HIV infects an estimated 430,000 infants and children worldwide each year. Although many of those cases are contracted from an HIV-positive mother during pregnancy or birth, some 40 percent of infected children get the disease through breast-feeding. But because of health risks associated with formula feeding—especially in resource-poor regions—the World Health Organization still recommends breast-feeding for mothers with HIV/AIDS in the developing world. Left untreated, however, about half of HIV-infected infants die before the age of two.

Giving HIV-positive mothers antiretroviral therapies has been shown to reduce transmission rates during pregnancy and birth as well as during breast-feeding, but the postpartum infection rates remained variable. And in the larger population, by six months of age, about a quarter of babies whose mothers had HIV had also contracted the virus. A new study conducted in Botswana, published online June 16 in The New England Journal of Medicine, reports a breast-feeding transmission rate of just 1.1 percent with the use of prophylactic antiretrovirals.

"This is the lowest rate of mother-to-child transmission in a study from Africa, or among breast-feeding infants," Roger Shapiro, an associate professor of medicine at Harvard Medical School and lead author of the new study, said in a prepared statement.

The trial compared three highly active antiretroviral therapy (HAART) treatments. Five hundred and sixty pregnant women who would not have met qualifications for antiretroviral treatment normally (who had CD4+ counts of more than 200, a measure of immune cells that indicates a low progression of HIV) were randomized to either a nucleoside reverse-transcriptase inhibitor or protease-inhibitor group. One hundred and seventy women whose infections were worse and met qualifications for treatment on their own (with CD4+ counts of less than 200 cells per cubic millimeter) were placed in the control group and given standard-of-care antiretroviral treatment. The two experimental treatments were given to the mothers from late pregnancy through six months after birth, and the breastfed infants received five doses of drugs as well.

Of the 709 live-born infants in the study, eight had HIV by the age of six months. The protease-inhibitor group had a slightly lower rate of overall transmission (0.4 percent versus 2.1 percent for the nucleoside reverse-transcriptase inhibitor group), but the number of subjects was not sufficient to establish this difference as statistically significant.

The findings are good news for many HIV-infected mothers, who "were faced with a choice between breast-feeding and a high risk of infecting their children with HIV, or using formula and risking high infant morbidity and mortality from other diseases associated with not breast-feeding," Max Essex, a professor of health sciences and chair of the Harvard School of Public Health AIDS Initiative and coauthor of the study, said in a prepared statement. "This study provides a more satisfactory solution."

The researchers cautioned, however, that infants whose mothers were taking the protease-inhibitor therapy had a 23 percent chance of being born prematurely, which can increase the risk of other health problems down the road.

In a separate study, published in the same issue of The New England Journal of Medicine, another group of researchers found that just providing infants with prophylactic antiretrovirals during infancy can also reduce the chances they will contract HIV through breast-feeding.

The researchers randomly assigned 2,369 breast-feeding mothers (and their infants) in Malawi to one of three groups: one in which the mother alone received antiretroviral therapy for the first seven months after the birth of the baby, another in which the infants were given nevirapine (a nucleoside reverse-transcriptase inhibitor) for seven months, and a third, control group, in which medication was delivered to mothers and babies only at birth and for the first week postpartum.

"Our study found that both [experimental] methods are effective in preventing HIV transmission," Charles Chasela, a researcher with the University of North Carolina (UNC) Project-Malawi, and lead author of the study, said in a prepared statement. After seven months, the infant-treatment method had a 74 percent success rate in preventing transmission through breast-feeding (and the maternal-treatment method was 53 percent effective). "Given the choice between the two," Chasela noted, "I'd say that the baby regimen is the more successful method."

The infant-based prophylaxis might also be more practical. "The antiretroviral regimen for treating mothers is much more expensive and requires access to medical facilities that aren't widely available in developing countries," Charles van der Horst, a professor of infectious diseases at the UNC School of Medicine and coauthor on the study, said in a prepared statement. "The baby regimen, in comparison, is incredibly cheap and much easier to implement."

In an editorial accompanying both studies in The New England Journal, Lynne Mofenson, chief of the Pediatric, Adolescent and Maternal AIDS branch of the National Institute of Child Health and Human Development at the National Institutes of Health, noted that together the studies provide hope for quelling the spread of HIV to coming generations of children born to mothers with the disease. "It should be possible to eliminate new perinatal HIV-1 infections globally with the use of antiretroviral therapy," Mofenson noted. "We now have the tools to make a considerable difference in controlling the pediatric HIV-1 epidemic. A generation of children awaits our actions."

Image of woman and child in Botswana courtesy of iStockphoto/poco_bw