February 6, 2001
In the lead-off talk of a symposium on maternal fetal transmission, the CDC's Mary Glen Fowler gave a comprehensive overview of the progress and challenges in preventing the transmission of HIV from mother to child. She reviewed the striking progress in the U.S. and Europe that began around 1994 with the report of PACTG 076. The transmission rate has fallen progressively as we have moved from the era of AZT therapy, to dual nucleosides, to triple combination HAART. Reviewing several data sources, Dr. Fowler cited a transmission rate of about 1% for women on HAART. A meta analysis of the role of maternal viral load that will be presented later in this conference showed that when the viral load is less than 1,000 copies, the transmission rate will be less than 1%. In developed countries the Caesarian section rate is rising dramatically, but it is not clear whether that represents appropriate use among women with poorly controlled viral loads or who opt for C-section when the benefits are unclear, or whether this is over-use based on the benefits for women on less aggressive therapy.
In the developed world, the number of pediatric AIDS cases has fallen 80% but challenges remain. Those who present late or with no prenatal care, those who are never offered testing, and hose who never take their HIV meds represent challenges to our health care delivery system.
In contrast, there are unique challenges faced in the developing world, where most of the cases of mother-to-child transmission occur. This is despite the progress in demonstrating simple regimens that can prevent 30% to 55% of infections. There is a rapid increase of infection at a very young age in adolescent women, very high seroprevalence, inadequate infrastructure for voluntary testing and counseling, few safe alternatives to breast feeding, and limited resources with many competing health needs. Dr. Fowler reviewed issues around breast-feeding and transmission, which confers a 10% to 14% risk of infection. First, she emphasized that long-term follow-up in several trials shows that the benefits of early intervention with nevirapine or AZT are maintained after a year despite additional infections. This is in contrast to the results from PETRA, which were given a great deal of public attention last summer. The risk associated with breast feeding continues throughout breast feeding and is associated with maternal viral load, duration of breast feeding, and mastitis, abscess or bleeding nipples. When a woman seroconverts during breast feeding, there is a six-fold increase in the risk of infection. Research on breast-feeding and transmission must be a priority, according to Fowler.
The challenges that remain are to improve access to voluntary counseling and testing, including dealing with fear, stigma and lack of treatment, improving primary prevention, decreasing heterosexual transmission, and learning how to deliver preventive antiretroviral therapy. This call for operational research echoed that of Kevin DeCock from the moving opening plenary session. The time has come to quickly learn how best to apply the scientific advances to the majority of people affected by the pandemic.
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