FAMILY MEDICINE® COLUMN
By John C. Wolf, D.O.
Associate Professor of Family Medicine®
Ohio University College of Osteopathic Medicine

KID CAN CATCH CHICKEN POX FROM ADULT WITH SHINGLES

[Editor's Note: In this column Dr. Wolf deals with two related questions from two readers.]

Question: My mother, at age 55, came down with chicken pox that she caught from one of my brother's children. She took care of me and my brother and sister when we had chicken pox as children. What I don't understand is how she could have taken care of us when we had chicken pox and not have gotten the infection herself?

Answer: Chicken pox is a very common childhood illness that results from infection by the varicella zoster virus. It causes the fever, cough and itchy, red "spots" characteristic of the illness. The infection is spread by very fine droplets of virus-infested secretions that the infected person sprays about when he or she coughs and sneezes.

Chicken pox is very contagious. Eighty-five to 95 percent of exposed individuals develop the infection. It usually takes about two weeks from the time of exposure until the fever and sores become apparent. Your mother didn't have the illness when she was a child, since one gets chicken pox only once, and she also didn't get it when her children had it. There are several possible medical reasons for this, but it may also just be a matter of luck. The important issue is that she has the infection now.

Chicken pox is usually a fairly mild illness. In children, the most common complications are pneumonia or encephalitis, which cause death in less than one person out of each 100,000 infected. Adults, like your mother, don't fare quite as well, but still the vast majority of them recover completely. Specifically, varicella causes pneumonia in about 15 percent of adults, and this and other complications result in slightly more deaths 17 per 100,000.

Fortunately, most individuals have this illness as children when the chances of complications are low. There is a vaccine against chicken pox, but it isn't used in this country because of concerns that it may not provide lifelong immunity. Failure of immunity years after the shot could cause many adults to develop chicken pox at a time when the risks of complications are higher.

Question: A friend of mine claimed that she had gotten shingles by being around a child with chicken pox. She said that her doctor told her exposure to a kid with active chicken pox can trigger shingles in an adult who had shingles as a child. This sounds rather far-fetched to me. Is there any truth to it?

Answer: Chicken pox and shingles are caused by the same varicella zoster virus. The first exposure to it causes chicken pox. Unfortunately, the human immune system doesn't kill this invader, it only controls it. Getting the infection under control requires a bit of time that week or two of the chicken pox illness. Once the body has made antibodies to control the varicella infection, the person is also "immune" to developing another case of chicken pox. Illness, advancing age, or medications that compromise the effectiveness of the immune system can allow the dormant virus to start reproducing and causing illness again. The virus comes out of its hiding places along the roots of spinal nerves and causes a painful rash of small blisters along the path of the involved nerve or nerves. This illness, even though we now know it is actually a continuation of chicken pox, is called shingles, as it has been for generations.

So, exposure to the virus as chicken pox doesn't cause shingles immediately it takes years, and frequently 60, 70 or more of them. Re-exposure to chicken pox once you have had the illness only heightens your body's immune response. This would tend to prevent, not cause, an attack of shingles. The reverse, however, is a concern. The fluid in a blister of shingles contains the varicella zoster virus that can spread chicken pox to previously unexposed children and adults.

Family Medicine® is a weekly column. To submit questions, write to John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, Grosvenor Hall, Athens, Ohio 45701.