In fact it's estimated that about 4 million Americans, mostly children, contract chickenpox each year. Yet adults also can become infected. Chickenpox is caused by the varicella-zoster virus, a type of herpes virus. This virus is easily spread from person to person through the air and physical contact. Outbreaks of chickenpox are common in late winter and early spring periods of moderate temperatures when viruses thrive.
Most people think of chickenpox as a mild disease and, for most, it is.
In otherwise healthy children, chickenpox lasts 2 weeks or less and rarely causes complications. But for adults who've never been in contact with the virus and get sick later in life, chickenpox can be serious. Complications from chickenpox can result in hospitalization and can even be life-threatening. Until 1995 when a vaccine to prevent chickenpox became available nearly everyone developed chickenpox in childhood. Today, children are routinely immunized against chickenpox.