In light of the fact that the number of HIV-infected women
increases every year, it may seem that the number of newborns
contracting the virus should also increase. But HIV in infants has
reached such a low rate in the United States that many experts hope
to see its presence in newborns eradicated.
HIV ““ which in its fully developed form becomes AIDS
““ infected 1,000 to 2,000 infants each year in the early
1990s, reflecting the virus’s approximate 25 percent rate of
transmission from an infected mother to her child, according to the
Center for Disease Control and Prevention. In some countries, this
rate is as high as one in three births. Currently, it is estimated
that the U.S. rate is only 2 percent.
So why has there been such a dramatic drop in perinatal HIV
transmission? Dr. Paul Krogstad of the UCLA AIDS Institute says
“the answer is that we are seeing better obstetrical care,
and improvement of treatment of the virus in mothers, and improved
knowledge of how to treat babies after delivery.”
By engaging in a multi-pronged approach to HIV prevention in an
infant’s perinatal stage ““ five months before a
child’s birth and one month afterward ““ doctors
nationwide are effectively limiting the virus’s passage from
mother to child.
In particular, the application of the drug Zidovudine has been a
crucial component to the success of this approach. Zidovudine slows
the progression of HIV into AIDS.
Krogstad explained that because of what is now known about the
transmission of HIV from a pregnant woman to her child, certain
vital steps are taken during pregnancy to minimize risk of
infection.
When a woman’s pregnancy is confirmed by her doctor, he
most often offers her an HIV test ““ in some states one must
be offered by law, including California.
If the woman is found to be HIV-positive, additional tests are
performed to evaluate the progression of the disease so that
treatment for her can be considered. While there is no cure yet for
HIV, current drugs can slow its progression to AIDS, which is
fatal, and preventing this progression is key to keeping it from
being passed from mother to child.
The expectant mother then receives Zidovudine and other drugs
beginning in her second trimester, and is given the drug
intravenously during pregnancy. A cesarean section birth also
reduces the risk of infection.
Finally, the infant is given Zidovudine for the first six weeks
after its birth and is closely monitored for signs of the
virus.
Krogstad added that while “it’s still not clear
whether or not a woman is going to transmit the virus if you did
nothing,” these are the best means as of yet to lower the
risk that a child will be born with HIV.
Krogstad also noted that “Zidovudine has been used
apparently with great safety over the past 13 years,” but is
now more effective as it is paired with other treatments.
Zidovudine works as a nucleoside reverse transcriptase
inhibitor, meaning it prevents HIV from reproducing itself in
infected antibody cells. Since retroviruses like HIV are reliant on
using the replication tools of their hosts cells for propagation,
preventing them from creating more virus DNA slows their spread. It
does not eliminate the virus.
When an infant is developing, it has its mother’s
antibodies, and will test as infected while still in the womb.
After birth it acquires its own antibodies ““ which are not
infected ““ and it becomes essential to use Zidovudine to
suppress the virus in the mother’s antibodies as they are
being phased out of the child’s body.
UCLA research has been integral in the development of new
approaches to controlling AIDS. UCLA researcher Yvonne Bryson
participated in the initial Zidovudine trials in the 1980s and
1990s, which led to its rapid approval by the Food and Drug
Administration.
In 1991, the UCLA AIDS Institute was founded as a federally
sponsored research facility through the National Institutes of
Health with the goal of uniting medical scientists from a variety
of specializations to focus on containing the AIDS epidemic.