One of the mysteries of HIV is why it doesn't surface in all the children born to infected mothers. Even at its worst, notes Warren A. Andiman, M.D., professor of pediatrics and epidemiology, it only struck about 20 percent of children of HIV-positive mothers. Prevention programs and use of AZT have reduced the figure in New Haven from between 16 and 18 percent to about 2 percent.

A related riddle is why some strains of the virus found in the mother emerge in the child and others don't. “Is there a pattern to the kind of strain that a baby gets from among the strains that the mother has? Is there a selective process that goes on which determines whether a certain kind of virus is being transmitted from the mother to the baby?” Dr. Andiman asks. “It will be useful to learn something about how rapidly the virus changes. It would give us a sense of when an intervention might still be worthwhile. You would want to provide therapy before the virus becomes very virulent.”

Dr. Andiman directs the pediatric AIDS program at Yale-New Haven Hospital and is studying the virus to find ways to prevent and treat infection. His research led him to participate in an international study evaluating Caesarean section as a means of protecting newborns from infection. Many infections occur during passage through the birth canal.

A current laboratory-based study explores how biological characteristics of the virus affect clinical outcomes. Are there specific behaviors of the virus that determine whether an infected child suffers a rapid progression of disease or becomes a long-term survivor? If so, can less virulent strains of the virus be isolated and used in vaccines? Or can different viruses with useful traits be combined into a single vaccine?

The 75 HIV-infected children in the AIDS program are part of a long-term observational study to determine their survival and to find out what opportunistic diseases emerge. “These kids are followed primarily to provide clinical care. At the same time we have very careful observation of the history of the disease. The primary reason for seeing them is to take care of them, not because we're doing the study,” he says.

Children with AIDS suffer learning disabilities, problems with motor functions and cognitive skills, cognitive retardation, fungal infections of the esophagus and various viral and bacterial infections. The problem becomes one of managing the disease, far more difficult in children than adults. “The medicines taste nasty. The pills are very big. There are side effects,” says Dr. Andiman. “We have a lot of kids in their early teenage years who were infected when they were infants, with many medical problems. Most of them are not robust children.” But he adds, “It has truly turned into a chronic disease. If children don't succumb to the disease in the first three years of life, they really become long-term survivors.”