July 22 (HealthDay News) -- Antiretroviral drugs appear safe and effective in helping prevent the transmission of HIV from mother to child through breast milk, a new international study has found.

The researchers found that giving daily antiretroviral syrup to breast-feeding infants or putting their HIV-infected mothers on highly active antiretroviral drugs significantly lowered the child's chances of contracting the virus that causes AIDS. The chance of a mother with HIV transmitting the virus through breast-feeding is about one in five.

The results of the Breastfeeding, Antiretrovirals and Nutrition (BAN) study, conducted in more than 2,000 HIV-infected mother-child pairs in Malawi in Africa, are scheduled to be presented in South Africa Wednesday at the 5th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention.

"This is an exciting development," lead investigator Dr. Charles van der Horst, a professor in the University of North Carolina School of Medicine, said in a university news release. "We may be able to spare mothers in the developing world a horrible choice by offering them an effective method for preventing transmission of HIV during breast-feeding."

Breast milk is the source of infection for about half of the 420,000 infants who are infected with HIV annually, the study authors noted. This is a particular problem in some poor countries where HIV-infected mothers risk infecting their babies or having to use more expensive formula that is also subject to contamination from local water supplies.

In the BAN study, HIV-infected mothers and their babies were randomly assigned to one of three groups: infant antiretroviral syrup, maternal medication, or no treatment following birth. After 28 weeks, 7.6 percent of the infants in the group that did not receive any treatment had HIV or died, compared with 4.7 percent of infants whose mothers took antiretroviral medication, and 2.9 percent of the infants taking the antiretroviral syrup, the researchers found.

SOURCE: University of North Carolina School of Medicine, news release, July 22, 2009