Varicella

Chickenpox is caused by the varicella virus or herpes zoster. Once infected with chickenpox, a susceptible individual can carry the virus in the para-spinal and other nerve ganglia for life. The virus can re-emerge at multiple times and at any point in later life along the sensory nerves of those ganglia erupting in patches of painful, clear vesicles, a condition called shingles. Vaccination usually results in immunity to chickenpox and precludes the subsequent occurrences of shingles. The virus can cause primary chickenpox in utero if susceptible mothers contract it.