Shingles (herpes zoster) is a viral infection caused by the varicella-zoster virus (VZV), the same virus that causes chicken pox. After a person has had chickenpox, VZV remains in a dormant (inactive) state in the nerve roots for the rest of their life. VZV may reactivate years later in the form of a painful skin rash known as shingles. The disorder is relatively common, with about 500,000 cases reported annually, according to the National Institute of Allergy and Infectious Diseases.
Why VZV becomes active after a prolonged period of dormancy is unknown. Research suggests that several factors may play a role in the development of shingles (e.g., weakened immune system, stress, fatigue).
A physician can often diagnose a shingles rash by physical examination. However, a physician may perform tests for confirmation (e.g., Tzank smear). Most cases of shingles go away without treatment. A physician may recommend some treatments to alleviate symptoms.
Anyone with VZV can potentially have an outbreak, making shingles impossible to prevent once the virus is in the body. People who have been vaccinated or who have never had chickenpox cannot develop shingles but may develop chickenpox following exposure to VZV. According to the American Academy of Dermatology (AAD), about 20 percent of people exposed to VZV develop shingles, with most of these outbreaks being relatively mild and without recurrence.
Shingles (herpes zoster) is a viral infection caused by varicella-zoster virus (VZV), the same virus that causes chickenpox. After a person has had chickenpox, VZV remains in a dormant (inactive) state in the nerve roots for the remainder of their life. VZV may re-activate itself years later in the form of a painful skin rash known as shingles. About 500,000 cases of shingles are reported annually in the United States, according to the National Institute of Allergy and Infectious Diseases. About 20 percent of patients who have had chickenpox will develop shingles in their lifetime.
A rash usually appears about two to three days after VZV has become active in the nerves and reached the skin of the affected area. Why VZV emerges from dormancy is unknown, though it may occur in relation to a number of factors (e.g., stress, impaired immune system). The rash consists of small red blisters (vesicles) that resemble the early stages of chickenpox. It may spread over the next three to five days to include a larger area of the body.
Rash blisters or lesions most often appear along a single dermatome (a segment of the skin supplied by specific spinal nerves) and on only one side of the body. Occasionally two or three adjacent dermatomes may be involved. The thoracic (chest) and lumbar (lower back) dermatomes are most often affected by shingles. Rarely, a patient may experience pain but not the appearance of shingles itself (zoster sine herpete).
Repeated attacks of shingles are possible. However, most episodes are mild and occur once, unless the patient is immunosuppressed (e.g., HIV patient, organ transplant recipient, chemotherapy patient). Widespread or recurrent shingles may indicate an underlying problem with the immune system. Shingles most often affects adults of both genders aged 55 and older. This may be due to a breakdown in VZV immunity as people age. However, shingles may potentially affect anyone infected with VZV due to an earlier chickenpox infection.
Some people may experience post-herpetic neuralgia, a condition that causes the skin to remain painful for months or sometimes years after a shingles rash has gone away. Post-herpetic neuralgia pain can be slightly uncomfortable or severe and incapacitating, resulting in depression, anxiety and sleeping difficulties. The rate of incidence increases significantly with age, usually occurring in patients aged 60 and older.
Rarely, other potentially serious complications may occur in association with shingles, including:
- Bacterial skin infection
- Inflammation of the cornea (keratitis) or membranes of the eye (uveitis)
- Nerve damage
- Meningitis (inflammation of the membranes that protect the brain and spinal cord)
- Encephalitis (inflammation of the brain)
- Myelitis (inflammation of the spinal cord)
Risk factors and causes of shingles
Shingles (herpes zoster) is an infection caused by varicella-zoster virus (VZV), the virus responsible for chicken pox. After a person recovers from chickenpox, VZV travels from the skin along the nerves and into a section of the nerves located near the spinal cord (dorsal root ganglia). The virus may lie dormant in the dorsal root ganglia for decades. However, in some people it reactivates.
Why VZV becomes active after a prolonged period of dormancy (inactivity) is unknown. Research suggests that several factors may play a role in who develops shingles. These factors include:
- A weakened immune system due to age, organ transplantation, disease (e.g. HIV/AIDS) or treatment (e.g., radiation, medication)
- Injury to the area of the skin where the rash subsequently occurs
Once reactivation of the virus is initiated it begins to multiply within the dorsal root ganglia. The damage this causes within the nerve triggers pain. The virus then makes its way back along the nerve to the skin, where it presents as a rash.
Shingles is only contagious from direct contact with open blisters. Individuals who have not had chickenpox or received the vaccine and are then exposed to shingles are not at risk of developing shingles, but may develop chickenpox. Covering open blisters may be an effective way of preventing the spread of VZV to others. Likewise, scratching of blisters may worsen symptoms or spread VZV to others and should be avoided.
Medical attention should be sought immediately if a rash with blisters develops on the nose or near the eyes. When this occurs, VZV may spread to the eye and cause eye damage or visual loss. In addition, pregnant women and individuals with weakened immune systems have an increased risk for complications and should seek medical attention if shingles develops.
Signs and symptoms of shingles
Shingles is a viral infection caused by the same virus that causes chicken pox, the varicella-zoster virus [VZV]. Shingles is characterized by a painful, patchy skin rash with small blisters.
It may affect many different body parts depending on which dermatomes (the area of the body supplied by a spinal cord nerve) are involved. Shingles tends to be more painful and cause less itching than chickenpox.
In most cases, the dominant symptom is extreme sensitivity or pain along specific bands of nerves on one side of the body. It is sometimes accompanied by other vague symptoms, such as numbness, tingling and itching.
Two to five days following the initial sensation, a rash consisting of red blisters appears on the surface of the skin in the same location. The blisters then break, forming small ulcers that dry and crust over. The rash usually lasts about two or three weeks before it scabs and disappears, sometimes leaving pink or scarred skin.
Rash blisters or lesions most often appear along a single dermatome, and on only one side of the body, though two or three adjacent dermatomes may occasionally be involved. The thoracic (chest) and lumbar (lower back) dermatomes are most often affected by shingles. Some patients may develop a few scattered blisters on the body separate from the rash. This occurs when small amounts of VZV are released from the affected nerve areas into the bloodstream and spread to other locations.
Blisters that occur in the mouth or eye can lead to permanent blindness if left untreated and require immediate medical attention. In addition, involvement of the facial nerve may cause serious side effects (e.g., facial paralysis, hearing loss).
In most cases, the skin returns to normal and the pain subsides after four to five weeks. However, some patients may experience post-herpetic neuralgia, a condition where the pain from shingles lasts for months or years after the lesions disappear. The lasting pain may be minor but is more often severe in nature. In some cases, a slight breeze blowing past the skin or a light sheet touching the skin can cause extreme pain.
Other symptoms that may be experienced either prior to or during an outbreak of shingles include:
- Upset stomach
Diagnosis methods for shingles
To diagnose shingles, a physician will take the patient's complete medical history and perform a physical examination. Observance of blisters or rash from shingles is often all that is necessary to permit a diagnosis. However, a doctor may choose to perform tests for confirmation, including:
- Tzanck smear. Opening a blister to collect fluid and skin cells for analysis under a microscope. A Tzanck smear may reveal viral changes in cells, though it cannot distinguish varicella-zoster virus (VZV) from herpes simplex virus (HSV) and may not be appropriate for all patients.
- Direct fluorescent antibody (DFA) test. A test that detects substances in the body that produce an immune response. DFA testing differentiates between VZV and HSV and may be useful in diagnosing shingles, though it is seldom necessary.
- Skin biopsy. Collection of a sample of skin rash for microscopic analysis. Cultures of biopsied tissue may also be performed if there are no unbroken blisters available. DNA (deoxyribonucleic acid) indicating VZV may be detected with a skin biopsy.
When patients seek medical attention for their symptoms before the rash appears, diagnosis may be difficult. In fact, the severe pain that often precedes the rash is often misdiagnosed as a result of kidney stones, gallstones, appendicitis, heart attacks and other conditions.
Treatment and prevention of shingles
Most cases of shingles go away naturally without treatment. However, some treatments may be effective at reducing painful symptoms and speeding recovery.
Antiviral drugs (e.g., acyclovir, valacyclovir) administered orally are the most common treatment for shingles. They promote more rapid healing while reducing the pain and duration of the outbreak. Taking antiviral drugs within 72 hours of an episode of shingles increases the potential benefits of treatment. Antiviral drugs and tricyclic antidepressants (e.g., doxepin) may also be beneficial in treating pain associated with post-herpetic neuralgia, a condition in which the pain from shingles lasts for months or years after the lesions disappear. Some patients may receive cortisone injections along with antiviral drugs, or over-the-counter medications (e.g., ibuprofen, aspirin) for decreasing pain and inflammation. Those who develop a bacterial infection as the result of scratching may also be prescribed antibiotics.
Other home treatment methods that may be beneficial in treating shingles symptoms include:
- Cool water compresses. May help soothe pain and reduce the chance of skin infection.
- Antihistamines. Used to help prevent itching.
- Keeping the area clean and dry. Minimizes pain and accelerates healing.
- Avoiding scratching. Scratching of blisters may spread germs to others or worsen symptoms.
Anyone with varicella-zoster virus (VZV) can potentially have an outbreak of shingles, making it impossible to prevent once the virus is in the body. However, according to the American Academy of Dermatology (AAD), only about 20 percent of people with VZV later develop shingles, and most of those outbreaks are relatively mild and do not recur. Individuals without immunity to shingles can prevent VZV infection by avoiding contact with children and adults who have chickenpox or shingles, though it is possible for VZV to be spread before signs of infection (e.g., rash) are present.
The VZV or chickenpox vaccine may decrease the likelihood of shingles by strengthening the immune system's ability to keep the virus inactive. The varicella vaccine has significantly decreased the number of annual chickenpox infections since its introduction in 1995. Routine vaccinations for children are recommended. Adolescents and adults can also receive the vaccine.
Researchers are investigating the use of additional (booster) doses of chickenpox vaccine to determine if they may prevent shingles from developing in people with VZV. In addition, other research is being conducted to find new methods for treating shingles and related complications.
Questions for your doctor regarding shingles
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following shingles-related questions:
- Will I require tests to confirm my diagnosis of shingles?
- What shingles-related complications am I at risk for?
- My kids have yet to be vaccinated for VZV. Should I avoid contact with them while I have shingles?
- How long will I be contagious?
- Can I go to work while I have shingles?
- What are my treatment options?
- When can I expect the rash to go away? Will it leave scars?
- Will the pain I am experiencing subside after the shingles goes away?
- How likely am I to have additional outbreaks?
- Should I receive a booster shot for VZV?