Shingles

Shingles, also known as zoster or herpes zoster, is a viral disease characterized by a painful skin rash with blisters in a localized area. Typically the rash occurs in a single, wide mark either on the left or right side of the body or face. Two to four days before the rash occurs there may be tingling or local pain in the area. Other common symptoms are fever, headache, and tiredness. The rash usually heals within two to four weeks; however, some people develop ongoing nerve pain which can last for months or years, a condition called postherpetic neuralgia (PHN). In those with poor immune function the rash may occur widely. If the rash involves the eye, vision loss may occur. Shingles is caused by the varicella zoster virus (VZV) that also causes chickenpox. In the case of chickenpox, also called varicella, the initial infection with the virus typically occurs during childhood or adolescence. Once the chickenpox has resolved, the virus can remain dormant (inactive) in human nerve cells (dorsal root ganglia or cranial nerves) for years or decades, after which it may reactivate. Shingles results when the dormant varicella virus is reactivated. The virus then travels along nerve bodies to nerve endings in the skin, producing blisters. During an outbreak of shingles, exposure to the varicella virus found in shingles blisters can cause chickenpox in someone who has not yet had chickenpox, although that person will not suffer from shingles, at least on the first infection. How the virus remains dormant in the body or subsequently re-activates is not well understood. The disease has been recognized since ancient times. Risk factors for reactivation of the dormant virus include old age, poor immune function, and having contracted chickenpox before 18 months of age. Diagnosis is typically based on the signs and symptoms presented. Varicella zoster virus is not the same as herpes simplex virus, although they belong to the same family of herpesviruses. Shingles vaccines reduce the risk of shingles by 50% to 90%, depending on the vaccine used.