Shingles (Herpes Zoster) - Cause

What is shingles and how common is it?

Shingles is an infection of a nerve and the area of skin supplied by the nerve. It is caused by a virus called the varicella-zoster virus. It is the same virus that causes chickenpox. Anyone who has had chickenpox in the past may develop shingles. Shingles is sometimes called herpes zoster. (Note: this is very different to genital herpes which is caused by a different virus called herpes simplex.)

About 1 in 4 people have shingles at some time in their lives. It can occur at any age but it is most common in people over the age of 50 years. After the age of 50, it becomes increasingly more common as you get older. It is uncommon to have shingles more than once but some people do have it more than once.

How does shingles occur?

Most people have chickenpox at some stage (usually as a child). The virus does not completely go after you have chickenpox. Some virus particles remain inactive in the nerve roots next to your spinal cord. They do no harm there and cause no symptoms. For reasons that are not clear, the virus may begin to multiply again (reactivate). This is often years later. The reactivated virus travels along the nerve to the skin to cause shingles.

In most cases, an episode of shingles occurs for no apparent reason. Sometimes a period of stress or illness seems to trigger it. A slight ageing of the immune system may account for it being more common in older people. (The immune system keeps the virus inactive and prevents it from multiplying. A slight weakening of the immune system in older people may account for the virus reactivating and multiplying to cause shingles.)

Shingles is also more common in people with a poor immune system (immunosuppression). For example, shingles commonly occurs in younger people who have HIV/AIDS or whose immune system is suppressed with treatment such as steroids or chemotherapy.

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Author:
Dr Mary Harding
Peer Reviewer:
Prof Cathy Jackson
Document ID:
4328 (v48)
Last Checked:
20 June 2016
Next Review:
20 June 2019

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.