Causes

Chickenpox

Anyone who has not had chickenpox or the vaccine, is at risk for contracting the virus if exposed to someone with either chickenpox or shingles. The time between exposure to the virus and appearance of symptoms (called an incubation period) is between 10 and 20 days. The virus is spread through sneezing, coughing, and breathing – in other words, when someone with chickenpox sneezes or coughs, there are respiratory droplets with the VZV virus in the air. Then, you can breathe in those infected droplets and, if you have never had chickenpox or the vaccine, get chickenpox yourself.

Another possible way to get chickenpox, is to come into direct or indirect (like the clothes of someone with shingles) contact with discharge from VZV skin lesions.

The virus is contagious from two days before the rash appears until all of the lesions have crusted over.

Shingles

While shingles is caused by the same virus that leads to chickenpox, the way that you develop this painful skin lesion is quite different. After you have had chickenpox, the virus lives in a dormant state (like it is hibernating) in nerve cells along the spine. Later in life, when it is reactivated (usually from a weakened immune system, aging, or other risk factor), the virus travels down the tract of the particular nerve where it was "hibernating", first causing the pain and other sensations followed by the rash. The pattern or path that the symptoms follow is called a dermatome, which essentially means the area of the skin that the nerve supplies.

Causes of Shingles (Herpes Zoster)
Herpes Zoster virus
Weak immune system
Stress
Vitamin and mineral deficiency