Clinical Definition

Zoster virus, or Varicella-zoster virus, is a virus that causes varicella and herpes zoster, which are better known as chicken pox and shingles.

In Our Own Words

Zoster virus, also known Varicella-zoster virus, is a highly infectious virus and the cause of chicken pox and shingles. Once you’ve had chicken pox, the zoster virus remains dormant in your body. (Hence, anyone who has had chicken pox can get shingles.) Vaccines are now available for the prevention of both forms of zoster infection.

In about 10 percent of patients who have had chicken pox, shingles will develop, usually later in life. Many people only experience shingles once, but it can return. Doctors aren’t sure what makes the virus reactivate, but both patients and caregivers who suffer from chronic stress, or who have weakened immune systems, are at greater risk.