Longer Drug Regimen Found to Help Babies Avoid H.I.V.

BOSTON — Over recent years, giving an antiretroviral drug to a woman infected with the AIDS virus in labor and to her baby at birth has reduced the risk of transmitting the virus to the baby.

Yet many babies born uninfected go on to acquire H.I.V., the AIDS virus, in the lengthy period of breast feeding because of contamination of the mother’s milk.

Now researchers have found for the first time that the incidence of the virus among breast-fed infants can be significantly reduced by extending antiretroviral drugs for much longer periods, up to six months, according to a number of studies reported on Monday at a scientific meeting here.

“Making breast feeding safe is an urgent need,” Dr. Taha Taha, a researcher from Johns Hopkins who led a study in Malawi, said at a news conference.

Breast feeding accounts for up to 48 percent of H.I.V. infections among infants in developing countries, researchers said.

The findings open the way for new prevention strategies in areas where infected mothers cannot avoid breast feeding for a number of reasons. They include lack of access to formula, strong cultural traditions of breast feeding and reluctance to use formula for fear of being stigmatized as being infected, the federal Centers for Disease Control and Prevention said.

The agency paid for three of the five breast-feeding studies reported at the 15th Conference on Retroviruses and Opportunistic Infections here.

Dr. Elaine Abrams of the Mailman School of Public Health at Columbia University said the new findings were “likely to have an enormous impact in this field and inform guidelines and recommendations from the World Health Organization.”

For infected mothers who have to breast feed because they live where water is contaminated, the health organization now recommends weaning as soon as a safe and acceptable replacement feeding is available.

Despite ample documentation of the cost effectiveness and lifesaving benefits of single-dose therapy with the antiretroviral drug nevirapine, economic and logistical reasons have limited its use in many developing countries.

Additional studies will be needed to determine the cost effectiveness of longer-term therapy.

“Breast feeding has proved to be a major stumbling block in preventing further H.I.V. transmissions from mother to child,” said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases.

If independent analyses of the findings from the new studies hold up, as expected, they “could serve as the basis of a new standard of care,” Dr. Fauci said in an interview here.

“The next series of studies will need to determine the optimal time for treating mothers and infants,” said Dr. Fauci. whose agency paid for the fifth breast-feeding study.

The studies reported here evaluated regimens and the potential of drug resistance among mothers and babies in India and African countries.

In a study in the Kisumu area of Kenya, along Lake Victoria, infected mothers took a combination of antiretrovirals from the 34th week of pregnancy and for the first six months of breast feeding their children. The newborns were given the standard single dose of nevirapine to prevent H.I.V. infection that might have occurred in delivery.

Of 497 newborns, 12, or 2.4 percent, were infected by the end of the first week of life, from infection in the womb or at birth. An additional 15 infants, or 3 percent, became infected 8 days to 12 months from breast feeding.

In a study in Blantyre, Malawi, more than 3,000 infants received one of three regimens of antiretrovirals for the first 14 weeks of life. After nine months of observation, the group that received nevirapine for 14 weeks had the lowest percent of infected infants, 3.1 percent. That compared with 10 percent among the control group, which received one dose of nevirapine and one week of another antiretroviral, AZT.

Another part of the Kisumu study showed that most of the infants infected in the first six months of life showed laboratory evidence of genetic resistance to the antiretroviral drugs in the study. But the authors cautioned that the finding did not mean that the drugs would necessarily fail in treating the infants.