Abstract
The risk of postnatal HIV transmission exists throughout the breastfeeding period. HIV shedding in breast milk beyond six months has not been studied extensively. The aim of this study was to determine prevalence and determinants of HIV shedding in breast milk during continued breastfeedingA cross-sectional study was nested in the PROMISE-PEP trial in Lusaka, Zambia to analyze breast milk samples collected from both breasts at week 38 post-partum (mid-way during continued breastfeeding). We measured concurrent HIV deoxyribonucleic acid (DNA) and HIV ribonucleic acid (RNA) as proxies for cell-associated HIV (CAV) and cell-free HIV (CFV) shedding in breast milk respectively. Participants’ socio-demographic date, concurrent blood test results, sub clinical mastitis test results and contraceptive use data were available. Logistic regression models were used to identify determinants of HIV shedding in breast milk (detecting either CAV or CFV).The prevalence of HIV shedding in breast milk at 9 months post-partum was 79.4% (95%CI: 74.0 – 84.0). CAV only, CFV only and both CAV and CFV were detectable in 13.7%, 17.3% and 48.4% mothers, respectively. The odds of shedding HIV in breast milk decreased significantly with current use of combined oral contraceptives (AOR: 0.37; 95%CI: 0.17 – 0.83) and increased significantly with low CD4 count (AOR: 3.47; 95%CI: 1.23 – 9.80), unsuppressed plasma viral load (AOR: 6.27; 95%CI: 2.47 – 15.96) and severe sub-clinical mastitis (AOR: 12.56; 95%CI: 2.48 – 63.58).This study estimated that about 80% of HIV infected mothers not on ART shed HIV in breast milk during continued breastfeeding. Major factors driving this shedding were low CD4 count, unsuppressed plasma viral load and severe sub-clinical mastitis. The inverse relationship between breast milk HIV and use of combined oral contraceptives needs further clarification. Continued shedding of CAV may contribute to residual postnatal transmission of HIV in mothers on successful ART.
Highlights
National health authorities in Zambia principally promote and support breastfeeding and antiretroviral therapy (ART) as the strategy that will most likely give infants born to HIV infected mothers the greatest chance of HIV-free survival.[1]
Of the 315 mothers who were still breastfeeding at week 38, 270 had breast milk samples from both breasts stored at À80oC and eligible to participate in this study
Our results indicate that 79.4% (95%confidence interval (CI): 74.0 – 84.0) of HIV infected mothers shed HIV in breast milk in the absence of ART during continued breastfeeding
Summary
National health authorities in Zambia principally promote and support breastfeeding and antiretroviral therapy (ART) as the strategy that will most likely give infants born to HIV infected mothers the greatest chance of HIV-free survival.[1] The country has adopted the World Health Organization (WHO) recommendations to exclusively breastfeeding (EBF) for the first six months and continued breastfeeding with supplementary foods up to one year. Thereafter, extended breastfeeding until a safe and nutritionally adequate diet can be provided for the infant.[2] This is because EBF covers all nutritional and immunological requirements of the newborn baby[3] and both EBF and maternal ART promotes child survival.[4,5]. CFV in breast milk originates partly from HIV replication in infected lymphocytes and macrophages resident in mammary glands and partly from continued seeding of systemic HIV particles across the mammary epithelial layer.[6,14,15] CAV arise from local infections of mammary gland permissive cells and recruitment of HIV infected cells migrating from inducing sites of the mucosal immune system into the mammary gland and subsequently in breast milk.[6,15] The mean concentration of CAV per 106 BMC is lowest in colostrum[7] and is thought to increase over time even in the presence of ART.[11,12]
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