Shingles: When a virus awakens with a vengeance

It may be an old disease with a funny name, but shingles is no joke to those who have felt its unrelenting sting. Ask TV comedian David Letterman, who blurted out during a show in 2003 that his eyes were killing him. "I look like somebody gave me a beating. It’s an irritation, inflammation, or infection," Letterman told his audience, adding, "For the love of God, does it hurt!" Letterman was off the air for the next four weeks, recovering from ocular shingles, a less common but potentially dangerous manifestation of the disease.

Chickenpox Virus Redux

Shingles, by any name, hurts. It turns out that the varicella virus that gave you those spectacular chickenpox rashes as a child may have been hiding out for decades in the sensory nerve cells near your spine, until it unexpectedly comes to life in the painful rash of shingles. So, if you’ve ever had chickenpox, you can get shingles, also known as herpes zoster. The varicella-zoster virus, which causes both chickenpox and shingles, is a member of the herpes virus family. In 1995, a vaccine to prevent chickenpox became available and is now in wide use, so most of today’s youngsters will be spared. But most adults had chickenpox in their youth, and to those who did, 10 to 20 percent will get shingles at some time. Although shingles itself isn’t contagious, someone who has the condition can pass the varicella-zoster virus on to a person who has never had chickenpox and is still vulnerable to it.

In otherwise healthy people, shingles is uncommon before age 50. However, about half of people who live to 85 will experience a bout. The risk increases over time because the body’s immune system weakens with age. The risk also increases if the immune system is compromised for other reasons – for example, cancer, HIV infection, or immunosuppressive drugs. As with chickenpox, you will most likely get shingles only once. But once is more than enough.

When A Slumbering Virus Stirs

When the varicella-zoster virus is reactivated, it moves out of the cluster of nerve cells near the spine and travels along the nerve pathways to the skin. These nerves provide the sensory network for specific areas of the skin called dermatomes, which are arranged in a band-like pattern, radiating from the spine. In many cases, the first clue is pain, tingling, or an unpleasant sensation in the skin on one side of the torso, or other dermatome area. Headache and malaise may accompany the pain. At first, the symptoms may be mistaken for other conditions. Within a few days, however, a rash appears so characteristic of shingles that a doctor can make the diagnosis without any tests.

Small, fluid-filled blisters resembling chickenpox break out along dermatomal lines (see illustration) on either the left or right side of the body. Most rashes occur either on the upper torso or around or below the waist (the word shingles comes from the Latin word cingulum, which means belt or girdle). In about 10 to 25 percent of cases, the rash affects the face near the eyes, as what happened to David Letterman. If the virus gets into the eye, it can scar or damage the cornea and lead to blindness. Attacks also occur on the arms and legs. After seven to 10 days, the blisters crust over, and within a few weeks, the rash and usually the pain are gone. The pain that accompanies shingles can be intense, especially when the rash is particularly bad or preceded by pain or tingling.

What To Do About Shingles

If you think you might have shingles, don’t try to tough it out. During the past 20 years, doctors have learned that taking an antiviral agent immediately – within three days of an outbreak – may speed healing of the lesions, reduce the pain, and lessen the chance of postherpetic neuralgia, a painful condition that sometimes follows shingles. For people whose eyes are affected, antiviral treatment is essential to prevent loss of vision and other complications. A doctor can also prescribe medications to help ease the pain.

Treatment should begin within 72 hours after the rash appears. After that, the virus stops replicating and antiviral medications won’t help. Two antiviral agents available in the Philippines – acyclovir (Zovirax) and valaciclovir (Valtrex) – appear equally safe and effective. Acyclovir is taken five times a day for seven days and valaciclovir is taken three times a day for seven days.

Over-the-counter pain relievers, such as aspirin or acetaminophen, are not strong enough to relieve pain during the outbreak. Strong opioid medications may help. Other medications that may reduce the pain are tricyclic antidepressants and certain anticonvulsants. The pain-relieving effects of tricyclic antidepressants may take several weeks to kick in. When used for pain relief, these drugs are prescribed in lower doses than when they are used to treat depression.

Postherpetic Neuralgia

Sometimes, the pain of shingles continues long after the rash heals. The persistent pain is called postherpetic neuralgia ("postherpetic" refers to the period after the herpes zoster rash; "neuralgia" means nerve pain), and it’s caused by damage to nerve cells from the infection. One particularly agonizing feature of postherpetic neuralgia is allodynia, that is, pain resulting from stimuli that rarely cause pain, such as light touch. Some people are in such agony that they cannot get a solid night’s sleep or bear the slight pressure of clothing. They may become withdrawn and depressed.

The prevalence of postherpetic neuralgia is difficult to determine because definitions vary. Some researchers define it as any lingering pain, while others specify pain more than one month, three months, or six months after the appearance of the rash. In a few cases, it lasts more than a year. Like the risk of shingles, postherpetic neuralgia risk increases with age. About 40 percent of people over age 50 who get shingles have some postherpetic neuralgia, as do 50 percent of those over 60, and 75 percent of those over 75. Other risk factors include pain before the rash and severe pain and severe rash during acute shingles. People with all these risk factors have at least a 50 percent chance of having postherpetic neuralgia for six months or more. Fortunately, postherpetic neuralgia is not life-threatening and almost always eventually subsides.

Treating Postherpetic Neuralgia

The antiviral used to treat shingles have no effect on postherpetic neuralgia. Opioids and tricyclic antidepressants don’t always help either. Alleviating pain often requires a certain amount of trial and error and a combination of medications. A drug that’s effective in one person may not help someone else.

In the past few years, some new treatments have emerged. The first drug approved specifically for postherpetic neuralgia by the US Food and Drug Administration (FDA) is not a pill, but a patch. Introduced in 1999, the Lidoderm patch contains lidocaine, the same medication a dentist may inject into your gum before filling a cavity or doing a root canal. The patch is applied directly over the sorest area of the skin. Because lidocaine is not taken internally and is absorbed from the patch only in tiny amounts, the treatment is considered quite safe.

In 2002, the FDA approved the use of the anticonvulsant agent, gabapentin (Neurontin) for managing postherpetic neuralgia. Although other anticonvulsants have been used for years to relieve pain related to nerve damage, clinical trials have yielded solid proof that gabapentin – well-tolerated and safe in the elderly – is effective not only for pain relief, but also in improving the quality of life of people with postherpetic neuralgia. Recently, another medication – pregabalin (Lyrica) has been introduced for the treatment of neuropathic pains in adults. Initial clinical experience had been encouraging.

Hopes For A Vaccine

In the United States, a nationwide Shingles Prevention Study, began in 1998, enrolled 38,546 people aged at least 60 years, who had had chickenpox as children. They were randomized into the vaccine or placebo group. They were given a reformulated version of the childhood vaccine, and their incidence of shingles was tracked. The results were recently published in the New England Journal of Medicine (2005: 352: 2271-2284)

Among the vaccine group, there were 315 confirmed cases of herpes zoster and 27 cases of postherpetic neuralgia. Among the control group, there were 642 cases of herpes zoster and 80 cases of postherpetic neuralgia. The vaccine reduced the incidence of herpes zoster by 51 percent and of postherpetic neuralgia by 67 percent. The study concluded that the vaccine was effective in significantly preventing herpes zoster and postherpetic neuralgia in people aged 60 years or older.

It’s a promising development in our fight to control one of humankind’s oldest, most mysterious, and most painful conditions.