Shingles, or herpes zoster, is a condition caused by the reactivation of the varicella zoster virus (VZV). This condition causes a characteristic skin rash. It is thought to occur due to the failure of the immune system to control the dormancy or latency of the virus. When VZV infection first occurs, it results in chickenpox. Once the illness resolves, the VZV becomes dormant in the body and reactivates later to cause shingles.
Although shingles is more common among those with a weakened immune system, there are many patients with shingles who have a normal immune system. In these cases, it is thought to be due to decreased levels of VZV antibodies to the point where it is no longer effective in the prevention of shingles. This hypothesis can be supported by the observation that pediatricians seldom develop shingles as they are routinely reexposed to VZV.
Shingles is caused by the VZV. Most individuals are infected in their childhood resulting in an episode of chickenpox. The virus is then eliminated from most locations by the body’s immune system. However, it remains dormant in the body and becomes reactivated at a later point in life to cause shingles. This means that shingles can only occur in those who have been previously infected with VZV. While it mostly affects those above the age of 50, it can occur to individuals of all ages. Repeated episodes of shingles are rare. It usually affects those who have a compromised immune system such as those with psychological stress, aging, or are on immunosuppressive therapy; it can also occur in normal individuals. Like chickenpox, direct contact can result in transmission. The newly infected person will develop chickenpox.