Herpes Zoster, also known as Shingles, is the reactivation of varicella zoster virus (one of the Herpesviridae group), leading to a crop of painful blisters over the area of a dermatome. In Italy and in Malta, it is sometimes referred to as "St. Anthony's fire".
Prior to implementation of the universal varicella vaccination program in the U.S., incidence of shingles increased with advancing age. The incidence rate in children aged less than 10 years was approximately 70 cases/100,000 person-years, increasing to 550 cases/100,000 person-years among adults aged 50 to 59 years. Historically, it was thought that shingles incidence increased due to an age-related decline in immunity; however, recent studies suggest that incidence of shingles is linked to the reduced frequency of periodic exogenous (outside) exposures to children with varicella (chickenpox) due to the increasing vaccination of that population. These exposures produced an immunologic boost that helped suppress the reactivation of shingles. Shingles incidence is high in the elderly (over 60), as well as in any age group of immunocompromised patients. It affects some 1 million people per year in the United States and can involve excruciating pain. Many patients develop a painful condition called postherpetic neuralgia which is often difficult to manage.
In some patients, herpes zoster can reactivate subclinically with pain in a dermatomal distribution without rash. This condition is known as zoster sine herpete and may be more complicated, affecting multiple levels of the nervous system and causing multiple cranial neuropathies, polyneuritis, myelitis, or aseptic meningitis.
Often, pain is the first symptom. This pain can be characterized as stinging, tingling, numbing, or throbbing, and can be pronounced with quick stabs of intensity. Then 1-3 crops of red lesions develop, which gradually turn into small blisters filled with serous fluid. A general feeling of unwellness often occurs. In some cases, the rash does not form blisters, but has an appearance much like urticaria ("hives").
As long as the blisters have not dried out, HZ patients may transmit the virus to others. This could lead to chickenpox in people (mainly young children) who are not yet immune to this virus.
Chickenpox virus can remain dormant for decades, and does so inside the ganglion near the spinal cord. As the virus is reactivated it spreads down peripheral nerve fibers and produces intense pain. The blisters therefore only affect one area of the body and do not cross the midline. They are most common on the torso, but can also appear on the face (where they are potentially hazardous to vision) or other parts of the body.
Outbreaks occur for many different reasons, most of which are a result of events which decrease the immune system such as aging, severe emotional stress, severe illness or long-term use of corticosteroids. There have been recorded cases of outbreaks occurring due to unmanaged stress or other stresses to the skin such as pinching in more sensitive areas of the skin (nipples, ears, and underarms), scratching, or biting.
The rash and pain usually subside within 3 to 5 weeks. The most common chronic complication of herpes zoster is postherpetic neuralgia. Pain that persists for longer than one to three months after resolution of the rash is generally accepted as the sign of postherpetic neuralgia. Sometimes serious effects including partial facial paralysis (usually temporary), ear damage, or encephalitis may occur. Shingles on the upper half of the face (the first branch of the trigeminal nerve) may result in eye damage and require urgent ophthalmological assessment. Ocular complications occur in approximately one half of patients with involvement of the ophthalmic division of the trigeminal nerve. These complications include mucopurulent conjunctivitis, episcleritis, keratitis and anterior uveitis. Cranial nerve palsies of the third, fourth and sixth cranial nerves may occur, affecting extraocular motility.
Since shingles is a reactivation of a virus contracted previously—often decades earlier—it cannot be induced by exposure to another person with shingles or chickenpox. Those with active blisters, however, can spread chickenpox to others who have never had that condition and who have not been vaccinated against it.
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