sections include: chicken pox in childhood, shingles and the immune system, diagnosis and treatment
Shingles, or (to use the medical term) herpes zoster, is characterized by pain and a localized rash. The rash usually covers a few inches of skin encompassing one to three dermatomes, each dermatome being the area supplied by a single nerve root. The rash of shingles is characterized by many small blisters superimposed on an angry red, inflamed base. Shingles always occurs on only one side of the body at a time.
The pain of shingles is severe; most patients describe it as burning. The area usually becomes exquisitely sensitive to touch (the medical term for this is allodynia). At the same time, the inflamed skin may be less sensitive to a painful stimulus, such as a pinprick (this is called hypalgesia). Because of allodynia, people with shingles often wear loose-fitting clothes. They may be reluctant to rub the affected skin when washing or showering.
The rash and pain usually develop within a few days of each other, although the pain can come first by many days or even weeks, making the diagnosis difficult. Sometimes people ascribe their rash to exposure to toxic materials, allergies, or animal bites.
Chicken Pox in Childhood
The same virus that produces chicken pox (varicella) causes shingles. Typically, when children develop chicken pox they have a rash over most of the body rather than a small portion. This is because individuals encountering the varicellazoster virus (VZV) for the first time have no immunity to it. Children almost always survive chicken pox, developing strong resistance to VZV. However, there are two important residual effects. First, the virus does not disappear—it becomes hidden, or latent, in collections of nerve cells in ganglia. Second, as we age, our immunity to VZV declines naturally. Thus the latent virus can reemerge from ganglia decades after chicken pox. Fortunately, most people still have some immunity to VZV that limits its reactivation to one area of the skin.
VZV is ubiquitous. Nearly everyone in the world develops chicken pox; each year, more than 3 million American children have it. Even some adults who have never had chicken pox have been found to have VZV antibodies, meaning their original infection was subclinical (no history of chicken pox). Thus, nearly everyone has the virus latent in their ganglia, with the potential to reactivate.
People can develop shingles at any age, even less than ten years after chicken pox. However, it does not usually appear until after age 50. The longer a person lives, the more likely he or she is to develop shingles. As our population grows older on average, we will have more cases. Even now, over half a million Americans develop shingles every year. Men and women are equally affected, as are all ethnic groups.
Shingles and the Immune System
Any medical condition that impairs an individual’s immune system also predisposes that person to shingles. Years ago, people with cancer, lymphoma, or leukemia were the most likely to develop shingles. Such people usually have poor resistance to infections and are frequently treated with drugs and X rays that further impair their immune response. Many organ transplant recipients also develop shingles as they take immunosuppressive drugs to prevent rejection of their newly received tissue.
Today the condition most commonly associated with shingles is AIDS, which also weakens a person’s immune response. Shingles can occur any time during the course of AIDS, and sometimes it is the first sign that a person has encountered the human immunodeficiency virus (HIV) that causes AIDS.
For a healthy person to develop shingles before age 50 does not mean the individual has cancer or AIDS. Although the disorder is most common in older people, it can even affect a teenager. Its appearance is usually not significant. However, if the individual is at high risk for HIV infection because of drug abuse or sexual practices, doctors will usually recommend an HIV test.
Diagnosis and Treatment
Most doctors can readily diagnose shingles from hearing about the severe pain and seeing the characteristic rash over a few inches of a person’s skin. Fortunately, for most people the immune system is already at work driving the virus back to the latent state, and we have treatments to help.
There is also a rare condition called zoster sine herpete (shingles without the rash), which is harder to diagnose. This is characterized by chronic pain, usually in the same three- to five-inch distribution in which a rash usually occurs, but a rash never develops. Blood and cerebrospinal fluid tests can sometimes show that the VZV virus is causing this pain. Although these cases are rare, patients can be treated effectively.
VZV is one of eight known human herpes viruses, the only family of viruses for which we have effective antiviral therapy. The three main drugs we use today are acyclovir (Zovirax), valacyclovir (Valtrex), and famciclovir (Famvir). Acyclovir has been used the longest; people with shingles need to take it five times a day for seven to ten days. In contrast, famciclovir only needs to be taken three times a day, so many physicians prefer it.
For people over age 50, most physicians prescribe one of the oral antiviral agents (usually famciclovir or valacyclovir) for a period of seven to ten days. For people who have normal immune systems and are under 50, however, many doctors prescribe pain-relieving medicines only. Antiviral agents are not required. Other physicians give antiviral drugs even to young people because they are safe.
When immunocompromised patients develop shingles, doctors usually prescribe intravenous acyclovir, administered in a hospital or by a visiting nurse at the patient’s home, for seven to ten days. This treatment is designed to prevent the virus from spreading. When the virus spreads beyond the usual two or three dermatomes to all areas of the skin, and to the liver, lungs, and other organs, the condition is called disseminated zoster. It can be fatal if not treated early.
Along with antiviral agents, physicians will prescribe medication for pain. Usually aspirin and anti-inflammatory agents are not enough. Often treatment requires acetaminophin with codeine (Myapap with codeine). Other medications prescribed are carbamazepine (Tegretol) and gabapentin (Neurontin), two medicines usually used to prevent seizures that can also reduce pain in some people with shingles.
In individuals under 50, the rash begins to resolve within a week and pain disappears within a month. In individuals over 50, and particularly over 60, however, the rash disappears but pain may persist for months or years. This condition is called postherpetic neuralgia (PHN). Forty to fifty percent of individuals over 60 develop it. This is a difficult problem because it requires continued doses of strong medications. All the drugs we have to treat shingles have side effects, such as confusion, unsteadiness, lethargy, and impaired balance. Furthermore, oxycodone is addictive. Elderly people are particularly sensitive to these medications. Other long-term treatments include anesthetics applied to the skin, such as lidocaine patches (which require a prescription) or Aspercreme or Flexall 454 (which can be purchased over the counter). Physicians frequently combine topical agents with the systemic drugs described above.
Healthy individuals with no known condition impairing their immune response have less than a 5 percent recurrence rate of shingles. In contrast, in immunosuppressed patients, shingles may recur. The VZV may even spread to other parts of the body and produce new neurological conditions. These may include the following:
- In the spinal cord, myelitis—pain, tingling, and weakness in the legs, along with bladder and bowel incontinence.
- In arteries outside the brain, granulomatous arteritis—shingles on the face followed a few weeks later by a stroke that produces paralysis of the opposite side of the body.
- In arteries around and inside the brain, encephalitis— headache, fever, weakness of one or both sides of the body, and trouble with speech and balance.
Both brain conditions are serious and require intravenous treatment with acyclovir for seven to ten days. Many doctors also give steroids for their anti-inflammatory effect.
In addition to research on new drugs and the chicken pox vaccine, many investigators are studying the physical state of VZV in latently infected ganglia, often from people who have recently died of unrelated causes. Understanding the latent virus’s DNA, RNA, and proteins may lead to drugs that prevent it from reactivating, thus eradicating shingles and its attendant serious neurologic complications.
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