Human Varicella-Zoster immunoglobulin

Shingles and chicken pox are both caused by the same virus of the herpes family known as Varicella-Zoster Virus (VZV). The word herpes is derived from the Greek word 'herepein', which means 'to creep,' a reference to the characteristic pattern of skin eruptions. VZV is still referred to by separate terms:

Varicella: the primary infection that causes chicken pox.

Herpes Zoster: the reactivation of the virus that causes shingles.

Chicken pox is a common childhood disease with symptoms of slight fever, physical discomfort, uneasiness and skin rashes that blister into itching sores which eventually scab. In adults, a chicken pox infection is more severe than in children; many infected adults can develop pneumonia.

Shingles is a reactivated disease that appears in older adults who were previously infected with the virus.  The virus lies dormant in the spinal cord for years.  When reactivated it affects the nervous system and causes inflammation of the nerve fibres of the skin. These are bundles of nerves that transmit sensory information from the skin to the brain. Here, the virus has properties that allow it to hide from the immune system for years, often for a lifetime. This inactivity is called latency. Shingles is more common after the age of 50 and the risk increases with advancing age. Shingles causes numbness, itching and often severe pain followed by clusters of blister-like lesions in a strip-like pattern on a section of one side of the body. The pain can persist for weeks, months or years after the rash and infection heals and is then known as post-herpetic neuralgia.

It is not clear why the virus reactivates in some people and not in others. In many cases, the immune system has become impaired or suppressed by aging, or exceptionally from immunodeficient diseases (e.g. AIDS) or from certain cancers or drugs that suppress the immune system. 

Varicella-Zoster immunoglobulin (VZIg) is recommended for individuals who are at increased risk of severe varicella and who have no antibodies to Varicella-Zoster virus and who have significant exposure to chickenpox or herpes zoster. Those at increased risk include pregnant women with no previous history of this virus infections who become exposed to anyone who has come into contact with the virus; also newborn babies of women who develop chicken pox in the period 7 days before to 7 days after delivery.