AZT Cuts Chance of Baby Inheriting HIV, Study Says
For an expectant mother infected with the AIDS virus, the amount of the virus’ genetic material coursing through her blood is a strong indicator of whether she will pass the disease on to her unborn child, scientists said Tuesday.
“If you have a very high [virus] load, your risk is very, very high,” said UCLA pediatrics professor Dr. Yvonne J. Bryson, principal investigator for a study that appears in today’s issue of the Journal of the American Medical Assn.
The researchers also reported that the anti-AIDS drug AZT, also known as zidovudine, can sharply cut both the amount of the virus’ genetic material in the mother and the chance of transmitting HIV to the baby.
The study advances previous work on viral levels and AZT effectiveness. A report earlier this year indicated that people with high blood levels of HIV, the virus that causes AIDS, developed the disease much more quickly. Other research had shown that AZT can cut the chances of mother-to-child transmission from 1 in 4 to 1 in 12.
In the new study, scientists led by Bryson of the UCLA School of Medicine followed 95 pregnancies of HIV-infected women over five years. Through recently developed techniques, they tracked the level of the viral RNA--ribonucleic acid, the virus’ genetic material--in the women’s blood.
None of the 63 women with less than 20,000 bits of HIV RNA per milliliter of blood transmitted the virus to their infants, while three-fourths of the women who did transmit the virus had more than 50,000 bits of HIV RNA per milliliter, the scientists said.
By comparison, long-term survivors of HIV typically have well under 10,000 pieces of virus RNA per milliliter of blood, Bryson said, while people with full-blown AIDS can have levels 100 times that high.
The UCLA researchers found that among the mothers who took AZT during pregnancy, the median level of HIV RNA dropped 90% from more than 43,000 per milliliter to just over 4,200.
Bryson emphasized, however, that low HIV RNA counts do not guarantee the infant will not get the virus. “People should not feel a false sense of security,” she said. During delivery, a baby could swallow blood, for example, exposing it to large amounts of HIV, Bryson said.
Barbara Weiser, co-director of HIV research at the New York Department of Health’s Wadsworth Center in Albany, described the work as “large, careful and well-done.” A smaller study by Weiser and her colleagues found similar results. “Both groups were able to distinguish women with a high risk versus women with a low risk,” she said. But she also stressed that no pregnant woman with HIV is risk-free. “This underscores the need of treating everyone who is pregnant [and HIV-infected] to lower her viral load,” she said.
The UCLA researchers concurred that all HIV-positive pregnant women should be treated with AZT.
Dr. Sheldon H. Landesman of the State University of New York Health Science Center in Brooklyn, co-author of an accompanying editorial in the medical association’s journal, cautioned that several as-yet-unpublished studies will offer different conclusions. In an interview, he said the current work is “good science,” but added, “the predictive value of the HIV RNA [test] in predicting transmission is less than it appears to be based on this article. There are three or four other pieces of data that clearly contradict this.”
But should the results of the UCLA-led study prove correct, the viral RNA count could refine medical treatment of HIV. “If the viral load remains high on currently recommended therapy, we would recommend adding additional treatment [with other drugs],” Weiser said.
