Test can help predict if baby will get HIV from mother
UCLA doctors find link between virus load, transmittance
By Tiffany McElroy
Daily Bruin Contributor
Following a four year study, UCLA doctors recently developed a
test which will help predict whether pregnant women infected with
HIV will transmit the virus to their unborn children.
The study found that the amount of the virus passing through a
mother’s blood is a powerful indicator of whether it will be
transmitted to her infant.
"If you have a very high virus load, your risk is very, very
high," said Yvonne Bryson, a UCLA pediatrics professor and the
study’s principal investigator.
The researchers found that as the mother’s virus load increased,
her risk of transmittance increased. They also found that
administration of zidovudine (AZT), can decrease the amount of
virus material in the mother and decrease the chance of
transmission to the baby.
"We advise all HIV infected pregnant women about taking AZT
during pregnancy regardless of their virus load," said Ruth
Dickover, co-investigator in the study and a research specialist
with UCLA’s pediatrics department.
"We wanted to determine if levels of HIV-1 in the mother’s blood
are associated with a high or low risk of perinatal transmission
and to determine the effect of AZT treatment on the reduction of
virus load in pregnant women," said Bryson.
"The results of our study suggest that … HIV-1 RNA levels are
one of the better predictors of transmission risk currently
available," she added.
The study followed 92 mostly asymptomatic HIV-positive women
through 95 pregnancies that produced 97 infants. During the study,
none of the women with less than 20,000 units of HIV-1 RNA
transmitted the virus to their infants, while the women who had
more than 50,000 units of HIV-1 RNA in their plasma at delivery
were more likely to transmit the virus to their infants,
researchers said.
Despite the success of the study, researchers said that low
HIV-1 RNA counts do not entirely prevent the transmission of the
virus because the infant can be infected during the actual
delivery.
There are several factors other than viral load involved in
determining the risk of transmission from mother to baby, including
the strength of the mother’s immune response and what happens close
to or during delivery.
"Delivery factors such as the duration of ruptured membranes,
the mode of delivery and the use of mechanical helpers such as
forceps, cannot be accurately predicted ahead of time," Dickover
said. "Babies may be exposed to mother’s blood or cervical vaginal
secretions during delivery."
"In addition, mothers with an initial low virus load during
early pregnancy have no guarantee of a lack of transmission because
virus levels may increase during pregnancy or other unpredictable
factors may allow transmission such as infections of the placenta
or delivery factors," Bryson said.
Not a new subject of research, the transmission of HIV from
mother to infant was analyzed by Barbara Weiser, co-director of HIV
research at the New York Department of Health’s Wadsworth Center in
Albany.
"The UCLA study is an excellent study that has been careful and
well done," Weiser said. "Although we can distinguish high risk
from low risk, we say ‘low risk,’ not ‘no risk.’ No pregnant woman
with HIV is risk free."
Bryson and Dickover said the RNA count study could enhance
medical treatment of the HIV virus if the long term results of the
study prove to be correct.
"This information can help to provide preventive strategies to
get the risk of transmission at an absolute minimum," Dickover
explained.Comments to webmaster@db.asucla.ucla.edu