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Postnatal Transmission of HIV and Breast Milk Viral Load and Sodium Level during the First 4 Months of Breastfeeding
Katherine Semrau*1, M Ghosh2, C Kankasa3, M Sinkala4, P Kasonde3, M Mwiya3, D Thea1, L Kuhn5, and G Aldrovandi2
1Boston Univ, MA, US; 2Univ of Southern California, Los Angeles, US; 3Univ Teaching Hosp, Univ of Zambia, Lusaka; 4Ministry of Hlth, Lusaka, Zambia; and 5Columbia Univ Mailman Sch of Publ Hlth, New York, NY, US
Background: To better understand the temporal and lateral
dynamics of HIV shedding in breast milk and transmission of HIV (mother-to-child
transmission [MTCT]), we examined the relationship between breast milk HIV RNA
levels, breast milk sodium (Na; a marker of epithelial permeability), and MTCT.
Methods: Patterns of HIV shedding and Na
concentration were examined in breast milk samples taken over the first 4
months of breastfeeding in 138 HIV+ women participating in the
Zambia Exclusive Breast Feeding Study, Lusaka, Zambia. By HIV-1 DNA polymerase chain reaction (PCR)
of heel-stick samples, 32 (23.2%) children tested positive. Maternal plasma
viral load and CD4 count were measured at study enrollment. Breast milk viral
load and breast milk Na were measured at 1 week, 1 month, and 4 months
post-partum. Categorical variables were compared with χ2 test;
continuous measures were compared with a Kruskal-Wallis test and generalized
estimating equations were used for repeated measures.
Results: Breast milk viral load in the right and left
breast were correlated at all time points (1 week: ρ = 0.78, p <0.0001; 1 month:
ρ = 0.75, p <0.0001; 4
months: ρ = 0.88, p <0.0001). Detectable breast milk
viral load (≥50 copies/mL) in both breasts was found in 35% of women at 1
week, 57% at 1 month, and 65% at 4 months. At each time point, 39% of women had
consistently detectable viral load and a significantly higher risk of MTCT than
women who were either inconsistent or non-shedders (OR = 4.3, 95%CI 2.04 to
9.44). Breast milk Na levels correlated across breasts at each visit (1
week: ρ = 0.29, p = 0.003; 1 month: ρ = 0.35, p =0.003; 4 months: ρ =
0.42, p <0.0001), and elevated
levels (≥13 mM/L) were detected in 41% at 1 week, 20% at 1 month, and 7%
at 4 month. Elevated breast milk Na at 4
months was associated with MTCT (p =
0.005), maternal CD4 count <200 cells/µL (p = 0.001), and maternal viral load (≥100,000 copies/mL) (p = 0.034). Elevated Na concentration at
1 week post-partum was common and was not associated with any of these
parameters.
Conclusions: Consistent viral shedding and high breast
milk viral load are strong predictors of MTCT. While increased sodium
concentrations later in breastfeeding correlate with breast milk viral load and
maternal HIV indicators and are predictive of HIV transmission, increased
breast milk Na appears to be normal in early lactation and is not predictive of
MTCT.
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