Shingles is a very common condition that can be a real pain – both figuratively and literally. While most of you would have heard of shingles, many of you would be unaware that the story of shingles begins with chickenpox.

Chickenpox

Chickenpox is a viral infection caused by the varicella zoster virus. It is predominantly a disease of childhood, although in tropical countries – like Sri Lanka – more people reach adulthood without getting infected. Chickenpox causes a horrible rash all over the body that appears in crops. The rash starts off as red dots that progress to clear blisters, then pus-filled lumps and finally dry crusts. And it’s not just the skin that is affected. Chickenpox can affect any part of the body.

But here’s the thing about chickenpox that is pivotal to understanding shingles: when people recover from chickenpox, the chickenpox virus does NOT leave the body. It goes into hibernation in our nerve roots. The chickenpox virus lives with us forever. And it is the chickenpox virus that causes shingles.

Shingles – a painful rash

For most of our lives, the chickenpox virus will live quietly in our nerve roots without making a fuss – just like a dormant volcano. But suddenly, one day it will erupt, causing shingles. There may be no obvious precipitant to shingles but we know that it is more common in people over 50 and in those with low immune systems. Like chickenpox, shingles causes a blistering rash. But that’s about where the similarity ends. The cardinal features of shingles are that it is:

Extremely painful (the pain usually precedes the rash)
Only on one side of the body
Very localized e.g. on the arm, face, chest, or tummy

Of course, there are exceptions to every rule and shingles has been documented to occur without the rash and in more than one part of the body – but that’s pretty uncommon.

Why you should worry about shingles: PHN

Shingles can cause a number of complications ranging from meningitis to weakness and visual problems. But the most feared complication of shingles is long-term pain called post-herpetic neuralgia or PHN. This refers to pain persisting for more than three months after shingles appears. PHN is not due to infection – the infection has well and truly gone. PHN can be so bad that people become invalids: they are unable to live a normal life due to agonizing pain. Some people become dependent on morphine while others need surgical procedures or epidural drips. And PHN isn’t uncommon: 50% of older adults who get shingles will go on to develop PHN.

How to reduce the chance of getting PHN

There are two ways:

Antiviral tablets – If someone with shingles starts taking antiviral tablets WITHIN 3 DAYS OF THE RASH APPEARING, this reduces the chances of PHN developing. This is the ‘Three-day Deadline’. If the tablets are started beyond those three days, then you’ve missed the boat. There are three types of antiviral tablets to combat shingles: aciclovir, famciclovir and valaciclovir. So if you think you have shingles, see your doctor as soon as possible to start on one of these tablets.

Vaccination – A vaccine now exists to prevent shingles. Countries like the USA and Australia recommended the vaccine for people aged 60 and over

(http://www.health.gov.au/internet/immunise/publishing.nsf/Content/Handbook-zoster, http://www.cdc.gov/vaccines/vpd-vac/shingles/vacc-need-know.htm).

The vaccine is well tolerated. The only issue is that the vaccine contains live virus; therefore, people with low immune systems should avoid it.

So in conclusion, shingles is a one-sided painful rash that is caused by reactivation of the chickenpox virus. PHN is a chronic pain syndrome following shingles that can be utterly disabling to its sufferers. People aged 60 and over can receive a vaccine to prevent getting shingles. But if you do get shingles and start antiviral tablets within three days of the rash appearing, then you’ll reduce your chances of getting PHN.

(The writer is an Associate Professor of Medicine at the Australian National University and a Senior Specialist in Infectious Diseases)

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