Cause of Chickenpox & Shingles

Approximately 90 percent of chickenpox cases occur in children under 10 years of age. The infection is usually transmitted by airborne droplets containing the virus. Less often, the virus is spread by direct contact with the blisters.

After exposure, the typical incubation period is 2 weeks. One is contagious a couple of days before the rash appears. Rarely, chickenpox is transmitted through the blood of an infected mother to a fetus.

Shingles cannot be acquired from another person. Shingles is caused by reactivation of the dormant virus.

While shingles can occur at any age, more than two-thirds of cases occur in people over 50 years of age. Shingles is 20 to 100 times more common in people with a compromised immune system, such as patients with chronic diseases and the elderly, as well as those whose immune systems are suppressed by medication or chemotherapy. A person who has never had chickenpox could develop the infection by coming into contact with shingles blisters.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 02 Sep 2000

Last Modified: 04 Sep 2015