Breast milk transmission of viral disease

[Variation in the level of the biocomponents immunoglobulin A and lactoferrin in human milk after Holder pasteurization]

BACKGROUND

breast milk is the ideal food for newborns and infants, but there are factors that can prevent the practice of breastfeeding. Human milk banks (BLH) are a strategy to increase breastfeeding coverage; the donated milk is subjected to Holder pasteurization to guarantee its innocuousness, undergoing large changes in temperature and a decrease in the concentrations of biocomponents such as Immunoglobulin A (IgA) and lactoferrin (LF). This article describes the results of recent studies on the impact of Holder pasteurization on IgA and LF in human milk.

MATERIAL AND METHODS

a search for research articles related to the topic of interest was carried out in various databases and in accordance with inclusion criteria that considered the type of study, date of publication and quality of the journal.

RESULTS

the impact of Holder pasteurization on IgA and LF concentrations is not clear, given that the literature reports a variety of protocols and different results; however, the percentage reductions of both biocomponents are significant and consistent in the studies reviewed, suggesting the importance of establishing a standard protocol for their quantification.

CONCLUSIONS

Holder pasteurization guarantees the microbiological quality of the milk distributed in HMB, but affects the amount of beneficial biocomponents for the final recipient. Government entities that regulate HMBs should evaluate the possibility of using other techniques that reduce the impact on biocomponents while preserving the microbiological quality of the product.

Detection of SARS-CoV-2 in Human Breast Milk

Certain viral pathogens can be shed into the human breast milk and cause infections in the infant upon breastfeeding. Thus, it is important to clarify whether viral RNA as well as infectious virus can be found in breast milk. The complexity of this body fluid poses several challenges for viral RNA isolation and detection of infectious virus. We here provide a protocol that allowed the identification of SARS-CoV-2 RNA in breast milk and the isolation of infectious virus after the virus has been artificially spiked into milk samples.

What is the Hidden Biological Mechanism Underlying the Possible SARS-CoV-2 Vertical Transmission? A Mini Review

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS- CoV-2) represents an emerging infection that is spreading around the world. Among susceptible patients, pregnant women are more likely to develop serious complications and negative obstetric outcomes. Vertical transmission constitutes a debating issue which has not been completely understood. This review aims at describing the currently available evidence on SARS-CoV2 vertical transmission. We carried out a computerized literature search in the Cochrane Library, PubMed, Scopus and Web of Science, selecting the most relevant studies on vertical transmission from the outbreak onset until February 2022. The analysis of the available literature identifies the presence of SARS-CoV2 genome in different biological specimens, confirming the hypothesis that a transplacental infection can occur. In spite of the high number of infected people around the world, mother-to-child infections have been infrequently reported but it can be observed under certain biologic conditions. A deep knowledge of the underlying mechanisms of SARS-CoV2 vertical transmission is of paramount importance for planning an adequate management for the affected mothers and newborns.

Promoting and Protecting Human Milk and Breastfeeding in a COVID-19 World

The global COVID-19 pandemic has put enormous stress on healthcare systems and hospital staffing. However, through all this, families will continue to become pregnant, give birth, and breastfeed. Unfortunately, care of the childbearing family has been de-prioritized during the pandemic. Additionally, many healthcare practices during the pandemic have not been positive for the childbearing family or breastfeeding. Despite recommendations from the World Health Organization to promote early, direct breastfeeding and skin to skin contact, these and other recommendations are not being followed in the clinical setting. For example, some mothers have been forced to go through labor and birth alone in some institutions whilst some hospitals have limited or no parental visitation to infants in the NICU. Furthermore, hospitals are discharging mothers and their newborns early, limiting the amount of time that families receive expert lactation care, education, and technical assistance. In addition, some hospitals have furloughed staff or transferred them to COVID-19 wards, further negatively impacting direct care for families and their newborns. We are concerned that these massive changes in the care of childbearing families will be permanently adopted. Instead, we must use the pandemic to underscore the importance of human milk and breastfeeding as lifesaving medical interventions. We challenge healthcare professionals to change the current prenatal and post-birth practice paradigms to protect lactation physiology and to ensure that all families in need receive equal access to evidence-based lactation education, care and technical assistance.

Confirming Vertical Fetal Infection With Coronavirus Disease 2019: Neonatal and Pathology Criteria for Early Onset and Transplacental Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 From Infected Pregnant Mothers

Increasing numbers of pregnant women with coronavirus disease 2019 are being reported around the world. The majority of neonates delivered to pregnant women infected with severe acute respiratory syndrome coronavirus 2 have been negative for the virus, but a small number have tested positive for infection. It is important to determine whether vertical transmission of coronavirus disease 2019 occurs and the mechanisms for its development. Based on a number of clinical and laboratory findings, it has been suggested that transplacental transmission may be occurring, but a method to confirm this is necessary. This communication analyzes and evaluates the covariables that have been discussed as potential indicators of vertical and, specifically, intrauterine transmission, including the timing of onset of neonatal illness, neonatal viral test positivity, neonatal antibody testing for immunoglobulin (Ig) G and IgM, and viral analysis of swabs of whole specimens of placental tissue. None of these methods can provide confirmatory evidence that infection developed prior to labor and delivery, or that transplacental transmission occurred. This commentary proposes that diagnosis of early-onset neonatal coronavirus disease 2019 infection should be limited to neonates with positive reverse transcription polymerase chain reaction testing for severe acute respiratory syndrome coronavirus 2 within the initial 72 hours of life. It also proposes that the occurrence of intrauterine transplacental severe acute respiratory syndrome coronavirus 2 among infected mother-infant dyads be based upon identification of severe acute respiratory syndrome coronavirus 2 in chorionic villus cells using immunohistochemistry or nucleic acid methods such as in situ hybridization. Evaluating placentas from neonates with coronavirus disease 2019 using these methods will be instrumental in determining the potential role and prevalence of transplacental transmission of the coronavirus.

Detection of Zika virus in mouse mammary gland and breast milk

Clinical reports of Zika Virus (ZIKV) RNA detection in breast milk have been described, but evidence conflicts as to whether this RNA represents infectious virus. We infected post-parturient AG129 murine dams deficient in type I and II interferon receptors with ZIKV. ZIKV RNA was detected in pup stomach milk clots (SMC) as early as 1 day post maternal infection (dpi) and persisted as late as 7 dpi. In mammary tissues, ZIKV replication was demonstrated by immunohistochemistry in multiple cell types including cells morphologically consistent with myoepithelial cells. No mastitis was seen histopathologically. In the SMC and tissues of the nursing pups, no infectious virus was detected via focus forming assay. However, serial passages of fresh milk supernatant yielded infectious virus, and immunohistochemistry showed ZIKV replication protein associated with degraded cells in SMC. These results suggest that breast milk may contain infectious ZIKV. However, breast milk transmission (BMT) does not occur in this mouse strain that is highly sensitive to ZIKV infection. These results suggest a low risk for breast milk transmission of ZIKV, and provide a platform for investigating ZIKV entry into milk and mechanisms which may prevent or permit BMT.

Improving Pasteurization to Preserve the Biological Components of Donated Human Milk

Donor human milk (DHM) in human milk banks (HMB) is routinely subjected to heat treatment to ensure microbiological security, most guidelines recommending a temperature of 62. 5°C for 30 min. However, this procedure negatively impacts on milk quality, due to the destruction of biological components. Different studies have called for a more respectful treatment of DHM to preserve its properties, and have explored the use of alternative technologies. There is also clear evidence that bacterial and viral contamination in human milk can be effectively destroyed by temperatures lower than that currently recommended (62.5°C). Thus, a simple option would be to optimize the conventional pasteurization technique so the treated milk is free of infectious elements yet retains a maximum amount of biological components. An advantage of this approach is that it would be unnecessary to replace the pasteurization equipment currently available in most HMB. On the basis of a literature review, we here analyze and discuss evidence that pasteurization of human milk at a temperature below 62.5°C results in an improved preservation of its properties without compromising safety regarding the transmission of infectious agents.

Shared and Distinct Features of Human Milk and Infant Stool Viromes

Infants acquire many of their microbes from their mothers during the birth process. The acquisition of these microbes is believed to be critical in the development of the infant immune system. Bacteria also are transmitted to the infant through breastfeeding, and help to form the microbiome of the infant gastrointestinal (GI) tract; it is unknown whether viruses in human milk serve to establish an infant GI virome. We examined the virome contents of milk and infant stool in a cohort of mother-infant pairs to discern whether milk viruses colonize the infant GI tract. We observed greater viral alpha diversity in milk than in infant stool, similar to the trend we found for bacterial communities from both sites. When comparing beta diversity, viral communities were mostly distinguishable between milk and infant stool, but each was quite distinct from adult stool, urine, and salivary viromes. There were significant differences in viral families in the infant stool (abundant bacteriophages from the family Siphoviridae) compared to milk (abundant bacteriophages from the family Myoviridae), which may reflect significant differences in the bacterial families identified from both sites. Despite the differences in viral taxonomy, we identified a significant number of shared viruses in the milk and stool from all mother-infant pairs. Because of the significant proportion of bacteriophages transmitted in these mother-infant pairs, we believe the transmission of milk phages to the infant GI tract may help to shape the infant GI microbiome.

Environmental Stability and Infectivity of Hepatitis C Virus (HCV) in Different Human Body Fluids

Background: Hepatitis C virus (HCV) is a hepatotropic, blood-borne virus, but in up to one-third of infections of the transmission route remained unidentified. Viral genome copies of HCV have been identified in several body fluids, however, non-parental transmission upon exposure to contaminated body fluids seems to be rare. Several body fluids, e.g., tears and saliva, are renowned for their antimicrobial and antiviral properties, nevertheless, HCV stability has never been systematically analyzed in those fluids. Methods: We used state of the art infectious HCV cell culture techniques to investigate the stability of HCV in different body fluids to estimate the potential risk of transmission via patient body fluid material. In addition, we mimicked a potential contamination of HCV in tear fluid and analyzed which impact commercially available contact lens solutions might have in such a scenario. Results: We could demonstrate that HCV remains infectious over several days in body fluids like tears, saliva, semen, and cerebrospinal fluid. Only hydrogen-peroxide contact lens solutions were able to efficiently inactivate HCV in a suspension test. Conclusion: These results indicate that HCV, once it is present in various body fluids of infected patients, remains infective and could potentially contribute to transmission upon direct contact.

Maternal antibodies in breast milk protect the child from enterovirus infections

OBJECTIVE

Enterovirus infections are frequent in infants and may cause severe complications. We set out to assess whether breastfeeding can protect against these infections and whether such an effect is related to maternal antibodies in breast milk or in the peripheral circulation of the infant.

METHODS

One hundred fifty infants who were prospectively followed up from birth were monitored for enterovirus infections. The duration of breastfeeding was recorded, and maternal breast milk and blood samples were regularly taken at 3-month intervals for the detection of enterovirus antibodies and RNA. Maternal serum was available from early pregnancy, delivery, and 3 months postpartum.

RESULTS

Enterovirus infections were frequent and were diagnosed in 43% of infants before the age of 1 year and in 15% of the mothers during pregnancy. Infants exclusively breastfed for >2 weeks had fewer enterovirus infections by the age of 1 year compared with those exclusively breastfed for < or =2 weeks (0.38 vs 0.59 infections per child). High maternal antibody levels in serum and in breast milk were associated with a reduced frequency of infections. This effect was seen only in those infants breastfed >2 weeks, indicating that breast milk antibodies mediate this effect. Enterovirus RNA was not found in any of the breast milk samples.

CONCLUSIONS

These results suggest that breastfeeding has a protective effect against enterovirus infections in infancy. This effect seems to be mediated primarily by maternal antibodies in breast milk.