You might also know varicella-zoster virus as: varicella (this is the primary infection that leads to chickenpox) and herpes zoster (this is the reactivation of the virus that leads to shingles).

Chickenpox is spread by cough, sneeze or spit. These organ materials contain the virus if one person is infected and will get into contact by air with a healthy person. The virus will enter the lungs and than pass into the blood stream. After a few days the signs of chickenpox will appear on the skin.

The virus can also go inside nerve cells that are specialized in transmitting information from the skin to the brain. If the virus shelters in these cells, there can pass a few years until it will reactivate, and cause shingles. The virus that is hidden and is inactive (latent) is also known as herpes zoster. The virus affects ganglions and nerves. The virus will mostly spread into the face and trunk nerves; it rarely goes into the spinal cord or blood stream.

Many people ask themselves why some develop shingles and why others do not even if all have suffered from chickenpox when being younger. Doctors suspect that the virus reactivates in some people because they might suffer of other diseases which weaken the immune system, like AIDS, cancer, diabetes or take drugs that suppress the immune system. Adults are most likely to develop shingles but not only them. Children are also exposed to shingles. Only those who have a good immune system response and those who have been vaccinated against these two diseases are at a safe place.

The herpes family includes six viruses which can affect humans. These viruses look quite alike, and are all reproducing within the structure of a cell. These viruses are: Herpes Simplex virus, Cytomegalovirus, Epstein-Barre virus (responsible for mononucleosis), Varicella-Zoster virus, Human Herpesvirus type 6 (responsible for roseola), and Human Herpesvirus type 7.

All these human viruses can shed inside the organism and stay there in a latent form for many years and reactivate when the immune system does not respond well any more.