Shingles
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.
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Who is at Risk for Shingles?
About 25 percent of all adults, mostly otherwise healthy, will get shingles during their lifetimes, usually after age 40. The incidence increases with age so that shingles is 10 times more likely to occur in adults over 60 than in children under 10. 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 special risk of developing shingles. 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.
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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, similar to chickenpox, appears in one area on one side of the body. Recent studies have shown that subtle cases of shingles with only a few lesions, or none, are more common than previously thought. These cases will usually 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 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?
Shingles attacks can be made less severe and shorter by using prescription antiviral drugs: acyclovir, valacyclovir, or famcyclovir. Acyclovir is available in a generic form, but the pills must be taken five times a day, whereas valacyclovir and famcyclovir pills are taken three times a day. It is important not to miss any doses and not to stop taking the medication early. 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 still forming. Other treatments to consider are anti-inflammatory corticosteroids such as prednisone. These are routinely used when the eye or other facial nerves are affected.
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Is Shingles Contagious?
A person with a shingles rash can pass the virus to someone, usually a child, who has never had chickenpox, but 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.
People with chickenpox cannot communicate shingles to someone else although they can of course pass the chickenpox on 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.
Shingles occurs when an unknown trigger causes the virus hiding inside the person's body to become activated. Unlike chickenpox, shingles can't be "caught" from someone else.
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Can Shingles Be Prevented?
Chickenpox vaccine
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. But a definitive answer to the question of whether shingles can occur later in life in a person vaccinated against chickenpox will only be provided when enough data have been gathered over the next several decades.
Some scientists believe that immunizing children against chickenpox increases the risk of shingles in adults who were not themselves immunized during childhood. This is because when adults care for children sick with chickenpox, it reboosts their own immunity that keeps the virus in their nerve cells from reactivating as shingles. With fewer children coming down with chickenpox, there are fewer opportunities for this "reboosting" of adult immunity, and so there may be more shingles cases for the next 40-50 years.
Shingles vaccine
In May 2006, the Food and Drug Administration approved a VZV vaccine (Zostavax) for use in people 60 and older who have had chickenpox. When the vaccine becomes more widely available, many older adults will for the first time have a means of preventing shingles.
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 only a preventive therapy and not a treatment for those who already have shingles or postherpetic neuralgia.
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What is Postherpetic Neuralgia?
Sometimes, particularly in older people, shingles pain persists long after the rash has healed. This postherpetic neuralgia can be mild or severe - the most severe cases can lead to insomnia, weight loss, depression, and disability. Postherpetic neuralgia is not directly life-threatening. About a dozen medications in four categories have been shown in clinical trials to provide some pain relief. These include:
Tricyclic antidepressants (TCAs): TCAs are often the first type of drug given to patients suffering from postherpetic neuralgia. The TCA amitryptiline was commonly prescribed in the past, but although effective, it has a high rate of side effects. Desipramine and nortriptyline have fewer side effects and are therefore better choices for older adults, the most likely group to have postherpetic neuralgia.
Common side effects of TCAs include dry eyes and mouth, constipation, and grogginess. People with heart arrhythmias, previous heart attacks, or narrow angle glaucoma should usually use a different class of drugs.
Anticonvulsants: Some drugs that reduce seizures can also treat postherpetic neuralgia because seizures and pain both involve abnormally increased firing of nerve cells. An antiseizure medication, carbamazepine, is effective for postherpetic neuralgia but has rare, potentially dangerous side effects so a newer anticonvulsant, gabapentin, is far more often prescribed. Side effects of the drug include drowsiness or confusion, dizziness, and sometimes ankle swelling.
Opioids: Opioids are strong pain medications used for all types of pain. They include oxycodone, morphine, tramadol, and methadone. Opioids can have side effects - including drowsiness, mental dulling, and constipation - and can be addictive, so their use must be monitored carefully in those with a history of addiction.
Topical local anesthetics: Local anesthetics applied directly to the skin of the painful area affected by postherpetic neuralgia are also effective. Lidocaine, the most commonly prescribed, is available in cream, gel, or spray form. It is also available in a patch that has been approved by the Food and Drug Administration for use specifically in postherpetic neuralgia. With topical local anesthetics, the drug stays in the skin and therefore does not cause problems such as drowsiness or constipation. Capsaicin cream may be somewhat effective and is available over the counter, but most people find that it causes severe burning pain during application.
Postherpetic itch
The itch that sometimes occurs during or after shingles can be quite severe and painful. Clinical experience suggests that postherpetic itch is harder to treat than postherpetic neuralgia. Topical local anesthetics (which numb the skin) provide substantial relief to some patients. Since postherpetic itch typically develops in skin that has severe sensory loss, it is particularly important to avoid scratching. Scratching numb skin too long or too hard can cause injury.
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What are Other Complications of Shingles?
People with ophthalmic shingles -- lesions in or around the eye and forehead -- can suffer painful eye infections, and in some cases immediate or delayed vision loss. People with shingles in or near the eye should see an ophthalmologist immediately. Shingles infections within or near the ear (Ramsay-Hunt syndrome) can cause hearing or balance problems as well as weakness of the muscles on the affected side of the face. In rare cases, shingles can spread into the brain or spinal cord and cause serious complications such as stroke or meningitis (an infection of the membranes outside the brain and spinal cord). People with shingles need to seek immediate medical evaluation if they notice neurological symptoms outside the region of the primary shingles attack. People who are immunosuppressed, whether from diseases such as HIV or medications, have an increased risk of serious complications from shingles. Most commonly, they get shingles that spreads to involve more parts of the body, or shingles rashes that persist for long periods or return frequently. Many such patients are helped by taking antiviral medications on a continuous basis.
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Can Infection with VZV During Pregnancy Harm the Baby?
Many mothers-to-be are concerned about any infection contracted during pregnancy, and rightly so because some infections can be transmitted across the mother's bloodstream to the fetus or can be acquired by the baby during the birth process. VZV infection during pregnancy poses some risk to the unborn child, depending upon the stage of pregnancy. During the first 30 weeks, maternal chickenpox may, in some cases, lead to congenital malformations. Such cases are rare and experts differ in their opinions on how great the risk is. Most experts agree that shingles in a pregnant woman, a rare event, is even less likely to cause harm to the unborn child.
If a pregnant woman gets chickenpox between 21 to 5 days before giving birth, her newborn can have chickenpox at birth or develop it within a few days. But the time lapse between the start of the mother's illness and the birth of the baby generally allows the mother's immune system to react and produce antibodies to fight the virus. These antibodies can be transmitted to the unborn child and thus help fight the infection. Still, a small percent of the babies exposed to chickenpox in the 21 to 5 days before birth develop shingles in the first 5 years of life because the newborn's immune system is not yet fully functional and capable of keeping the virus latent.
What if the mother contracts chickenpox at the time of birth? In that case the mother's immune system has not had a chance to mobilize its forces. And although some of the mother's antibodies will be transmitted to the newborn via the placenta, the newborn will have little ability to fight off the attack because its immune system is immature. If these babies develop chickenpox as a result, it can be fatal. They are given zoster immune globulin, a preparation made from the antibody-rich blood of adults who have recently recovered from chickenpox or shingles, to lessen the severity of their chickenpox.
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