A recent PLOS published article reports that non-exclusive breastfeeding (EBF) more than doubles the risk of early postnatal HIV transmission in children of HIV-infected women.^[1] Non-exclusive breastfeeding is defined was defined as giving the child non-human milk, semi-solids or non-milk liquids, such as water in addition to the mothers milk.

The study looked at 958 HIV-infected women and their infants in Lusaka, Zambia. All were encouraged to breastfeed exclusively to 4 months. Single-dose nevirapine, an antiretroviral ^[2], was provided to prevent transmission. The adoption of EBF was high with 84% of women reporting only EBF cumulatively to 4 months.

Why Does This Work?

Of particular interest was the discussion of why this method should reduce HIV transmission. At first glance, it seems counter to what would be expected.

Discussions of possible mechanisms underlying the benefits of EBF for HIV transmission have focused on inflammation or activation within the infant gut as a result of the introduction of foreign antigens, contaminants and pathogens. We speculate that there may be additional processes including elevations in breast milk vial load as a result of decreased frequency of infant suckling. Since the frequency of milk removal dictates the rate of milk secretion ^[3], small changes, such as a missed feed or an irritable infant not suckling as much as usual, may result in some milk stasis (breast engorgement). If not reversed within a short period of time, epithelial permeability may increase (leaky tight junctions), allowing more efficient paracellular transfer of both cell-free and cell-associated HIV ^[4]. In a prior report, we demonstrated that breast milk HIV RNA concentrations increased dramatically following abrupt weaning ^[5]. We also reported here, intriguingly, that irregular, rather than regular, use of non-breast milk items was associated with stronger associations with transmission. We speculate that the shifts in breast feeding frequency that occur with non-EBF, particularly if it is irregular, may disrupt the efficiency of milk removal and may increase the infectivity of breast milk.

Further Research Critical

The results of this study of reduced HIV transmission with EBF are consistent with at least three other large African studies. ^[6]. ^[7], ^[8]. Such a low cost and sustainable intervention has major public health implications and it is critical that further research be undertaken so that safe and effective programs can be implemented in low-resource settings. The authors conclude by recommending strengthening breastfeeding support programs in pre-birth, maternity and well-baby services in the general population in order to benefit uninfected mothers and their children also.

References

1. Kuhn L, Sinkala M, Kankasa C, Semrau K, Kasonde P, et al. (2007) High Uptake of Exclusive Breastfeeding and Reduced Early Post-Natal HIV Transmission. PLoS ONE 2(12): e1363. doi:10.1371/journal.pone.0001363

2. Viramune® (nevirapine) tablets; Viramune® (nevirapine) oral suspension prescribing information (pdf)

3. Neville MC (1990) The physiological basis of milk secretion. Ann NY Acad Sci 586: 111.

4. Semba RD, Kumwenda N, Hoover DR, Taha TE, Quinn TC, Mtimavalye L, Biggar RJ, Broadhead R, Miotti PG, Sokoll LJ, van der HL, Chiphangwi JD (1999) Human immunodeficiency virus load in breast milk, mastitis, and mother-to-child transmission of human immunodeficiency virus type 1. J Infect Dis 180: 9398.

5. Thea DM, Aldrovandi G, Kankasa C, Kasonde P, Decker WD, Semrau K, Sinkala M, Kuhn L (2006) Post-weaning breast milk HIV-1 viral load, blood prolactin levels and breast milk volume. AIDS 20: 15391547.

6. Coutsoudis A, Pillay K, Spooner E, Kuhn L, Coovadia HM (1999) Influence of infant feeding patterns on early mother-to-child transmission of HIV-1 in Durban, South Africa. Lancet 354: 471476.

7. Iliff P, Piwoz E, Tavengwa N, Zunguza C, Marinda E, Nathoo K, Moulton L, Ward B, Humphrey J (2005) Early exclusive breastfeeding reduces the risk of postnatal HIV-1 transmission and increases HIV-free survival. AIDS 19: 699708.

8. Coovadia HM, Rollins NC, Bland RM, Little K, Coutsoudis A, Bennish ML, Newell ML (2007) Mother-to-child transmission of HIV-1 infection during exclusive breastfeeding in the first 6 months of life: an intervention cohort study. Lancet 369: 11071116.

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