Shingles or Herpes zoster is a viral disease that occurs with reactivation of the varicella-zoster virus (a virus that causes varicella or chickenpox). It is characterized by a painful skin rash which usually shows a dermatomal distribution.

Pathophysiology of Herpes Zoster

Varicella-zoster virus (VZV), is a double-stranded DNA virus. It is a herpes virus related to the herpes simplex virus. It causes varicella or chickenpox which is a contagious disease and presents with fever and skin lesions. Mostly chickenpox affects people during childhood.

After the acute infection resolves, the virus stays in the ganglia adjacent to the spinal cord (dorsal root ganglion) or other sensory ganglia in a dormant form for years and decades. It is never eliminated from the body by the immune system. However, the immune system of the host does not allow the virus to replicate.

When the host’s immune system is suppressed (either due to emotional or physical stress or due to severe immunosuppression), the virus may get reactivated resulting in clinical manifestation of herpes zoster.

Some people will apparently normal immunity also tend to develop shingles. In these patients, the disease is thought to occur when VZV antibody titers and cellular immunity are reduced to such low levels that they are no longer effective in preventing viral activation.

Signs and Symptoms of Shingles

Clinical features can be divided into the following phases: Pre-eruptive phase (pre herpetic neuralgia)

Acute eruptive phase

Phase of resolution

Chronic phase (postherpetic neuralgia)

Pre-eruptive Phase

2- 4 days before the rash appears, symptoms such as pain, itching, tingling or other abnormal sensation may occur at the site of eruption.

The patient may also have other symptoms, such as body aches, headache, photophobia, or even fever.

This prodromal phase is associated with the spread of varicella-zoster virus particles along the sensory nerves. About one-tenth of patients, however, do not experience a prodromal phase and present with simultaneous onset of pain and rash.

Acute Eruptive Phase

The affected area shows patchy erythema, along with induration.

Herpetiform vesicles which are grouped together develop on this erythematous base. These vesicles usually occur in a single, wide stripe involving one side of the body corresponding to the affected dermatome. This is the classic finding of herpes zoster.

Pain at the affected site is usually present. It may be severe in some cases. Some individuals experience severe pain without a vesicular eruption (ie, zoster sine herpete).

Phase of Resolution

Initially, the vesicles are filled with clear fluid but later they may become cloudy. They could also rupture, get covered by a crust and finally involute.

Once involution of the vesicles starts, the underlying erythematous base also starts resolving.

In the majority of the cases, the skin lesions heal completely, leaving no visible scar. In a few cases, however, the skin may show scarring if deep layers of epidermis and dermis had been involved by excoriation or if there is a secondary bacterial infection.

Symptoms usually resolve over 10-15 days. However, complete healing of the skin lesions may take up to a month.

Chronic Phase

Post Herpetic Neuralgia (PNH)

In some cases, pain may persist or recur after the acute phase is over and all the skin lesions have healed. This pain is restricted to the area of original dermatomal involvement.

It can be extremely severe and can persist for many days or even years.

It occurs due to peripheral nerve damage or continued viral activity.

Elderly and debilitated patients have a higher chance of experiencing postherpetic neuralgia. Also, patients who have severe prodromal pain and have a large number of vesicles during the eruptive phase tend to have higher chances of post-herpetic neuralgia Chronic persistent pain also tends to occur more often in patients of herpes zoster ophthalmicus (HZO) or in those having upper-body dermatomal involvement.

Other features of chronic phase may include hyperesthesia or rarely, hypoesthesia or anesthesia in the area involved.

3 days old Shingles rash on armpit copyright: medcaretips.com

Other Areas of Involvement of Herpes Zoster

Herpes Zoster Ophthalmicus (HZO)

It occurs when the ophthalmic division of cranial nerve V or the trigeminal nerve is involved in viral reactivation. The area around the eye shows classic skin lesions of shingles. Eye symptoms may include severe pain in the eye, conjunctivitis, keratitis, uveitis, and optic nerve palsies. If early detection and adequate treatment is not given, there can be a risk to vision.

Herpes Zoster Oticus or Ramsay Hunt Syndrome Type II.

It occurs due to the spread of the virus from the facial nerve to the vestibulocochlear nerve. It involves the ear resulting in hearing loss and vertigo. Skin lesions may or may not occur.

Herpes Zoster of Mouth

Shingles may occur in the mouth if the maxillary or mandibular division of the trigeminal nerve is affected, Mucous membrane of the upper or lower jaw may be affected. The skin supplied by the same trigeminal nerve may show typical skin lesions. Oral shingles may lead to some unusual complications that are not seen elsewhere. Since the blood vessels are closely related to nerves, the virus can involve the blood vessels. This can compromise the blood supply causing ischemic necrosis resulting in rare complications such as osteonecrosis, pulp necrosis, periodontitis or tooth loss.

Herpes Zoster Encephalomyelitis

Herpes zoster can also cause inflammation of the brain and meninges. It can also cause inflammation of the spinal cord (transverse myelitis), cranial nerve palsies, and granulomatous angiitis.

Disseminated Herpes Zoster

Disseminated or widespread shingles may occur in patients who are immuno-compromised. In this, numerous skin lesions (usually more than twenty) occur. These lesions may occur either distant to the primarily affected dermatome or may be directly adjacent to it. Organ involvement including the brain or liver may be involved. It can be a life-threatening condition.

Unilateral Herpes Zoster involving Multiple Dermatomes

Multiple dermatomal involvement on one side of the body is rare. It is seen in severe immuno-compromised individuals. Involvement of 2 dermatomes is called zoster duplex, and involvement of 3 or more is called zoster multiplex.

Recurrent Herpes Zoster

Herpes zoster can rarely recur. Old age and pain persisting for more than 30 days are risk factors for recurrences.

Herpes Zoster Involving Other Organs

The virus can also affect other organs including urinary bladder, bronchi, pleural spaces, gastrointestinal tract, etc.

Complications of Shingles

Mostly signs and symptoms of shingles resolve without leaving any sequel. In a few cases, the disease may lead to complications. Complications are more often seen in patients who are immunocompromised.

Secondary bacterial infection at the site of the rash. It can even cause necrotizing fasciitis – a lethal condition.

Postherpetic neuralgia (PHN), affecting 10 to 20 percent of people with shingles. In older patients, nearly half of the patients may suffer chronic persistent pain.

Peripheral motor neuropathy occurs in 5 to 10 percent of cases

Guillain-Barré syndrome is a rare complication which occurs due to reactivation of latent VZV.

Is Shingles Contagious?

Shingles is not contagious because the disease is caused by the reactivation of a virus already present in the body.

A person suffering from shingles cannot transmit shingles to another person who comes in contact with him.

However, a person suffering from shingles can transmit the virus to another person who has never had exposure to chickenpox. So patients suffering from shingles should avoid contact with children who have never had chickenpox or have not been vaccinated against chickenpox.

They should also avoid contact with people who are immunocompromised like HIV patients, patients who have undergone transplant, etc.

Basic hygienic measures like washing of hands after touching the skin rash and keeping the rash covered should be adopted so that others do not come in contact with it.

Differential Diagnosis

Herpes simplex infection: Lesions of herpes zoster can mimic herpes simplex infection. The point of differentiation is that herpes simplex usually does not show a dermatomal distribution and has a greater tendency to recur.

Shingles can also be confused with a variety of other skin conditions including acneform eruptions, contact dermatitis, folliculitis, dermatitis herpetiformis, impetigo, ecthyma, erysipelas, insect bite, etc.

Investigations

Herpes zoster is usually diagnosed clinically by history and classic features. Characteristic rash or pain, limited to a dermatome is suggestive of shingles. Lab investigations are not required in most of the cases.

If the diagnosis is equivocal, like in the case of immunocompromised patients (when classic signs and symptoms are not present), further testing may be carried out.

Tzanck smear

It is a cost-effective and simple laboratory test. The base of a fresh vesicular lesion is scraped off after unroofing the lesion. The material thus collected is spread on a glass slide, stained with suitable dyes and studied under a microscope. Detection of multinucleated giant cells indicates herpes infection. The test, however, cannot differentiate between VZV and other herpes viruses like herpes simplex virus. Also, the test has very low sensitivity and specificity.

Direct Fluorescent Antibody (DFA) Test

Fluid from a vesicle or corneal lesion can be used to detect antibodies against the virus.

Polymerase Chain Reaction (PCR)

Fluid from the vesicle of skin lesion, a corneal lesion, or blood may be used to detect VZV nucleic acid.

Both DFA and PCR testing are more sensitive and specific as compared to Tzanck testing and also allow differentiation between herpes zoster and herpes simplex virus infection.

Treatment

Shingles is mostly a self-limited disease and usually resolves without any intervention.

Treatment, if given, is symptomatic. Early treatment can reduce pain, help the rash to heal quickly, and prevent complications like secondary bacterial infections and scarring.

Anti-inflammatory drugs like NSAIDs help to reduce inflammation and pain.

Corticosteroids may have to be given for very severe pain.

Local anesthetics like lidocaine numb the area where they are applied and provide relief from severe pain.

Anti-histaminic drugs help to relieve itching.

Anti-viral drugs like acyclovir, famciclovir or valacyclovir reduce the progression of shingles disease, especially if given within 3 days of the appearance of symptoms.

Antidepressant drugs like amitriptyline and nortriptyline are also found to be useful in reducing pain as well as in controlling the symptoms of PHN. However, these drugs can take a long time – from days to months to produce their effect.

Certain anticonvulsant drugs like gabapentin and pregabalin also found useful in relieving nerve pain associated with shingles.

Home Remedies and Self Care Tips for Shingles

Besides medical treatment, the following steps taken by the patient at home can help to relieve the symptoms.

• Regular bath

Regular bathing and cleaning of the skin blisters with cool water produces a soothing effect and helps to ease the pain. Colloidal oatmeal or cornstarch can be added to lukewarm bathwater. However hot water should not be used as it causes an increase in local blood flow and can worsen the blisters of shingles.

• Using a wet cool compress on the affected skin to reduce pain. However, ice packs should not be used as they can worsen the pain.

• Applying calamine lotion to the skin lesions

• Applying a paste of cornstarch or baking soda and water on the rash several times a day helps to relieve itching.

• Eating a healthy diet

Low immunity can worsen shingles promoting its spread to other parts of the body. Therefore make sure to eat a balanced and healthy diet consisting of whole-grain products, fruits, vegetables , dairy products, fish, meat, etc. Foods rich in saturated fats, refined carbohydrates, and sugary drinks should be avoided as they reduce the body’s immunity.

• Wearing loose-fitting clothing preferably made of cotton which does not irritate the skin.

• Avoiding scratching the rashes as it can cause infection and permanent scarring.

It must be kept in mind that once a person gets shingles, there is no cure. The disease has to run its course. Medical treatment and home remedies only provide relief from pain and itching and help to reduce the severity of the disease.

Vaccine for Shingles

A vaccine against shingles is available which reduces the risk of developing shingles. Also, it reduces the chances of long-term complications, such as PHN. People who have already had shingles can have the vaccine to prevent future occurrences. 2 vaccines have been approved against shingles by The U.S. Food and Drug Administration (FDA). These are

Zostavax vaccine

It is a live-attenuated vaccine and is given as a single dose. It is an older vaccine.

Shingrix vaccine

It is a recombinant vaccine. It is a newer vaccine and is given in two doses at an interval of 6 months. Shingrix vaccine produces a longer-lasting effect, is more effective and is hence preferred over zostavax vaccine.

It is recommended that people over 50 years of age should get a vaccination against shingles.

Prognosis

Shingles usually resolves within 2 to 4 weeks. Most immunocompetent, young and healthy people recover fully without any permanent sequele or complications. Less than 4% of shingles patients need to be hospitalized for treatment of complications. Most of the people who develop complications are immunocompromised. Shingles rarely lead to the death of the patient. Immunocompromised and older patients are more prone to such fatal consequences.