Shingles and Chickenpox (Varicella-Zoster Virus) - Introduction

Introduction

Shingles and chickenpox were once considered separate disorders. Researchers now know that they are both caused by a single virus of the herpes family known as varicella-zoster virus (VZV). The word herpes is derived from the Greek word "herpein," which means "to creep," a reference to a characteristic pattern of skin eruptions. VZV is still referred to by separate terms:

• Varicella: The primary infection that causes chickenpox
• Herpes zoster: The reactivation of the virus that causes shingles

Varicella (Chickenpox). When patients with chickenpox cough or sneeze, they expel tiny droplets that carry the virus. If a person who has never had chickenpox or been vaccinated inhales these particles, the virus enters the lungs. From here it passes into the bloodstream. When it is carried to the skin it produces the typical rash of chickenpox.

Herpes Zoster (Shingles). The varicella virus also travels to nerve cells called dorsal root ganglia. These are bundles of nerves that transmit sensory information from the skin to the brain. Here, the virus can hide from the immune system for years, often for a lifetime. This inactivity is called latency.

Click the icon to see an image of shingles.

If the virus becomes active after being latent, it causes the disorder known as shingles. The virus in this later form is referred to as herpes zoster. The virus spreads in the ganglion and to the nerves connecting to it. Nerves most often affected are those in the face or the trunk. The virus can also spread to the spinal cord and into the bloodstream. In 2006, scientists at the U.S. Institutes of National Health identified a specific protein, called insulin-degrading enzyme, which causes the varicella-zoster virus to spread throughout cells in the body. The scientists hope that this discovery may eventually help in developing new drug therapies for treating shingles.