Mother-to-Child Transmission of Arboviruses during Breastfeeding: From Epidemiology to Cellular Mechanisms.

Most viruses use several entry sites and modes of transmission to infect their host (parenteral, sexual, respiratory, oro-fecal, transplacental, transcutaneous, etc.). Some of them are known to be essentially transmitted via arthropod bites (mosquitoes, ticks, phlebotomes, sandflies, etc.), and are thus named arthropod-borne viruses, or arboviruses. During the last decades, several arboviruses have emerged or re-emerged in different countries in the form of notable outbreaks, resulting in a growing interest from scientific and medical communities as well as an increase in epidemiological studies. These studies have highlighted the existence of other modes of transmission. Among them, mother-to-child transmission (MTCT) during breastfeeding was highlighted for the vaccine strain of yellow fever virus (YFV) and Zika virus (ZIKV), and suggested for other arboviruses such as Chikungunya virus (CHIKV), dengue virus (DENV), and West Nile virus (WNV). In this review, we summarize all epidemiological and clinical clues that suggest the existence of breastfeeding as a neglected route for MTCT of arboviruses and we decipher some of the mechanisms that chronologically occur during MTCT via breastfeeding by focusing on ZIKV transmission process.

Breastfeeding and COVID-19.

The coronavirus disease 2019 (COVID-19) pandemic has affected all dimensions of health care, including exclusive breastfeeding assurance and its promotion. The risk of contagion and the consequences of the pandemic have raised concerns among future mothers or in those who are already breastfeeding due to the risk of possible transmission of the virus through breast milk, although active severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has not yet been detected in breast milk. The fear of contagion has favored mother-child isolation policies. So far, there is no evidence of vertical transmission, and the risk of horizontal transmission in the infant is similar to that of the general population. In infants with COVID-19, breastfeeding can even favorably change the clinical course of the disease.

La pandemia de enfermedad por coronavirus 2019 (COVID-19) ha afectado a todas las dimensiones de la atención en salud, entre ellas el aseguramiento de la lactancia materna exclusiva y su promoción. El riesgo de contagio y las consecuencias de la pandemia han provocado preocupación entre las futuras madres o las que se ya encuentran lactando debido al riesgo de una posible transmisión del virus a través de la leche materna. Aunque aún no se ha detectado el coronavirus 2 del síndrome respiratorio agudo grave (SARS-CoV-2) activo en la leche materna. El miedo al contagio ha favorecido las políticas de aislamiento madre-hijo. Hasta el momento no existe evidencia de transmisión vertical y el riesgo de transmisión horizontal en el lactante es similar al de la población general. En lactantes con COVID-19 la lactancia materna incluso puede cambiar favorablemente el curso clínico de la enfermedad.

Eliminating postnatal HIV transmission in high incidence areas: need for complementary biomedical interventions.

The rate of mother-to-child transmission (MTCT) of HIV from breastfeeding is increasing relative to other causes of MTCT. Early effective preconception and antenatal antiretroviral therapy (ART) reduces intrauterine and intrapartum MTCT, whereas maternal post-partum HIV acquisition, untreated maternal HIV, and suboptimal postnatal maternal ART adherence increase the risk of MTCT through breastfeeding. Although the absolute number of cases of MTCT acquired through breastfeeding is decreasing, the rate of decrease is less than the decrease in intrauterine and intrapartum MTCT. Unless current strategies are universally applied, they might not be sufficient to eliminate MTCT due to breastfeeding. Urgent action is needed to evaluate and implement additional preventive biomedical strategies in high HIV prevalence and incidence settings to eliminate MTCT from breastfeeding. Preventive strategies include: pre-exposure prophylaxis in breastfeeding women who have an increased risk of acquiring HIV; postnatal reinforcement strategies, such as maternal retesting for HIV, maternal care reinforcement, and prophylaxis in infants exposed to HIV via breastmilk; and active (vaccine) or passive immunoprophylaxis with long-acting broadly neutralising antibodies.

Lactancia materna y COVID-19 / Breastfeeding and COVID-19

Resumen La pandemia de enfermedad por coronavirus 2019 (COVID-19) ha afectado a todas las dimensiones de la atención en salud, entre ellas el aseguramiento de la lactancia materna exclusiva y su promoción. El riesgo de contagio y las consecuencias de la pandemia han provocado preocupación entre las futuras madres o las que se ya encuentran lactando debido al riesgo de una posible transmisión del virus a través de la leche materna. Aunque aún no se ha detectado el coronavirus 2 del síndrome respiratorio agudo grave (SARS-CoV-2) activo en la leche materna. El miedo al contagio ha favorecido las políticas de aislamiento madre-hijo. Hasta el momento no existe evidencia de transmisión vertical y el riesgo de transmisión horizontal en el lactante es similar al de la población general. En lactantes con COVID-19 la lactancia materna incluso puede cambiar favorablemente el curso clínico de la enfermedad.

Abstract The COVID-19 pandemic has affected the health attention in all dimensions, one of them, the exclusive breastfeeding assurance and her promotion. The high risk of contagion and the pandemic consequences have raised a number of concerns in future mothers or those who are breastfeeding because of the risk of a possible transmission of the virus through breast milk. Although SARS-CoV2 has no evidence of being active on breast milk, the fear of contagion has favored mother-child isolation policies. At this point, there are no evidence of vertical transmission and the risk of horizontal transmission in the infant is similar to the general population. Breastfeeding in newborn with COVID-19, can even favorably change the clinical course of the disease.

Negative Transmission of SARS-CoV-2 to Hand-Expressed Colostrum from SARS-CoV-2-Positive Mothers.

Aim: The objective of our study was to determine whether the SARS-CoV-2-positive mothers transmit the virus to their hand-expressed colostrum. Methods: This is an observational prospective study that included pregnant women who tested positive for SARS-CoV-2 by PCR test on a nasopharyngeal swab at the moment of childbirth and who wanted to breastfeed their newborns. A colostrum sample was obtained from the mothers by manual self-extraction. To collect the samples, the mothers wore surgical masks, washed their hands with an 85% alcohol-based gel, and washed their breast with gauze that was saturated with soap and water. Results: We obtained seven colostrum samples from different mothers in the first hours postdelivery. SARS-CoV-2 was not detected in any of the colostrum samples obtained in our study. Conclusion: In our study, breast milk was not a source of SARS-CoV-2 transmission. Hand expression (assuring that a mask is used and that appropriate hygienic measures are used for the hands and the breast), when direct breastfeeding is not possible, appears to be a safe way of feeding newborns of mothers with COVID-19.

Differences in Breast Milk Composition of HIV-Infected and HIV-Uninfected Mothers of Premature Infants: Effects of Antiretroviral Therapy.

INTRODUCTION: A key strategy to prevent mother-to-child transmission of the human immunodeficiency virus (HIV) and to reduce infant morbidity and mortality includes providing the HIV-exposed premature infant with breast milk accompanied by dual anti-retroviral therapy (ART). The effects of HIV and ART on premature breast milk composition are largely unknown. The aim of the study was to assess and compare the breast milk composition of HIV-infected mothers receiving ART and HIV-uninfected mothers who gave birth to premature infants. MATERIALS AND METHODS: Lactating HIV-infected women receiving ART (n = 38) and HIV-uninfected women (n = 36) with premature infants provided two breast milk samples on days 7 and 9, respectively, of lactation. Breast milk samples were analyzed for total energy, protein, carbohydrates, fat, phosphate, iron, zinc, and copper content. RESULTS: Breast milk of HIV-infected women contained higher protein (1.95 versus 1.78 g/100 g; p = 0.04), fat (4.42 versus 3.49 g/100 g; p = 0.01), and copper (0.64 versus 0.56 mg/L; p = 0.02) levels; whereas carbohydrate (5.37 versus 6.67 g/100 g; p = 0.002) and zinc (5.26 versus 5.78 mg/L; p = 0.04) levels were lower compared with those of HIV-uninfected women. Zinc levels were significantly lower in HIV-infected women with early gestation periods, and the lowest levels were observed in women who received ART for ≤4 weeks (0.58 mg/L; p = 0.03). Total energy (78.22 versus 61.48 kCal/100 mL) and fat levels (5.39 versus 3.00 g/100 mL) were significantly higher in the late gestation period HIV-infected women. Copper levels (0.61 mg/L) were higher in the late gestation period women who received >4 weeks of ART exposure (p = 0.05). CONCLUSION: Differences existed in the breast milk composition of HIV-infected women on ART compared with HIV-uninfected women. ART exposure period may influence breast milk composition.

Increased Cytomegalovirus Secretion and Risks of Infant Infection by Breastfeeding Duration From Maternal Human Immunodeficiency Virus Positive Compared to Negative Mothers in Sub-Saharan Africa.

BACKGROUND: Breastfeeding imparts beneficial immune protection and nutrition to infants for healthy growth, but it is also a route for human immunodeficiency virus (HIV) and human cytomegalovirus (HCMV) infection. In previous studies, we showed that HCMV adversely affects infant development in Africa, particularly with maternal HIV exposure. In this study, we analyzed infants risks for acquisition of HCMV infection from breastfeeding and compared HIV-positive and HIV-negative mothers. METHODS: Two cohorts were studied in Zambia. (1) Two hundred sixty-one HIV-infected and HIV-uninfected mothers were compared for HCMV deoxyribonucleic acid (DNA) loads and genotypes (glycoprotein gO) in milk from birth to 4 months postpartum. (2) Maternally HIV-exposed and HIV-unexposed infants were compared for HCMV infection risk factors. The second cohort of 460 infants, from a trial of micronutrient-fortified complementary-food to breastfeeding, were studied between 6 and 18 months of age. Human cytomegalovirus seroprevalence was assayed, and logistic regression was used to calculate risk factors for HCMV infection, including maternal HIV exposure and breastfeeding duration. RESULTS: Human cytomegalovirus was detected in breast milk from 3 days to 4 months postpartum, with significantly raised levels in HIV-positive women and independent of genotype. In infants, HCMV antibody seroprevalence was 83% by 18 months age. Longer breastfeeding duration increased infection risk in maternally HIV-unexposed (odds ratio [OR] = 2.69 for 18 months vs <12 months; 95% confidence interval [CI], 0.84-8.59; P = .03) and HIV-exposed infants (OR = 20.37 for >6 months vs never; 95% CI, 3.71-111.70; P < .001). CONCLUSIONS: Prolonged breastfeeding, which is common in Africa, increased risk of HCMV infection in infants. Both HIV-positive and HIV-negative women had extended milk HCMV secretion. Women who were HIV-positive secreted higher HCMV levels, and for longer duration, with their children at increased infection risk. Human cytomegalovirus control is required to maintain health benefits of breastfeeding.

The function and affinity maturation of HIV-1 gp120-specific monoclonal antibodies derived from colostral B cells.

Despite the risk of transmitting HIV-1, mothers in resource-poor areas are encouraged to breastfeed their infants because of beneficial immunologic and nutritional factors in milk. Interestingly, in the absence of antiretroviral prophylaxis, the overwhelming majority of HIV-1-exposed, breastfeeding infants are naturally protected from infection. To understand the role of HIV-1 envelope (Env)-specific antibodies in breast milk in natural protection against infant virus transmission, we produced 19 HIV-1 Env-specific monoclonal antibodies (mAbs) isolated from colostrum B cells of HIV-1-infected mothers and investigated their specificity, evolution, and anti-HIV-1 functions. Despite the previously reported genetic compartmentalization and gp120-specific bias of colostrum HIV Env-specific B cells, the colostrum Env-specific mAbs described here demonstrated a broad range of gp120 epitope specificities and functions, including inhibition of epithelial cell binding and dendritic cell-mediated virus transfer, neutralization, and antibody-dependent cellular cytotoxicity. We also identified divergent patterns of colostrum Env-specific B-cell lineage evolution with respect to crossreactivity to gastrointestinal commensal bacteria, indicating that commensal bacterial antigens play a role in shaping the local breast milk immunoglobulin G (IgG) repertoire. Maternal vaccine strategies to specifically target this breast milk B-cell population may be necessary to achieve safe breastfeeding for all HIV-1-exposed infants.

Effect of selenium supplementation on HIV-1 RNA detection in breast milk of Tanzanian women.

OBJECTIVE: Selenium supplementation for women infected with HIV may increase genital shedding of HIV-1, however, to our knowledge, no studies have examined the effect on viral shedding in breast milk. The aim of this study was to determine the effect of selenium supplementation on HIV-1 RNA detection in breast milk of HIV-infected women. METHODS: HIV-infected pregnant women enrolled at 12 to 27 wk gestation in a randomized, double-blind, placebo-controlled trial of daily selenium (200 µg as selenomethionine) had cell-free HIV-1 RNA quantified in breast milk at 4 to 9 wk postpartum. All participants received high-dose multivitamins containing vitamin B complex, C, and E as standard of care. RESULTS: The proportion of women with detectable (>50 copies/mL) HIV-1 RNA in breast milk appeared to be increased in the selenium group (36.4%) compared with those in the placebo group (27.5%) among the total cohort (N = 420), but results were borderline statistically significant (relative risk [RR], 1.32; 95% confidence interval [CI], 1.00-1.76; P = 0.05). In secondary analyses, the proportion of women with detectable HIV-1 RNA in breast milk was significantly greater in the selenium group (37.8%) compared with placebo group (27.5%) among women who did not receive highly active antiretroviral therapy (HAART; RR, 1.37; 95% CI, 1.03-1.82; P = 0.03). This relationship was primarily due to a significant effect of selenium among primiparous women (RR, 2.24; 95% CI, 1.30-3.86; P < 0.01), but not multiparous women (RR, 1.14; 95% CI, 0.81-1.59; P = 0.54) (P-value for interaction = 0.02). Too few women received HAART in this study (n = 12) to establish the effect of selenium supplementation. CONCLUSIONS: Selenium supplementation appears to increase HIV-1 RNA detection in breast milk among primiparous women not receiving HAART. Safety studies among pregnant women on HAART need to be conducted before administering selenium-containing supplements.

Effect of flash-heat treatment on antimicrobial activity of breastmilk.

BACKGROUND AND OBJECTIVES: The World Health Organization recommends human immunodeficiency virus (HIV)-positive mothers in resource-poor regions heat-treat expressed breastmilk during periods of increased maternal-to-child transmission risk. Flash-heat, a "low tech" pasteurization method, inactivates HIV, but effects on milk protein bioactivity are unknown. The objectives were to measure flash-heat's effect on antimicrobial properties of lactoferrin, lysozyme, and whole milk and on the digestive resistance of lactoferrin and lysozyme. METHODS: Flash-heated and unheated breastmilk aliquots from HIV-positive mothers in South Africa were "spiked" with Staphylococcus aureus and Escherichia coli and then cultured for 0, 3, and 6 hours. Lysozyme and lactoferrin activities were determined by lysis of Micrococcus luteus cells and inhibition of enteropathogenic E. coli, respectively, measured spectrophotometrically. Percentages of proteins surviving in vitro digestion, lactoferrin and lysozyme activity, and bacteriostatic activity of whole milk in heated versus unheated samples were compared. RESULTS: There was no difference in rate of growth of E. coli or S. aureus in flash-heated versus unheated whole milk (p = 0.61 and p = 0.96, respectively). Mean (95% confidence interval) antibacterial activity of lactoferrin was diminished 11.1% (7.8%, 14.3%) and that of lysozyme by up to 56.6% (47.1%, 64.5%) by flash-heat. Digestion of lysozyme was unaffected (p = 0.12), but 25.4% less lactoferrin survived digestion (p < 0.0001). CONCLUSIONS: In summary, flash-heat resulted in minimally decreased lactoferrin and moderately decreased lysozyme bioactivity, but bacteriostatic activity of whole milk against representative bacteria was unaffected. This suggests flash-heated breastmilk likely has a similar profile of resistance to bacterial contamination as that of unheated milk. Clinical significance of the decreased bioactivity should be tested in clinical trials.

Effect of vitamin supplements on HIV shedding in breast milk.

BACKGROUND: Supplementation in lactating HIV-1-infected women with preformed vitamin A and ß-carotene (VA/BC) increases the risk of mother-to-child transmission of HIV through breastfeeding. Identifying a biological mechanism to explain this unexpected finding would lend support to a causal effect. OBJECTIVE: The aim of the study was to evaluate the effect of VA/BC or multivitamin (B complex, vitamin C, and vitamin E) supplementation of HIV-infected women on HIV shedding in breast milk during the first 2 y postpartum. DESIGN: We quantified viral (cell-free) and proviral (cell-associated) HIV loads in breast-milk samples collected ≤15 d after delivery and every 3 mo thereafter from 594 Tanzanian HIV-1-infected women who participated in a randomized trial. Women received 1 of the following 4 daily oral regimens in a 2 × 2 factorial fashion during pregnancy and throughout the first 2 y postpartum: multivitamin, VA/BC, multivitamin including VA/BC, or placebo. RESULTS: The proportion of breast-milk samples with detectable viral load was significantly higher in women who received VA/BC (51.3%) than in women who were not assigned to VA/BC (44.8%; P = 0.02). The effect was apparent ≥6 mo postpartum (relative risk: 1.34; 95% CI: 1.04, 1.73). No associations with proviral load were observed. The multivitamin had no effects. In observational analyses, ß-carotene but not retinol breast-milk concentrations were significantly associated with an increased viral load in milk. CONCLUSIONS: VA/BC supplementation in lactating women increases the HIV load in breast milk. This finding contributes to explaining the adverse effect of VA/BC on mother-to-child transmission. ß-Carotene appears to have an effect on breast-milk viral load, independent of preformed vitamin A. This trial was registered at clinicaltrials.gov as NCT00197756.

Transformation of breast milk macrophages by HTLV-I: implications for HTLV-I transmission via breastfeeding.

Human T cell leukemia virus type I (HTLV-I), a causative agent of adult T-cell leukemia (ATL), is transmitted from mother to child predominantly by breastfeeding. The source of HTLV-I-infected cells in breast milk has been thought to be T cells, however, the majority of cells in breast milk are CD14(+) macrophages but not CD3(+) T lymphocytes, and no data are available regarding HTLV-I transmission through breast milk macrophages (BrMMpsi). To explore the potential of BrMMpsi as a possible source of infection in mother to child transmission (MTCT) of HTLV-I, an immortalized cell line (HTLV-BrMMpsi) has been established from BrMMpsi by infection with HTLV-I. HTLV-BrMMpsi retained macrophage characteristics and did not express a complete dendritic cell (DC) phenotype; nevertheless, HTLV-BrMMpsi efficiently promoted T cell proliferation in primary allogeneic mixed lymphocyte reaction (MLR) like DC. Moreover, HTLV-I infection could be transmitted from HTLV-BrMMpsi to activated T cells in the peripheral blood. These findings suggested that BrMMpsi might be an appropriate HTLV-I reservoir involved in MTCT transmission via breastfeeding.

Interventions for preventing late postnatal mother-to-child transmission of HIV.

BACKGROUND: Worldwide, mother-to-child transmission (MTCT) of human immunodeficiency virus type 1 (HIV) represents the most common means by which children acquire HIV infection. Efficacious and effective interventions to prevent in utero and intrapartum transmission of HIV infection have been developed and implemented. However, a large proportion of MTCT of HIV occurs postnatally, through breast milk transmission. OBJECTIVES: The objectives of this systematic review were to collate and assess the evidence regarding interventions to decrease late postnatal MTCT of HIV, and to determine the efficacy of such interventions in decreasing late postnatal MTCT of HIV, increasing overall survival, and increasing HIV-free survival. SEARCH STRATEGY: Electronic searches were undertaken using PubMed, EMBASE and other databases for 1980-2008. Hand searches of reference lists of pertinent reviews and studies, as well as abstracts from relevant conferences, were also conducted. Experts in the field were contacted to locate any other studies. The search strategy was iterative. SELECTION CRITERIA: Randomized clinical trials assessing the efficacy of interventions to prevent MTCT of HIV through breast milk were included in the analysis. Other trials and intervention cohort studies with relevant data also were included, but only when randomization was not feasible due to the nature of the intervention (i.e., infant feeding modality). DATA COLLECTION AND ANALYSIS: Data regarding HIV infection status and vital status of infants born to HIV-infected women, according to intervention, were extracted from the reports of the studies. MAIN RESULTS: Six randomized clinical trials and one intervention cohort study were included in this review. Two trials addressed the issue of shortening the duration of (or eliminating) exposure to breast milk. In a trial of breastfeeding versus formula feeding, formula feeding was efficacious in preventing MTCT of HIV (the cumulative probability of HIV infection at 24 months was 36.7% in the breastfeeding arm and 20.5% in the formula arm [p = 0.001]), but the mortality and malnutrition rates during the first two years of life were similar in the two groups. In a trial of early cessation of breastfeeding, HIV-free survival was similar between those children who ceased breastfeeding around four months of age and those who continued breastfeeding. Another trial addressing vitamin supplementation found more cases of HIV infection among children of mothers in the vitamin A arm. Efficacy for other vitamin supplements was not shown. An intervention cohort study evaluated the risk of MTCT according to infant feeding modality, and found increased risks of MTCT among breastfed children who also received solids (hazard ratio = 10.87, p = 0.018) as well as higher 3-month mortality rates (hazard ratio = 2.06) among infants given non- breast milk feedings (instead of exclusive breastfeeding). Three trials evaluated antiretroviral prophylaxis to breastfeeding infants. One trial found that breastfeeding with zidovudine prophylaxis (transmission rate = 9.0%) was not as effective as formula feeding (transmission rate 5.6%) in preventing late postnatal HIV transmission (p = 0.04). Breastfeeding with zidovudine prophylaxis and formula feeding had comparable HIV-free survival rates at 18 months (p = 0.60). Two trials of extended nevirapine prophylaxis demonstrated efficacy. In the first (data combined from trials conducted in three different countries), a six-week course of nevirapine resulted in a lower risk of HIV transmission by six weeks of age (p=0.009), but not at six months of age (p = 0.016). In the second, nevirapine administration until 14 weeks of age (5.2%) or nevirapine with zidovudine until 14 weeks of age (6.4%) resulted in significantly lower risks of MTCT of HIV by 9 months of age than a control regimen of peripartum prophylaxis (10.6%) (p < 0.001). HIV-free survival was significantly better through the age of 9 months in both extended prophylaxis groups, and through the age of 15 months in the extended nevirapine group. AUTHORS' CONCLUSIONS: Complete avoidance of breastfeeding is efficacious in preventing MTCT of HIV, but this intervention has significant associated morbidity (e.g., diarrheal morbidity if formula is prepared without clean water). If breastfeeding is initiated, two interventions 1). exclusive breastfeeding during the first few months of life; and 2) chronic antiretroviral prophylaxis to the infant (nevirapine alone, or nevirapine with zidovudine) are efficacious in preventing transmission.

Analysis of the presence of cutaneous and mucosal papillomavirus types in ductal lavage fluid, milk and colostrum to evaluate its role in breast carcinogenesis.

Several independent studies have presented evidence for the involvement of human papillomaviruses (HPV) in the aetiology of human breast cancer, while others have reported the opposite findings. Here, we have analysed by a high sensitive multiplex PCR-based method the prevalence of alpha mucosal and beta cutaneous HPV DNA in 90 ductal lavages, colostrum and milk. Ten of the 70 DLs analyzed (14%) contained a single or multiple beta HPV types, while DNA from mucosal high-risk HPV types was detected in only one sample (1/70). A strong reduction of HPV positivity in DL fluids was observed in 45 specimens collected after removal of the superficial layers of the nipple epidermis. All DLs were negative for the mucosal low-risk HPV types 6 and 11. Finally, HPV positivity was low in colostrum and milk. Our data show that DNA of alpha mucosa and beta cutaneous HPV types are rarely present in the breast fluids and suggest that a direct role of HPV in breast carcinogenesis is unlikely.

Subclinical mastitis, cell-associated HIV-1 shedding in breast milk, and breast-feeding transmission of HIV-1.

BACKGROUND: Mastitis has been identified as a risk factor for mother-to-child transmission (MTCT) of HIV-1 through breast-feeding. It is unclear whether this association is mediated by increased cell-free virus (CFV) versus cell-associated virus (CAV) HIV shedding in breast milk. METHODS: We examined the risk of MTCT associated with subclinical mastitis and the relation between mastitis and CFV or CAV shedding in breast milk. Fifty-nine women who transmitted HIV through breast-feeding (cases) were individually matched to 59 nontransmitting controls nested in a cohort from Tanzania. For each case, we selected a milk specimen obtained before the infant's first positive test to quantify sodium (Na) and potassium (K) and measure CFV and CAV concentrations. Controls were matched on the child's age at the time of sample collection. RESULTS: Women with a breast milk Na/K ratio suggestive of mastitis (>1.0) had an 11-fold greater odds of transmission (95% confidence interval [CI]: 1.2 to 98.1), compared to women with a Na/K

Breastfeeding, breast milk and viruses.

BACKGROUND: There is seemingly consistent and compelling evidence that there is no association between breastfeeding and breast cancer. An assumption follows that milk borne viruses cannot be associated with human breast cancer. We challenge this evidence because past breastfeeding studies did not determine "exposure" of newborn infants to colostrum and breast milk. METHODS: We conducted a prospective review of 100 consecutive births of infants in the same centre to determine the proportion of newborn infants who were "exposed" to colostrum or breast milk, as distinct from being fully breast fed. We also report a review of the breastfeeding practices of mothers of over 87,000 newborn infants in the Australian State of New South Wales. This study was approved by the Human Research Ethics Committee of the University of New South Wales (Sydney, Australia). Approval 05063, 29 September 2005. RESULTS: Virtually all (97 of 100) newborn infants in this centre were "exposed" to colostrum or breast milk whether or not they were fully breast fed. Between 82.2% to 98.7% of 87,000 newborn infants were "exposed" to colostrum or breast milk. CONCLUSION: In some Western communities there is near universal exposure of new born infants to colostrum and breast milk. Accordingly it is possible for the transmission of human milk borne viruses. This is contrary to the widespread assumption that human milk borne viruses cannot be associated with breast cancer.

Factors influencing breast milk HIV RNA viral load among Zambian women.

In a longitudinal cohort study we investigated factors contributing to breast milk HIV RNA viral load among lactating women in Lusaka, Zambia. Detailed data from 135 HIV-infected women were collected by questionnaires concerning postpartum maternal and infant health and infant feeding practice. Maternal blood was collected during pregnancy and at 6 weeks postpartum. Milk samples collected from each breast at 10 days and 6 weeks postpartum plus a subset collected at other time points were analyzed for HIV RNA viral load. Increased milk viral load was associated in univariate analyses with maternal symptoms of poor health, raised plasma alpha(1)-acid glycoprotein (AGP) at week 6, raised milk sodium/potassium (Na/K) ratio, postpartum need for antibiotics, preterm delivery, and low birth weight infants. In a multiple regression 49% of variability in mean milk viral load was explained by milk Na/K ratio and need for antibiotics, with borderline contributions from plasma AGP and plasma viral load. Maternal blood hemoglobin or receipt of iron supplements and infant feeding variables such as changing the infant's diet by moving from exclusive to nonexclusive breastfeeding or adding solid foods were not associated with milk viral load. Thus maternal health was the main factor contributing to milk viral load. The lack of effect of feeding practices on milk viral load and the previously determined association of poor maternal health with reduced duration of exclusive breastfeeding in this cohort suggest the relation between exclusive breastfeeding and decreased HIV transmission may be secondary to poor maternal health.