Perinatal Transmission. Scientific Areas of Emphasis
In the United States, widespread HIV testing of pregnant women and the use of AZT alone and in combination with other antiretroviral drugs in pregnant woman and their newborns has reduced the incidence of perinatal transmission of HIV by nearly 70%. Unfortunately, these dramatic results have had not altered the grim situation in developing countries, where most of the infections occur.
Nearly 90% of all HIV-infected babies are born in Africa and according to UNAIDS there were an estimated 1.4 million children worldwide under age 15 living with HIV/AIDS at the end of 2000. Almost all HIV-infected children acquire the virus from their mothers before or during birth or through breast-feeding.
Specific areas of research emphasis include the following:
- Interventions to Further Reduce Transmission
- Factors Associated with Transmission
- Implementation/Operational Research
Interventions to Further Reduce Transmission
While greatly reduced, perinatal transmisison of HIV has not been elimianted in the United States. High adolescent pregnancy rates among at risk populations, failure to identify HIV infection during pregnancy, and inadequate prenatal care for many HIV-infected women remain obstacles in the prevention of perinatal transmission.
In the United States and other developed countries research will focus on combinations of antiretroviral agents, the use of vaccines in newborns, the widespread feasibility of HIV testing of women in labor whose HIV status is unknown and post-exposure infant prophylaxis of women first identified during labor.
In developing countries, research will focus on the feasibility and acceptability of prenatal HIV testing, as well as rapid HIV testing during labor. In addition, the evaluation of Nevirapine and other interventions will be needed in breast-feeding populations.
Other non-antiretroviral interventions will also be evaluated, including vaginal microbicides, passive and/or active immunization, antenal/intrapartum antibiotic prophylaxis of chorioamnionitis, and nutritional interventions. Researchers will also continue to evaluate use of elective Ceasarean-sections, which have also been shown to greatly reduce mother to infant transmission of HIV in women taking AZT monotherapy or nothing at all.
Factors Associated with HIV Transmission
In the United States, research will focus on the factors associated with perinatal transmission of HIV in women who are receiving antiretroviral therapy to determine:
- the mechanism and timing of in utero and intrapartum transmisison;
- the role of maternal virologic, cellular and humoral immunologic, genetic and other factors (e.g., chorioamnionitis);
- and the impact of drug resistance.
In developing countries, it will be important to discern whether there are risk factors for transmission specifically related to the conditions in the developing world, such as other infectious diseases or viral genetic subtype.
Breastfeeding if you have HIV
Although breastfeeding is normally the preferred way to nourish infants, HIV can be transmitted by breast milk. In order to develop safe and effective interventions to reduce perinatal transmisison via breast milk, an improved understanding of the pathogenesis of postnatal HIV transmisison is needed.
Studies will examine the role of maternal and infant immune response, virologic factors and the influence of other maternal- and infant-specific factors in breast milk transmission. In addition, clinical trials will evaluate different strategies, such as antiretroviral interventions, vaccines, early weaning and/or breast milk substitutes, to reduce transmission via breast milk.
Safety precautions for mother with HIV
The long-term effects of in utero antiretroviral drug exposure on the fetus and infant are unknown. Animal model and laboratory related evaluations will examine the impact of these drugs crossing the placenta, the possible incorporation of drug into host DNA, potential mutagenic, chromosomal and/or mitochondrial abnormalities as well as the durability of any such changes after antiretroviral prophylaxis has stopped.
The long-term effects of exposure to antiretroviral drugs will continue to be examined and the development of innovative follow-up strategies of infants involved in future studies will also be explored.
Although effective regimens have been identified to reduce mother to infant transmission, these interventions are not universally used.
Research is needed to identify and determine how to overcome these obstacles. In the United States and other developed countries, the barriers and acceptability of counseling and testing, prenatal screening, and rapid HIV testing during labor will continue to be examine.
In developing countries research will focus on issues related to infrastructure, feasibility, and acceptability of various interventions.