Pretty much the very same answer as the previous answer. I would like to add that once you have had chicken pox, the anti-bodies are still in your body. Also, in my case, I had chicken pox as a child (2 times); first time very mild while second was very bad. As an adult, I had the onset of shingles.
This "supposedly" comes from the chicken pox virus and lies dormant in an adults body. They use they same treatment for shingles as they do for Herpes, by the way, Valtrex.
Chicken pox is usually considered to be a disease of childhood, but adults can get it too. The reason we see it so rarely in grown ups is that once a person has had an attack of chicken pox as a child, he is through with it.
Chicken pox is a very contagious disease. It is believed that a virus causes the disease. It is usually transmitted directly from person to person and not by contact with clothing or other articles soiled by an infected person. A person who has chicken pox can be considered infectious for about 14 days.
This is why the doctors say that the infected person to be kept isolated from the members of the family who have not had the disease, especially the young children. They are also kept from school and all other public places.
One of the problems in connection with this has to do with symptoms of the disease. Some of the symptoms are a slight rise in temperature, loss of appetite, headache and backache. But sometimes the first sign of chicken pox is a rash or eruption of the skin. Since a person with chicken pox can infect another person before the rash appears, you could see how a whole group of children could become infected before anything was done to prevent it.