Understanding Shingles

Herpes zoster, commonly known as shingles, is a reactivation of the varicella zoster virus.  This viral infection may sound foreign, but it is actually the virus that causes chickenpox, the bane of everyone’s childhood.  Shingles in essence is a reoccurrence of this original chickenpox, but at a later time. But why or how does this happen?  Following the resolution of chickenpox, the varicella zoster virus lies dormant in the spinal dorsal root ganglia, or the spinal cord nerves until something triggers a reactivation is triggered.  This is important as 95% of adults have antibodies to varicella zoster virus and all those individuals are vulnerable to reactivation of infection.


Triggering a reactivation is usually due to a decrease in cellular immunity.  This can occur as we age, are subjected to stress, or occur by the body’s exposure to syndromes and medications that result in decreased immunity.  These syndromes and medications include HIV and chemotherapy. Shingles is characterized by painful vesicular rash, featuring small blisters on the skin.  This rash is usually restricted to a unilateral dermatome distribution, or in simple terms one horizontal band around the torso.   A dermatome is a band of the body that relates back to early development.  Each dermatome is supplied by a single spinal nerve.  As such, the nerve that experiences the reactivation of chickenpox is going to dictate the segment of the body that is affected and breaks out in pox-like rash.  Shingles usually has a benign course, but in rare cases the infection can spread.  For these rare individuals, particularly those who are immunosuppressed, where the infection spreads a severe systemic illness can be the end result.

Shingles occurs in several phases.  These are the main phases of shingles:

Pre-eruptive phase:

·         Characterized by unusual skin sensation or pain within the affected dermatome

·         Blisters or lesions start to appear on the set dermatome between 48-72 hours

·         Pain is generally nondescript at this time, and can be mistaken for other conditions from musculoskeletal issues to heart problems.

·         Other symptoms you might experience:

o   Muscle aches

o   Headache

o   Photophobia

o   Rarely, fever

Acute eruptive phase:

·         Emergence of vesicular eruptions, or what looks like blistering on top of red irritated skin

·         During this phase the skin blisters will rupture and eventually crust over becoming dry and flaky

·         In this phase most adults experience pain and discomfort

·         Until all blisters have dried over, those with shingles are contagious and can spread the varicella virus.

o   Should avoid people who have not had chickenpox, pregnant women and the immunosuppressed

o   Also avoiding young children that have not been vaccinated

·         Tends to resolve within 2 weeks but can sometimes take up to a month

Chronic phase (post herpetic neuralgia):

·         The most common complication

·         Characterized as persistent or recurring pain in the affected area

·         Most people report a deep burning or aching pain, or electric shock–like pains.

·         Resolution of the pain may require an extended period of time.

·         Pain lasting longer than 12 months has been described in about half of people who get shingles older than 70 years