Aids Alert International-Can a $4 drug stop vertical HIV transmission?
Barriers are numerous and large, experts say
International HIV/AIDS organizations gave a standing ovation to the recent good news that giving pregnant women and their newborns a $4 dose of nevirapine reduces the transmission of HIV far better than a short course of the much more costly drug AZT.
The good news about nevirapine arrives at a time when about 1,800 infants are born each day with an HIV infection. Even more alarming are the predictions that 45% of pregnant women in parts of South Africa will be infected with HIV by the end of the year.
However, despite the fact that nevirapine treatment is almost 70 times cheaper than a short course of AZT given to the mother during her last month of pregnancy, it will not be the panacea the developing world needs.
The $4 nevirapine treatment may be cheap, but for some nations, it's not cheap enough, and there are still other problems, says Jacob Gayle, PhD, technical advisor/liaison for UNAIDS for the World Bank in Washington, DC.
"In order to make this intervention successful, pregnant women must know their HIV status, and the vast majority of pregnant women in the developing world do not know their HIV status, because voluntary, safe, and ethical testing and counseling options are not made available to them," Gayle explains.
"Clearly, it's not the perfect answer, but it's a great discovery that needs to be followed further to see what its longer term impact might be," he adds.
While it's theoretically possible to stop all perinatal HIV transmission, these barriers make even modest progress in reducing the transmission seem like a lofty goal.
"Money is only part of the issue," says Stefan Wiktor, MPH, MD, medical epidemiologist with the Centers for Disease Control and Prevention (CDC) in Atlanta.
"There seem to be very significant societal barriers to these treatments being widely implemented," Wiktor says.
Many African women are afraid of being identified as having been tested for HIV, and those who are tested may not come back for their results.
"Even where treatment is free and testing is available, many women don't end up getting it by their own choice," Wiktor notes. "And no matter how cheap or easy treatment is, if you can't identify HIV-positive women and you can't get them to agree to take these drugs, then you're no further along."
Another major barrier is the lack of available testing sites outside of research settings, Wiktor says. "There are few places where a woman could get tested for HIV, and it's very expensive and difficult to set up because you need to train people and have extra personnel to counsel women."
Despite the obstacles, the nevirapine study offers hope because it shows that developing nations could make strides in cutting perinatal transmission even if they are not able to put women on a full course of AZT therapy during their pregnancy.
"It's preferred that women are identified early in pregnancy and are started on the regimen as early as they can be after the first trimester," says Lynne Mofenson, MD, associate branch chief for clinical research of the Pediatric Adolescent and Maternal AIDS Branch, National Institute of Child Health and Human Development at the National Institutes of Health in Rockville, MD.
But because that's rarely possible in developing countries, the nevirapine treatment offers a practical alternative. "A single dose to the mother when she comes to the hospital in labor, and a single dose to the baby at three days of age, and that's comparable to an extremely short course of AZT," says Mofenson, who was a co-author of a Uganda study that compared a short course of nevirapine to zidovudine.
"For women coming in late, that seems like a reasonable alternative to what we recommended before," she adds.
Study supports short course with nevirapine
The Uganda study found that nevirapine lowered the risk of HIV-1 transmission during an infant's first four months of life by nearly 50% in a population in which 98.8% of the babies were breast-fed.1
Vertical transmission of HIV through breast-feeding is an even thornier issue for developing nations. Even when women with HIV are given nevirapine or AZT to prevent perinatal transmission, they still may transmit the virus through their breast milk.
And while it's easy for women in developed countries to switch to a formula, women in the developing world may place their babies at a greater risk of death from bacterial and viral diseases if they use a formula that's mixed with contaminated drinking water.
"When you walk through what would be necessary to ensure safe alternatives to breast milk 24 hours a day, it's mind-boggling to realize how simple it would be in some countries and cultures to do so, and how absolutely impossible it might be in many others," Gayle says. (See AIDS Alert International, February 1999, p. 1.)
Reference
1. Guay LA, Musoke P, Fleming T, et al. Intrapartum and neonatal single-dose nevirapine compared with zidovudine for prevention of mother-to-child transmission of HIV-1 in Kampala, Uganda: HIVNET 012 randomised trial. Lancet 1999; 354:795.
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