Much of NICHD's HIV and AIDS research seeks to prevent HIV transmission from mother to child, and to understand the disease in adolescents. New NICHD studies uncovered affordable ways to help prevent transmission in poor countries unable to provide expensive anti-HIV treatments. Other research findings shed new light on how the course of infection may differ in HIV-infected teens.

Affordable Options for Poor Countries. By the end of 2002, an estimated 42 million people worldwide were infected with HIV.[1] The global epidemic was disproportionately concentrated in sub-Saharan African and other countries that could least afford programs to prevent and treat HIV infection. Of the estimated 800,000 new cases of HIV resulting from mother-to-child (vertical) transmission, 90 percent occurred in sub-Saharan Africa.[2] The risk of vertical transmission can be reduced if an HIV-infected woman is treated with zidovudine (ZDV) during pregnancy and labor, in addition to treating her newborn. A shortened treatment with ZDV, at the time of birth, can also reduce transmission of the virus. But infected mothers can pass HIV on to their infants during breastfeeding. In the developed world, mothers with HIV are advised not to breastfeed, but to give their infants formula, instead. In developing countries, however, formula feeding may pose a danger of its own. In areas lacking water purification systems, disease organisms in the water used to prepare formula may pose an even greater danger than does HIV. By 1999, researchers conducting a study in Uganda reported that giving single doses of the inexpensive drug nevirapine to HIV-infected women as they were giving birth and to their newborns reduced the chances of vertical HIV transmission by 47 percent when infants were tested for infection at three months of age. However, there still remained the concern about longer-term protection because nearly all of the women in the study breastfed their infants for about 9 months. Researchers continued to follow the infants and recently reported that nevirapine-treated infants were still much less likely to be HIV-infected when the infants were 18 months old.

Pregnancy and Progression of HIV Disease in Women. Although ZDV sharply reduces a pregnant woman's chances of passing HIV on to her child, many are concerned that this benefit would come at the expense of the mother's own health. Specifically, could women in the early stages of HIV infection, who would not take anti-HIV drugs if they were not pregnant, speed the course of their own disease? Could such temporary exposure to ZDV allow the virus to develop resistance to the drug? NICHD-supported scientists recently found that when pregnant women in the earliest stages of HIV infection took ZDV temporarily, they did not experience accelerated HIV disease or excessive ZDV resistance for as long as four years after giving birth. Another study of women who took ZDV during a more advanced stage of HIV disease found a significant but very small increase in levels of the virus 18 months after the women gave birth. Because this small increase occurred both in women who stopped ZDV after delivery and those who continued it, scientists think that the slight elevation in HIV virus levels could stem, at least in part, from such pregnancy-related factors as changes in hormone levels or maternal blood volume following delivery. The findings from the two studies indicate that temporary use of ZDV during pregnancy and delivery neither accelerates HIV disease nor negatively affects a woman's response to later drug therapy. In another study, researchers found that a second pregnancy in an HIV-infected woman who has already had a child does not significantly affect the course of her disease. Together, these studies should help HIV-infected women and their physicians make more informed choices to protect the health of the mother as well as that of her child.

Clue to Adolescent Immune System's Response to HIV Infection. Half of all new HIV infections occur in young people under 25 years of age.[3] Since the time between HIV infection and AIDS diagnosis averages about ten years, scientists believe that many, if not most, adults diagnosed with AIDS in their twenties were infected with the virus as adolescents. However, little is known about the HIV disease process in adolescents and about the best ways to treat the disease in this age group. Because so many developmental changes are occurring, treatments suitable for adults may not apply to adolescents who are infected with HIV. Researchers recently uncovered an important clue to better understand HIV infection in adolescents. Adolescents with HIV appear to have a higher number of the infection-fighting T-cells than do adults with the virus. These cells are a special target for the HIV virus. Researchers discovered that adolescents in the early stage of HIV infection had an unexpectedly disturbed immune response. The disturbance coincided with the virus reproducing itself rapidly. This altered immune response may indicate that the adolescents' immune systems are already affected even before the infection can be detected by standard monitoring. What appeared to be a clinical state of equilibrium between the immune system and the virus, in reality, may be masking a profound change in immune cell function in HIV-infected youth. This finding opens intriguing questions about the processes of HIV infection and immune-system destruction in adolescents and suggests that this age group may need interventions that go beyond the current approaches to treat HIV in adults.