February 13, 2003
The concentration of drug-resistant virus in breast milk was significantly higher than levels detected in the blood, Dr. E. Lee of Stanford University in Palo Alto reported Wednesday at the 10th Conference on Retroviruses and Opportunistic Infections in Boston.
Lee and colleagues at Stanford and at the University of Zimbabwe-Harare followed HIV-infected women in Chitungwiza, Zimbabwe, who participated in a study in which they received a single dose of nevirapine at the onset of labor. The women were subsequently monitored for HIV levels in plasma and breast milk at two, eight, 16 and 20 weeks after delivery. Complete information was available for plasma samples and breast milk samples for 33 and 20 women, respectively.
After eight weeks, mutations in breast milk associated with nevirapine resistance were detected in 13 of the 20 women (65 percent), while such mutations were found in plasma in eight of the 33 women (40 percent). Four infants had confirmed HIV infection. The most common mutation the researchers found is known to confer resistance to other drugs in the same class as nevirapine, non-nucleoside reverse transcriptase inhibitors.
Dr. Constance A. Benson of the University of Colorado Health Science Center in Denver, who did not participate in the study, said the findings do not warrant a change in policy. In settings where health care resources are scarce, she explained, the benefits of giving laboring HIV-positive women nevirapine to prevent their baby from becoming infected probably still outweigh the risks.