine reduced shingles cases by 51 percent; 642 cases of shingles developed in the placebo group compared with only 315 in the vaccinated group. Pain and discomfort were reduced by 61 percent in people who received the active vaccine but still got shingles. The vaccine also reduced the number of cases of postherpetic neuralgia by two-thirds compared with the placebo.
The shingles vaccine is a preventive therapy and not a treatment for those who already have shingles or postherpetic neuralgia.