Two studies published online by the New England Journal of Medicine offer important insight into current practices aimed at preventing mother-to-child transmission (MTCT) of HIV in the developing world. One study concludes that abrupt cessation of breast feeding by HIV-infected women in resource-poor nations is not only unwarranted for children who are exposed to HIV but uninfected, but it is also potentially harmful for infants who are known to be infected with HIV. The second study indicates that extending a standard antiretroviral regimen used by breast-fed infants born to mothers with HIV can further reduce the risk of MTCT.
The first study, conducted by Louise Kuhn, PhD, of the Mailman School of Public Health at Columbia University, and her colleagues compared the infection and death rates among two groups of infants born to 958 HIV-positive women in Zambia: those who were abruptly weaned at 4 months old and those whose mothers were encouraged to breast-feed for as long as they desired (an average of 16 months).
While breast feeding is a known risk factor for HIV transmission, it is also protective against common and potentially fatal diseases, including diarrhea and pneumonia, in resource-poor areas of the world. Research also shows that infants who are exclusively breast-fed after birth are less likely to be infected with HIV than those who are mixed-fed—i.e., fed both breast milk and formula.
Current health practices in many resource-poor nations dictate exclusive breast feeding for four to six months, followed by a transition to formula. What hasn’t been clear is whether continued breast feeding, beyond the first few months of infancy, is associated with an increased risk of HIV transmission or death compared with abrupt switches to formula feeding.
The study found no differences in HIV-free survival between the two groups of infants, indicating that prolonged breast feeding is not associated with an increased MTCT risk. Approximately 68 percent of the abruptly weaned infants, compared to 64 percent of those who continued being breast-fed, were alive two years later without HIV infection. Similarly, among infants who were still being breast-fed and were not infected with HIV at 4 months old, a similar proportion of infants were alive, without HIV infection, after two years.
Prolonged breast feeding actually conferred a benefit for infants who were infected with HIV by 4 months old, the researchers reported. Approximately 73 percent of the HIV-infected infants weaned at 4 months old were dead by 24 months, compared with 55 percent of those who continued to be fed breast milk.
“[This] research,” says Cathy Wilfert, MD, scientific director of the prevention of mother-to-child transmission at the Elizabeth Glaser Pediatric AIDS Foundation, “will give millions of young children who begin life in precarious circumstances a chance to live healthy and long lives.”
The second study, conducted by Newton Kumwenda, PhD, from the Bloomberg School of Public Health at Johns Hopkins University, and his colleagues followed 3,016 Malawian infants born to HIV-positive mothers for two years. All infants received single-dose Viramune (nevirapine) immediately after birth, followed by a one-week dose of Retrovir (zidovudine) to prevent HIV infection. One group received an additional 14 weeks of Viramune, while another received an additional 14 weeks of Viramune combined with Retrovir.
Approximately 90 percent of the women were still breast-feeding their infants, six months after delivery.
Throughout, the breast-fed infants who received the extended preventive regimens had consistently lower rates of HIV infection compared with children who received the standard one-week regimen. At 9 months old, approximately 5 percent of the infants received extended Viramune, and more than 6 percent of infants receiving extended Viramune and Retrovir contracted HIV—compared with more than 10 percent of infants receiving single-dose Viramune and one week of Retrovir.
“We know that breast feeding in the first six months of life is extremely important for the child's health and survival, especially in resource poor countries. However, women with HIV face a difficult choice because they are also putting the child at risk for HIV," said Taha E. Taha, MD, PhD, an author of the Malawi study and professor in the Bloomberg School’s Department of Epidemiology. “Our findings clearly show that extended drug regimens can significantly reduce the risk of HIV transmission from breast feeding.”
