HIV Breast Milk Risk
Highest In Early Months

NEW YORK (Reuters Health)- The risk of an HIV-positive mother passing the virus to her infant via breast milk is highest in the first few months of life, according to a study conducted in the African nation of Malawi.
The researchers also found evidence that inexperienced mothers may be at higher risk for transmitting the virus through breastfeeding than mothers who have other children.
In the new study, published in the August 25th issue of The Journal of the American Medical Association, researchers led by Dr. Paolo Miotti (affiliated with Johns Hopkins University, Baltimore, at the time of the study) examined the HIV status of nearly 700 infants born to HIV-positive women living in Malawi, a developing nation in southern Africa. All of the infants were HIV-negative at time of birth.
While they observed that the cumulative infection rate increased over time, incidence of HIV infection was higher during the first 5 months of life. "Incidence per month was 0.7% during age 1 to 5 months, 0.6% during age 6 to 11 months, and 0.3% during age 12 to 17 months,'' they write.
According to the investigators, their study suggests that ''(the average) uninfected infant breastfed by an HIV-positive mother for 23 months had at least a 10.3% risk of becoming infected.'' Risks appeared to be highest "in the first half-year of life, when breastfeeding is particularly important,'' they add.
"Early weaning has been proposed as one possible strategy to limit HIV transmission through breast milk,'' Miotti commented in a press release. "Although discontinuing breastfeeding after 6 months would have prevented half of the HIV infections seen in our study, such an approach would increase the risk for illness and death from the respiratory and diarrheal diseases that antibodies and other factors in breast milk help protect against.''
In their report, Miotti's team also notes that women who had four or more previous children and those who were older were less likely to transmit HIV via breastfeeding than younger mothers or those with fewer children. The finding supports a theory that "mothers who are less experienced with breastfeeding are more likely to have (symptomless) mastitis and thereby a higher HIV transmission rate,'' they write.
The study findings "indicate that the incidence of transmissibility is clearly greater during the early months of breastfeeding than the later months,'' Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID) in Bethesda, Maryland, told Reuters Health.
"The contribution of this study is that it gives us a better handle on the timing of breastfeeding-transmitted HIV,'' Fauci added. However, the findings do not "lead to an easy strategy.''
For example, some people have suggested that weaning babies as quickly as possible may reduce the risk, he explained. However, this strategy was proposed with the assumption that the transmissibility of HIV is constant throughout the breastfeeding period, Fauci explained. Therefore, the new findings do not provide any easy prevention strategies for HIV transmission through breastfeeding.
Fauci added that the NIAID is now sponsoring trials to investigate whether affordable, inexpensive drugs, or a single-dose of a drug, such as nevirapine, administered to infants during the early phase of breastfeeding, can decrease the incidence of this type of HIV transmission.
The Joint United Nations Programme on HIV/AIDS currently recommends that all HIV-positive mothers be informed of the pros and cons of breastfeeding, and then be "supported in their choice'' by medical staff.
SOURCE: The Journal of the American Medical Association 1999;282:744-749, 781-783.