July 25 (Bloomberg) -- Breastfed babies who took daily HIV treatments for six weeks cut their risk of getting the AIDS virus from their infected mothers by 15 percent, according to a study that has sparked disagreement among the authors.

Boehringer-Ingelheim GmbH's Viramune often is given at birth to help babies block transmission of HIV from their mothers. Three members of a global research team argued against the study's findings that extending the babies' daily treatment for six weeks reduced risks of infection by 46 percent.

The debate may undermine growing evidence that extended treatment with the drug, also called nevirapine, cuts infection risk from breastfeeding. Breastfeeding led to about 150,000 infant cases of the virus last year, mainly in low-income areas. More than 80 percent of all HIV-infected mothers are in sub- Saharan Africa and Asia.

``A longer course of daily infant nevirapine to prevent HIV transmission via breast milk might be more effective where access to affordable and safe replacement feedings isn't yet available,'' said Robert Bollinger of the Johns Hopkins School of Medicine in Baltimore, lead author of the study published today in the Lancet.

The study of 2,024 babies in Ethiopia, India and Uganda, showed that extended Viramune treatment reduced infections over the six weeks of treatment. However, it didn't meet the main goal, which was to reduce transmission for six months, said three members of the research team led by Mrudula Phadke of the Maharshtra University of Health Sciences in Nashik, India, in a letter to the journal.

Side Effects

``It is wrong that a drug that has not shown significant benefit and which has serious toxic side effects in 38.4 percent of babies should be tried for longer,'' they wrote in a letter accompanying the study. Side effects included rashes, low immune cell counts, and low levels of certain enzymes.

The study's design of six months was based on the 10 to 14 days that it takes nevirapine to build up in babies' blood, the three researchers said in their letter. The finding that infections were lower after six weeks ``does not reflect the effect of six weeks of treatment at all,'' they said.

Rather than using potentially toxic treatments, HIV experts should focus on ways to make infant formula more available and acceptable to infected breastfeeding women in poorer countries, the Indian scientists said.

About 25,000 researchers, caregivers and advocates are scheduled to gather beginning Aug. 3 in Mexico City for the biennial International AIDS Conference, the world's biggest meeting on the disease.

Formula Expensive

In developed countries, HIV-infected mothers generally avoid breastfeeding. In developing countries, infant formula is too costly for most families; using it can lead others to suspect a woman is HIV-infected, which is unacceptable in many societies.

HIV-prevention gains made by breastfeeding avoidance or early weaning are largely offset by an increased risk of death from diarrhea, pneumonia and malnutrition, The Lancet said in an editorial. An infected mother often faces a difficult choice: breastfeed and risk HIV transmission, or not breastfeed and risk the baby dying from another cause.

``Extended infant prophylaxis with nevirapine is simple enough to be implemented almost anywhere,'' Jeffrey Stringer and Benjamin Chi from the University of Alabama at Birmingham, said in a comment. ``It represents a long-awaited, if partial, solution to a mother's impossible choice. We should not delay.''

Zambian Study

A study in the New England Journal of Medicine last month said nursing babies in Zambia who took Viramune for an extra 14 weeks after the standard initial dose cut the risk of infection by about 50 percent. Studies presented at the February Conference on Retroviruses and Opportunistic Infections in Boston also showed the drug cuts HIV risk during breastfeeding.

The dispute among the paper's authors is unusual, Lancet editors Pia Pini and Sabine Kleinert said in a written commentary. The U.S. National Institutes of Health, which funded the study, said there was no ``breach of research integrity,'' the commentary said.

``In our opinion, publication of these important data, with complete disclosure, is the best course of action,'' the editors said.

The U.S. National Institute of Allergy and Infectious Diseases and the Fogarty International Center also funded the study.

To contact the reporter on this story: Chantal Britt at cbritt@bloomberg.net.

Last Updated: July 24, 2008 19:00 EDT