July 25, 1997

Reducing HIV transmission to newborns goal of new clinic

Reducing HIV transmission to newborns goal of new clinic

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Dr. Greg Wilson (right), here working with student William McRae, is seeking to lower the incidence of HIV transmission to newborns. Photo by Donna Marie Jones.

A new Vanderbilt program of the Division of Pediatric Infectious Diseases is seeking to both lower the odds that HIV-positive mothers will pass the virus on to their children and improve clinical outcomes in those who are infected.

Currently 25 percent of children born to HIV infected mothers become infected with the virus

"Our goal is to bring that number down to 8 percent or lower," said Dr. Greg Wilson, assistant professor of Pediatrics.

To help reach that goal, preparations are under way to open the Pediatric AIDS Clinical Trials Unit (PACTU), which will allow VUMC to begin trials of both new medications and more potent versions of old ones.

"This will also allow us to look at the use of immune-based therapies, such as vaccines, to affect mother-to-baby transmission," said Wilson.

One of the questions PACTU will attempt to answer is why some children get HIV during delivery and others do not.

"We know that the majority of virus transmissions occurs at the time of delivery, when the child is exposed to maternal birth secretions and blood," said Wilson.

The current theory is that transmission is influenced by the level of the mother's viral load.

"That can't be the only answer because there are mothers who have their diseases under control who transmit HIV to their babies and there are mothers whose disease is out of control whose babies do not get HIV," said Wilson.

PACTU will also allow children and mothers access to clinical trials, which gives them the opportunity to participate in the introduction of new therapies.

The development of drugs for children is an important step in treating pediatric AIDS with as much intensity as researchers are currently direting towards AIDS in adults, said Wilson.

"Though I don't think their care has suffered, there has definitely been a delay in the development of drugs to treat children. Formulations, such as liquid forms of the protease inhibitors, have not become available as fast as we would like to see," said Wilson.

Medications that work in children, like liquid forms and dosage recommendations for the protease inhibitors, must be developed in order to suppress the virus with the success now seen in adults.

"We have been able to suppress the virus in the older children but not in the younger ones. It is my hope that the Pediatric AIDS Clinical Trial Unit will help us do that," said Wilson.

To become a part of the AIDS clinical trials unit a child must first undergo a screening process. The diagnosis can be confusing since all children born of HIV positive women will generally have HIV antibodies present at the time of birth.

"Antibodies received from the mother protect a child from disease while the baby's own immune system is learning to cope. In the case of HIV they also complicate the diagnosis since we can't tell if the HIV antibodies are a response to the HIV virus or the remaining maternal antibodies," said Wilson.

The mother's HIV antibodies disappear within 18 months of birth. If HIV antibodies are still present in the body after 18 months, then doctors know the child has the HIV virus.

Newer techniques, such as PCR, which measures viral load, and viral cultering, are now allowing us to make the diagnosis earlier in many cases.

Once it is determined that a child has the HIV virus the Pediatric HIV/AIDS Clinic will either refer them to a infectious disease specialist in their area or they will be treated here at VUMC.

The treatment of AIDS in children is a difficult time not only for the children, who must face the disease, but also for the parents, who, in many cases, have to tend to the child's needs as well as care for their own health needs.

"Pediatric diseases are different because it is not only the child that is involved, but also the parents," said Wilson.

The goal of the Vanderbilt Pediatric HIV/AIDS Clinic is to provide multidisciplinary care for pediatric HIV and AIDS patients.

The addition of PACTU will allow even more advanced care for children and their mothers.