Herpes zoster, also known as herpes zoster, is caused by infection with the varicella-zoster virus. When first infected with the virus, it may appear clinically as chickenpox or as an insidious infection. The virus then enters the sensory nerve endings of the skin and moves centrally along the nerve fibers of the ganglion, where it can be latent in the neurons of the ganglion in the posterior roots of the spinal cord. In response to decreased resistance, exertion, or other stimuli, the virus can reactivate, grow and multiply, causing inflammation and necrosis of the affected ganglion, resulting in neuralgia. At the same time these reactivated viruses move along the peripheral nerve fibers to the skin, producing segmental blistering rashes on the skin, which is how herpes zoster develops.