The shingles virus

What is it?
Many people know that there is a connection between shingles and chickenpox. The virus responsible is one of the herpesvirus group, and is known as the varicella-zoster virus (VZV).

When this virus first infects you, usually during early childhood, it causes the characteristic chickenpox rash of small fluid-filled blisters (vesicles) scattered over the body. The vesicles are produced by virus particles entering the skin cells, where they divide and destroy the cells.

The virus then remains in the body hidden away in nerve cells in the spinal cord for the remainder of your life. After a variable period of time, usually several years, the virus reactivates and begins to divide again. This time it travels along nerve fibres to different parts of the skin to cause shingles.

What wakes the virus up?
It is not clear what makes the virus reactivate in otherwise healthy people. A temporary weakness in immunity (the body's defence against infection) may allow the virus to multiply, and in fact attacks seem to occur at times of stress or after serious illnesses.
If the immune system is compromised for other reasons, shingles can occur more readily, such as after a transplant operation, if you are taking immune suppressant medication, and with AIDS. Sometimes the shingles takes a nastier form in these cases.

What are the symptoms?
The first symptom of shingles is a burning sensation, tingling or extreme sensitivity in the area of skin supplied by the infected nerve. This may be present for up to three days before the rash comes out. You may also develop a headache and high temperature.

The skin then becomes red, and soon groups of blisters appear resembling chickenpox. The blisters travel along the path of the nerve around the body, most commonly around the trunk but also on the face, arms and legs.

This is the feature of shingles that its name was derived from, the Latin word 'cingulum' meaning a belt. The blisters can last for up to three weeks. The fluid in the blisters commonly becomes bloodstained. The blisters finally crust over and the scabs fall off.

How is it diagnosed?
The diagnosis is based on the typical story and the appearance and position of the blisters. If there is any doubt, scrapings from the base of the blisters can be sent to a laboratory to be analysed. The majority of people with shingles are otherwise fit and healthy, but if you think you may be at risk from HIV you should talk to your doctor who can test you if needed. Shingles in younger people has been linked to the diagnosis of AIDS and other diseases such as leukaemia.

What are the complications?

• Occasionally there is facial paralysis if the facial nerve is involved but this is not commonly permanent.
• Scarring can occur after a severe infection, particularly if there has been bacterial infection as well.
• Great care is needed if the area of the face around the eye is involved, because ophthalmic shingles can cause severe inflammation of the cornea. This can lead to permanent loss of sight and so hospital admission for intensive therapy is necessary for this type of shingles.
• Sometimes bacterial infection of the blisters can occur, which delays healing, and antibiotics are prescribed to treat this.
• The most important complication is called post-herpetic neuralgia. This is more likely the older you are and is difficult to treat. The pain commonly lasts for up to three months after an attack but can be severe and long lasting.