Daniel M. Keller, PhD

September 29, 2011

September 29, 2011 (Chicago, Illinois) — Giving HIV-positive mothers lopinavir/ritonavir (LPV/r)-based highly active antiretroviral therapy (HAART) before delivery and continuing treatment for 12 months afterward appeared to largely prevent the transmission of HIV to infants during periods of exclusive breastfeeding and then breastfeeding supplemented with other foods.

This study, reported here at the 51st Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), is the first to demonstrate this finding, announced investigator Michael Silverman, MD, assistant professor at the University of Toronto, Ontario, Canada.

The study findings support new World Health Organization (WHO) guidelines.

In the past, short regimens of inexpensive drugs were given to mothers around the time of delivery, which reduced the risk for transmission of HIV to the newborn by about 50%. However, transmission through breastfeeding, which could not be avoided because of the absence of safe water supplies for formula feeding, remained a problem.

Breastfeeding exclusively for the first 6 months provided infants with all needed nutrition. But when breast milk was supplemented with other needed foods or liquids as the child developed past 6 months ("complementary feeding"), the risk for HIV transmission rose. The WHO previously recommended exclusive breastfeeding for the first 6 months, and then rapid weaning. However, early weaning led to malnutrition and higher mortality, so that any gains from preventing HIV transmission were offset by more deaths from malnutrition.

Recently updated WHO recommendations now advise that HIV-seropositive mothers in developing countries receive HAART, that they exclusively breastfeed for 6 months, that they begin complementary feeding while still nursing, and that they fully wean the child at 12 months. The mother should be receiving HAART or the baby should be receiving nevirapine this entire time.

The goal is to avoid the danger of formula feeding and the risks for diarrhea while allowing the infant to get the nutritional and social benefits of breastfeeding but avoiding transmission of HIV.

The study authors note that such a plan also prevents the social stigma and ostracism that can result from a mother using formula, because "in most African countries, the only reason a woman would formula-feed is if she were HIV-positive."

Investigators in Lusaka, Zambia, carried out a pilot program in which HIV-positive pregnant women received HAART (zidovudine/lamivudine 400 mg and LPV/r 100 mg) twice daily antepartum and for 12 months postpartum. The women breastfed according to the latest WHO recommendations. Infant HIV status was assessed by testing dried blood spots for HIV using polymerase chain reaction.

The study initially enrolled 279 women, 225 of whom delivered 230 live infants, with 9 stillbirths. Eighty-five women did not complete the study for various reasons (dropped out, lost to follow-up, maternal death, stillbirths, or infant death).

Of the 194 evaluable mother/infant pairs, 3 infants (1.5%) were HIV-positive by 6 weeks of age, 2 of 99 (2.0%) became positive between 6 weeks and 12 months of age, and 1 of 49 (2.0%) became positive after 12 months.

In the case of the 2 infants who became HIV-positive between 6 weeks and 12 months, both mothers had stopped the medications on their own. In the case of the 1 baby who contracted HIV after 12 months, the mother had stopped her medications but continued breastfeeding.

This study is the first to demonstrate that LPV/r-based HAART can prevent HIV transmission during the period of exclusive breastfeeding in the first 6 months of an infant's life and during complementary feeding in the second 6 months of life.

Grace John-Stewart, MD, MPH, PhD, professor of medicine, epidemiology, global health, and pediatrics at the University of Washington in Seattle, told Medscape Medical News that previous studies have shown that HIV transmission risk is substantially decreased with either HAART or infant prophylaxis with nevirapine.

"However, previous studies were limited to 6 months of breastfeeding," Dr. John-Stewart emphasized. "WHO guidelines recommend 12 months, so the new study provides evidence that antiretrovirals decrease transmission during extended breastfeeding," she said.

Dr. John-Stewart added that the rates of transmission are similar to infant prophylaxis studies, so either approach can be effective. She suggested following the babies longer to look for other effects of the treatment, such as hematologic abnormalities.

Dr. John-Stewart sees the new WHO guidelines as especially relevant for places with poor-quality water supplies.

Abbott pharmaceuticals provided medications and financial support for the study. Dr. Silverman reports receiving honoraria from Merck and Bristol-Myers Squibb as a speaker, research support from Abbott, and consulting fees from Vertex as a scientific advisor. Dr. John-Stewart has disclosed no relevant financial relationships.

51st Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC): Abstract H1-1153. Presented September 19, 2011.

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