Varicella-zoster virus (VZV) is a member of the Herpesviridae family of viruses, which are large DNA viruses. VZV belongs to the Alphaherpesvirinae subfamily and is also called human herpesvirus type 3 (HHV-3). VZV is the cause of varicella, also known as chicken pox, a common childhood illness that causes an itchy rash and vesicles (e.g., blisters or pox) all over the body. The first symptoms of chickenpox can include:
- Fever
- Headache
- Sore throat
- Fatigue
- Loss of appetit
Skin lesions follow in one to two days.
Prior to the development of the varicella vaccine, chicken pox occurred in over 90 percent of children. Chicken pox can be severe in pregnant women, adults and people who have immune deficiency syndromes. Following chicken pox, VZV remains in a latent, or inactive, state in nervous tissue (dorsal root ganglia), but it can reactivate following periods of stress or many years following chicken pox as immunity wanes. Reactivation usually occurs in nerves that supply a single region of the body or dermatome. This reactivated VZV infection is called zoster or shingles and presents with severe pain associated with vesicles that occur on the face or trunk. The reactivation of VZV can also cause severe infections of the nervous system including meningitis and encephalitis.
