Shingles is a Viral Infection that is caused by Varicella Zoster Virus

Shingles is a viral infection that is caused by Varicella zoster virus. It is characterized by a painful lesions (vesicles) and a rash along the distribution of a nerve or nerves, and occurs due to reactivation of the virus that has lain dormant in the body since a childhood attack of chicken pox. It is a fairly common condition and is easily treatable.

In this article, we shall look into this condition a bit further, and discuss the diagnosis and management of shingles.

Epidemiology

Shingles can be seen in any age group but is commoner in older patients due to their reducing levels of immunity. Studies have shown that over 99.5% of adults over the age of 40 in the United States are at risk of developing a reactivation of the virus and subsequent shingles.1

Cause

Shingles is a reactivation of childhood chicken pox that is caused by the Varicella
zoster
virus. The Varicella zoster virus is a Herpes virus that is spread through direct contact with mucus membranes.

Once it enters the body, it travels up the nerve fibers to their respective ganglion where it can lay dormant for many years. It is unclear why exactly it manifests suddenly after many years, and some theories support the reduction in body immunity as a cause.

The virus can not only lay dormant in the nerves supplying the skin, but can also spread to the brain as well. This can cause a lot more serious infections. Rarer cases have involved the eye which is potentially life threatening.

Clinical features

Shingles usually manifests in different stages during its pathogenesis. Most cases being with a feeling of being generally unwell, along with altered skin sensation at the site of impending lesions. Patients can also suffer from a headache and sometimes fever. This stage is called the ‘prodromal’ stage.

Following the prodromal stage, patients start to notice skin eruptions. These start as small red flat lesions called macules, which can then develop into papules and vesicles (small fluid filled lesions). These can sometimes join together and become larger vesicles called bullae.

The distribution of these lesions is characteristically along a dermatome – referring to nerve supply to the skin. The lesions are painful and can cause the patient a great amount of distress along with sleepless nights. This phase of the illness is called the ‘eruptive’ phase.

Shingles eruptions seen along the distribution of the
thoracic nerves.

The eruptive phase usually lasts up to a fortnight, and patients remain infective until the vesicles start to dry up and form a crust. Most cases resolve right here, but sometimes complications can occur, which have been discussed later.

Diagnosis

In most cases, a diagnosis is made from history and clinical examination. The appearance and distribution of the lesions along with the pain is characteristic and is easily identified by an experienced physician. While specific tests are usually not necessary, they may be required if the patient were to suffer from complications of shingles.

1. Tzanck smear – Here, the lesions are gently scraped, stained with Giemsa stain and examined under a microscope. Characteristic giant cells with multiple nuclei are seen in cases of shingles. However, this test, while simple, does not differentiate between different kinds of Herpes viruses.

2. Direct immuno-fluorescence – While this test is a lot more specific and sensitive, it is also more expensive and is not always performed.

Other tests include a blood culture or a biopsy, but these are generally not performed as the results can take a few days to return.

Treatment

Most cases of shingles resolve themselves in around 10 to 15 days. However, treatments can be offered which will help speed recovery and reduce pain. In addition, these treatments can help prevent complications of shingles as well.

1. Pain relief

The pain usually does no resolve with over the counter medication, and can require opioids and antic-convulsant medication such as gabapentin. Antiviral treatments to get rid of the virus are also useful in reducing pain.

2. Antiviral treatment

Acyclovir is the preferred anti-viral agent and is usually administered orally. It acts by inhibiting the viral DNA replication process. However, in more severe cases, intravenous Acyclovir may need to be prescribed. The primary aims of using antiviral treatment are to inhibit viral growth, reduce pain and to allow for healing of the vesicles.

Other agents used are Valacyclovir and Famciclovir.

3. Steroids

These were used often in the past, but its benefit with concurrent use of an anti-viral agent is still doubtful.

Complications

Patients with shingles can develop certain complications, some of which can be life-threatening. These complications are often seen in individuals who have low immunity, and if recognised early require immediate treatment.

1. Post herpetic neuralgia – This refers to persistent pain despite the infection subsiding and treatment course being completed. Treatment requires powerful pain medications such as tricyclic antidepressants, opioid analgesics and anticonvulsant agents such as gabapentin. Steroid injections may be helpful.

2. Herpes zoster ophthalmicus – This refers to shingles that involves the eye, and is a serious condition. High dose oral anti-viral therapy should be commenced urgently. Steroids may be useful in reducing the pain.

Herpes zoster Ophthalmicus

Prevention

We all know that prevention is better than cure. As reactivation of the Varicella zoster virus is what leads to shingles, steps should be taken to prevent this. Recently, vaccines have been developed to prevent Varicella infection in childhood. Also, ensuring no contact with patients or family members with shingles during the cute phase can help prevent one from picking it up.

Recently, the FDA approved a drug called Zovastax2 that can effectively reduce the chances of developing shingles.

References

1. Marin M, Meissner HC, Seward JF. Varicella prevention in the United States: a review of successes and challenges. Pediatrics. Sep 2008;122(3):e744-51.

2. Schmader K, Levin M, Gnann J, McNeil S, Vesikari T, et al. Efficacy, immunogenicity, safety, and tolerability of zoster vaccine (ZV) in subjects 50 to 59 years of age (Poster/Abstract). Infectious Diseases Society of America. The 48th Annual Meeting of the Infectious Diseases Society of America. 10-21-2010;Vancouver, British Columbia, Canada:Ref Type: Abstract: 3363.