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Culebrilla: Esperanza en la Investigación
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IntroductionIntroduction 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 .
"I was having exams at college and I got a rash in a band around one side of my waist. The spots were very painful. At first
I thought it was chickenpox, but I'd had that years before," recalls a young woman who had shingles in her twenties.
The young woman's memory was correct. She did have chickenpox as a child. You cannot develop shingles unless you have had an earlier exposure to chickenpox, and most people
who get chickenpox are at risk for shingles. The woman had the typical one-sided band of rash and pain of this common neurological
disorder. Her age was unusual, however.
While young people do develop shingles, the disease most often strikes after age 40. But since shingles is so common, affecting
an estimated one-quarter of Americans at some point during their lifetimes, cases in young people are not rare.
* Terms in Italics are defined in the Glossary.
What is Shingles? 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 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 (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, 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.
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.
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.
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.
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.
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.
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.
What Research is Being Done? Because of nervous system involvement, the chickenpox/shingles virus is studied by the National Institute of Neurological
Disorders and Stroke, a part of the National Institutes of Health. The National Institute of Allergy and Infectious Diseases,
the National Cancer Institute, the National Institute on Aging, and the National Eye Institute also support research on shingles.
Medical research on shingles has two main goals. The first is to develop drugs to fight the disease and to prevent or treat
its complications, especially postherpetic neuralgia. The second is to understand the disease well enough to prevent it, especially
in people at high risk. Scientists need to learn much more about the VZV, particularly how it becomes latent in the body and
what induces it to become active again. Scientists suspect that the VZV DNA is inserted into one of the chromosomes of the
nerve cell - the units that house the cell's own genetic material.
A healthy immune system protects against all kinds of diseases, but people with faulty immunity are vulnerable to many illnesses,
including shingles. Antibodies, one of the immune system's major defense mechanisms against infection, are not very helpful
against shingles. The immune cells that appear to combat shingles are two types of white blood cells: T lymphocytes and macrophages.
Scientists are trying to find ways to boost the activity of these cells - especially in patients at high risk for severe or
disseminated shingles (a rare condition in which the virus spreads to other areas of the body, sometimes vital areas such
as the blood or the lungs).
Other researchers are studying how VZV infects neurons. In particular, they are looking at how the virus assembles in and
exits out of nerve cells, with the goal of blocking this important step. In another study, researchers are developing animal
models to evaluate VZV vaccines. Their findings may lead to improved vaccines that protect against varicella or prevent it
from establishing latent infection or reactivation to cause shingles and postherpetic neuralgia.
Other research is aimed at finding new methods for identifying the biological differences between people who suffer from or
escape long-term postherpetic neuralgia pain after shingles. The goals of this research are to identify ways to reduce the
risk of postherpetic neuralgia after shingles.
“On Catching Chickenpox . . . but not Catching Shingles” Chickenpox and shingles are caused by the same virus - varicella-zoster (VZV). When a person, usually a child, who has not
received the chickenpox vaccine (which became available in the United States in 1995) is exposed to VZV, he or she usually
develops chickenpox, a highly contagious disease that can be spread by breathing as well as by contact with the rash. The
infection begins in the upper respiratory tract where the virus incubates for 15 days or more. VZV then spreads to the bloodstream
and migrates to the skin, giving rise to the familiar chickenpox rash.
In contrast, you can't catch shingles from someone else. You must already have been exposed to chickenpox and harbor the virus
in your nervous system to develop shingles. When reactivated, the virus travels down nerves to the skin, causing the painful
shingles rash. In shingles, the virus does not normally spread to the bloodstream or lungs, so the virus is not shed in air.
Because the shingles rash contains active virus particles, someone who has never had chickenpox can catch it from exposure
to a shingles rash.
For more information on neurological disorders or research programs funded by the National Institute of Neurological Disorders and Stroke, contact the Institute's Brain Resources and Information Network (BRAIN) at:
BRAIN
P.O. Box 5801
Bethesda, MD 20824
(800) 352-9424
http://www.ninds.nih.gov
Information also is available from the following organizations:
American Chronic Pain Association (ACPA) P.O. Box 850 Rocklin, CA 95677-0850 ACPA@pacbell.net http://www.theacpa.org Tel: 916-632-0922 800-533-3231 Fax: 916-632-3208 Provides self-help coping skills and peer support to people with chronic pain. Sponsors local support groups throughout the U.S. and provides assistance in starting and maintaining support groups. |
VZV Research Foundation
[For Research on Varicella Zoster] 24 East 64th Street 5th Floor New York, NY 10021 vzv@vzvfoundation.org http://www.vzvfoundation.org Tel: 212-371-7280 Fax: 212-838-0380 Non-profit organization solely combating VZV infections: chickenpox, shingles and post-herpetic neurgalia (PHN). Supports research that may lead to a better understanding of VZV infections and to advances in their prevention, treatment and cure. |
National Foundation for the Treatment of Pain P.O. Box 70045 Houston, TX 77270 NFTPain@cwo.com http://www.paincare.org Tel: 713-862-9332 Fax: 713-862-9346 Not-for-profit organization dedicated to providing support for patients who are suffering from intractable pain, their families, friends and the physicians who treat them. Offers a patient forum, advocacy programs, information, support resources, and direct medical intervention. |
Glossary acyclovir - one of three available antiviral drugs that can reduce the severity and duration of a shingles attack if given soon after
onset.
capsaicin - an active ingredient in hot chili peppers used in topical ointments to relieve pain. It appears to work by reducing a chemical
substance found at nerve endings and involved in transmitting pain signals to the brain. While somewhat effective for postherpetic
neuralgia, it can cause severe burning in some patients.
carbamazepine - a drug that works both as an anticonvulsant and a pain reliever.
chickenpox - an acute contagious disease that usually occurs in children and is caused by the varicella-zoster virus.
desipramine - an antidepressant often prescribed to help reduce the pain from postherpetic neuralgia. Doctors often prescribe it because
it has fewer side effects than some other antidepressants.
famcyclovir - one of three available antiviral drugs that can reduce the severity and duration of a shingles attack if given soon after
onset.
gabapentin -- an antiseizure medicine that is also used as a pain reliever.
herpes zoster - the medical term for shingles; an infection caused by the varicella-zoster virus, one of the herpesviruses family of viruses.
herpes simplex - the medical term for a related but different virus that causes repeated mild blisters of the skin or mucous membrane. Herpes
simplex rashes can return many times, whereas shingles usually appears no more than once or twice in a person's lifetime.
herpesviruses - a large family of viruses that cause a number of related conditions including, but not limited to, oral and genital herpes
simplex, varicella (chickenpox), and herpes-zoster (shingles).
immunosuppressed - having a weakened immune system. Common causes are certain illnesses (HIV, some cancers) or use of certain drugs such as
prednisone.
latent - hidden, dormant, inactive. The virus that causes chickenpox remains hidden in the nervous system after the initial attack
of chickenpox is over. When it becomes reactivated, usually many years later, the virus can cause shingles.
lidocaine - a pain-killing drug sometimes used for treating postherpetic neuralgia. It is available in an adhesive fabric patch that
can be placed on the skin directly over the site of the pain.
neuron- the functional cell of the brain and nervous system.
nortriptyline- an antidepressant often prescribed to help reduce the pain from postherpetic neuralgia. Doctors often prescribe it because
it has fewer side effects than some other antidepressants.
postherpetic itch - severe, painful, and difficult to treat itching that sometimes accompanies postherpetic neuralgia. Topical local anesthetics
provide relief to some patients.
postherpetic neuralgia - a condition characterized by pain that persists more than 3 months after healing of a shingles rash; caused by damage to
the nervous system.
prednisone - an anti-inflammatory corticosteroid drug routinely given to shingles patients when an eye or other facial nerve is involved.
valacyclovir - one of three available antiviral drugs that can reduce the severity and duration of a shingles attack if given soon after
onset.
varicella-zoster virus - a virus that causes two distinct diseases, chickenpox and shingles. It is a member of the herpesvirus family. "Varicella"
is Latin for little pox; "zoster" is the Greek word for girdle. Medically, zoster is sometimes used as a synonym for shingles.
zoster sine herpete - a case of shingles in which there are no blisters or other signs of the illness on the skin.
NIH Publication No. 06-307
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Last updated July 31, 2008