Shingles: Pathophysiology, Definition, Incidence

Shingles: Pathophysiology, definition, incidence

Shingles is a skin rash characterised by pain and blistering. Shingles is also known as ‘herpes zoster’. Shingles can affect any part of the body, including the face. The rash is made up of tiny blister-like spots that hold fluid. Shingles occurs because of a reactivation of the chickenpox virus, which remains in the nerve cells of the body after an attack of chickenpox.
Shingles can be spread when a person comes into contact with fluid contained in the blisters (however, the person would ‘catch’ chickenpox, not shingles). Anti-viral medications work best if administered within three days, and preferably 24 hours, of the onset of a rash.


Shingles is a ‘reactivated’ chickenpox virus

Anyone who has had chickenpox can develop shingles. However, only people who have never had chickenpox can catch the virus from another person with shingles. A person who has never had chickenpox, but comes into contact with the shingles virus, will develop chickenpox (not shingles).
The virus responsible for shingles can be spread by direct contact with the lesions or by touching any dressings, sheets or clothes soiled with discharge from the spots. Anti-viral medications work best if administered within 24 hours of the onset of a shingles rash.


The virus travels down nerves
The rash caused by shingles usually takes the shape of a ‘belt’ or band around or across the body. The rash forms its characteristic pattern because the virus works down the nerves that branch out from the spinal cord and encircle the body. The chest and stomach are most commonly affected.
Tender, painful skin signals the beginning of an attack. The skin then turns red and breaks out in blisters. The rash can last for a few days or weeks. During that time, a scaly crust might appear. Once the attack is over, the skin usually returns to normal but there can be some scarring in severe cases.


The link to chickenpox
Shingles is caused by the Varicella zoster virus, which is also responsible for chickenpox. People who contract chickenpox are at risk of developing shingles later in life, since the virus lies dormant in the body (in one or more dorsal root ganglia). Fortunately, it is rare to have more than one attack of shingles.


Post-herpetic neuralgia

Sometimes the pain doesn’t go away once the shingles rash has cleared. This complication is called post-herpetic neuralgia and is more common when the shingles rash appeared on the face rather than the body. This type of shingles rash tends to affect the skin around the eye and occasionally the eye itself.


Type of help available
Anti-viral medications can help ease the pain and shorten an attack of shingles. The medication works best if administered within three days, and ideally within 24 hours, of the onset of a rash. Analgesic medication may also ease post-herpetic neuralgia, but consult your doctor first.

 

          Most common between the ages of 50 and 70

          Most people who develop herpes zoster recover within 2-6 weeks

          Up to half of all affected people over the age of 50 develop post-herpetic neuralgia

          A single attack of herpes does not provide immunity, and the infection may recur


Herpes zoster is estimated to affect 20 per cent of the population, particularly the elderly. In the USA there are estimated to be 500,000 cases of herpes zoster infections per year, resulting in 1.5 million visits to physicians.  Data on shingles in Australia are limited. Data for 1999/00 indicate that there were 1,918 admissions to Australian hospitals for herpes zoster.  These were composed of 776 zoster infections without complications and 1,142 infections with complications. The most common complication was nervous system involvement other than encephalitis and meningitis, which included polyneuropathy, trigeminal neuralgia and geniculate ganglionitis.  Recent evidence suggests that adults with contacts with children and therefore with chickenpox have a lowered risk of developing zoster infections. This protective effect is greatest in those adults with many social contacts with children outside the home including contacts with sick children.

 

Resources:

http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Shingles?open

http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Shingles_Q&As?OpenDocument

http://www.health.gov.au/internet/main/Publishing.nsf/Content/cda-pubs-cdi-2002-cdi2604-htm-cdi2604o.htm

The Royal Australian College of General Practitioners: Complete Home Medical Guide, 2nd Ed [2006], p. 290-291

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~ by pcl4 on August 18, 2008.

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