What is shingles?
Shingles is a painful blistering rash caused by reactivation of Chickenpox virus. Chickenpox (varicella) is the primary infection with the virus, Herpes zoster. During this widespread infection, which usually occurs in childhood, virus is seeded to nerve cells in the spinal cord, usually of nerves that supply sensation to the skin. The virus remains in a resting phase in these nerve cells for years before it is reactivated and grows down the nerves to the skin to produce shingles (zoster). This
can occur in childhood but is much more common in adults, especially the elderly.
Shingles is a reactivation of the herpes zoster virus (varicella-zoster virus, or VZV). This same virus causes the childhood illness chickenpox. The chickenpox virus (varicella) remains in a dormant state in the body in the root of nerves that control sensation. In about 1 out of 5 people, the virus "wakes up," often many years after the chickenpox infection. The virus then travels along a sensory nerve into the skin causing a painful rash known as shingles. Shingles is derived from the Latin and French words for belt or girdle, reflecting distribution of the rash in a broad band. This band is usually only on 1 side of the body and represents a dermatome—the area that a single sensory nerve supplies in the skin. Anyone who has had the chickenpox infection or vaccine can get the herpes zoster virus that causes shingles. Older people and those with cancer, HIV, or organ transplants have a decreased ability to fight off infection and a greater chance of getting shingles. The majority of people with shingles, however, are healthy. No special tests need to be done to see if your immune system is strong.
Shingles patients are infectious (resulting in chickenpox), both from virus in the lesions and in some instances the nose and throat. Shingles is more common and more severe in patients with poor immunity. Blisters can occur in more than one area and the virus may affect internal organs, including the gastrointestinal tract, the lungs and the brain. Chickenpox or shingles in the early months of pregnancy can harm the fetus, but luckily this is rare. The fetus may be infected by chickenpox in later pregnancy, and then devlop shingles as an infant. It is not clear why shingles affects a particular nerve fibre. It may be set off by pressure on the nerve roots, by radiotherapy at the level of the affected nerve root, by spinal surgery, by an infection such as sinusitis or by an injury (not necessarily to the spine). Occasional clusters of shingles cases are reported. It is suggested that contact with someone who has chickenpox or shingles may cause one's own virus to reactivate.