Have you had chickenpox before? If yes, then you carry the Herpes Zoster virus. Not to worry, though; you won't develop cold sores or genital herpes lesions. Those are caused by a different virus (though part of the same herpes virus family). The Herpes Zoster virus is a reactivated form of the Varicella-Zoster virus (VZV), responsible for causing both chickenpox and shingles.
How Could One Virus Cause Two Different Illnesses?
It's an interesting phenomenon, for sure. While the exact mechanism is unclear, the basis of it lies with the virus's ability to become latent. It does this by entering nerve cells of the dorsal root ganglia, bundles of nerves that allow the skin to communicate with the brain.
Because the immune system doesn't patrol the nervous system, the virus can hide out indefinitely in these cells. You may have heard that you can never get chickenpox more than once; and that's usually true. You can rarely become infected with chickenpox a second time for a couple reasons.
First, VZV mutates very slowly and therefore is easily recognized by the immune system upon exposure with the same virus.
Second, if the Varicella-Zoster virus becomes re-activated it can only become Herpes Zoster, which causes shingles and not chickenpox.
What Causes Herpes Zoster to Come Out of Latency?
This also is poorly understood; most explanations have something to do with the immune system. Shingles most commonly occurs when the immune system has become compromised for some reason: medications, stress, aging, or immunodeficient diseases. How the virus knows when the immune system is impaired is something that will likely take many years to discover.
So what is it Like Having Shingles?
As mentioned earlier, the Herpes Zoster virus travels down the nerve bundles of the dorsal root ganglia when it becomes reactivated. This causes nerve damage, resulting in sensory loss, pain, and other neurological symptoms. Virus particles will also often invade the surrounding skin, resulting in a painful rash composed of red, fluid-filled blisters. If the virus somehow invades the neurons of motor nerves (as opposed to sensory nerves) the muscles controlled by them can become weak. The immune system will eventually detect the virus as it wanders out of nerve cells and essentially beats the virus back into latency.
Is Herpes Zoster Contagious?
Not really; the Varicella-Zoster Virus (the virus which causes both chickenpox and shingles, remember) can infect anyone who has never before encountered it. This means that if someone who has never had chickenpox comes in contact with the blisters of a shingles rash, they could develop chickenpox, but not shingles.
Shingles will only develop when the latent VZV becomes re-activated. Chickenpox, however, is extremely contagious to those who have never experienced it and can be spread by airborne transmission (coughing, sneezing) or by touching pox of the chickenpox rash. The chickenpox illness is much less severe in children, which is part of the reason mothers try very hard to infect their children while they are young.
Is There a Cure for Shingles?
Because shingles is caused by a virus there is currently no cure. Most viruses (such as the common cold) must be treated by treating their symptoms. There are many natural ways to help relieve the symptoms of shingles, many of which are included in the articles on this website. For more information, read on.