Acquisition of human cytomegalovirus infection in infants via breast milk: natural immunization or cause for concern?

Rapid detection of human cytomegalovirus by multienzyme isothermal rapid amplification and lateral flow dipsticks

Introduction

Human cytomegalovirus (HCMV) is the most common viral infection seen in newborns. The major route of transmission for acquired human cytomegalovirus infection is breast milk from mothers who are HCMV seropositive to the infants. Thus, a rapid, economical, and simple method to perform HCMV test in breast milk is crucial and necessary for preventing acquired HCMV infection, especially in underdeveloped regions with limited laboratory resources.

Methods

In this study, an effective technique for the detection of HCMV was constructed by combining multienzyme isothermal rapid amplification (MIRA) and lateral flow chromatography strip (LFD). Primers for the conserved HCMV sequence UL83 were utilized for MIRA-LFD testing.

Results

Our results showed that the entire MIRA reaction could be completed in 12 minutes at 37°C, and LFD outcomes could be observed visibly after 10 minutes. The detection sensitivity of this method reached 50 copy/μl. Samples of breast milk were examined to compare MIRA-LFD and conventional qPCR. The accuracy of MIRA-LFD was 100%.

Discussion

The straightforward, rapid, economic features of the test can provide the significant advantages for the prevention of breast milk-acquired cytomegalovirus infection, particularly in resource-limited locations with high seroprevalence of cytomegalovirus.

Viruses and Human Milk: Transmission or Protection?

Human milk (HM) is considered the best source of nutrition for infant growth and health. This nourishment is unique and changes constantly during lactation to adapt to the physiological needs of the developing infant. It is also recognized as a potential route of transmission of some viral pathogens although the presence of a virus in HM rarely leads to a disease in an infant. This intriguing paradox can be explained by considering the intrinsic antiviral properties of HM. In this comprehensive and schematically presented review, we have described what viruses have been detected in HM so far and what their potential transmission risk through breastfeeding is. We have provided a description of all the antiviral compounds of HM, along with an analysis of their demonstrated and hypothesized mechanisms of action. Finally, we have also analyzed the impact of HM pasteurization and storage methods on the detection and transmission of viruses, and on the antiviral compounds of HM. We have highlighted that there is currently a deep knowledge on the potential transmission of viral pathogens through breastfeeding and on the antiviral properties of HM. The current evidence suggests that, in most cases, it is unnecessarily to deprive an infant of this high-quality nourishment and that the continuation of breastfeeding is in the best interest of the infant and the mother.

Congenital Cytomegalovirus Infection and Hearing Outcomes in Twins: A Systematic Review of Reported Cases

OBJECTIVE

Congenital cytomegalovirus infection is the leading nonhereditary cause of pediatric sensorineural hearing loss. This systematic review evaluated infection concordance and comparative hearing abilities in twins/multiple births to model infection patterns.

DATABASES REVIEWED

PubMed, Embase, Web of Science, and Google Scholar.

METHODS

Studies that reported hearing outcomes of congenital cytomegalovirus infection in at least one multiple birth were eligible. Concordant infections (both twins) and discordant infections (single twin) were included. Multiple reviewers performed data extraction and quality assessment. Analyses involved relative risk of infection concordance by zygosity and chorionicity and odds of hearing loss by infection concordance. Hearing outcomes were compared between siblings.

RESULTS

Of 247 studies screened, 31 were included (74.2% high quality). The review captured 40 eligible multiple births. Among infected patients, 42.9% (95% confidence interval, 31.2-55.2%) demonstrated hearing loss. All uninfected twins had normal hearing. Most infections were concordant, and infected patients experienced 4.11 (1.18-14.36) times greater odds of hearing loss if their twin was also infected ( p = .02). Yet siblings' hearing outcomes diverged in over 40% of concordant cases. If either twin is infected, infection risk in the second twin is 3.25 (1.83-5.79) times greater in monozygotic than dizygotic twins and 2.50 (1.61-3.88) times greater in monochorionic than dichorionic twins (both p < .001). We describe a case from our practice.

CONCLUSION

Congenital cytomegalovirus infection patterns and hearing outcomes can vary widely even within a shared fetal and postnatal environment. Suspected infection in a twin indicates that both should receive testing and continued monitoring for late-onset sequelae.

Transmission of cytomegalovirus via breast milk in low birth weight and premature infants: a systematic review and meta-analysis

Background

This study aimed to investigate the transmission of cytomegalovirus (CMV) via breast milk in low birth weight (LBW) and premature infants and its effects.

Methods

PubMed, Medline, Cochrane Library, and Embase were searched for studies (without language and time restriction) published before March 27, 2020, that examined the effect of CMV transmitted by breast milk on LBW and premature infants. The rates of breast milk-acquired CMV infection, CMV-related symptoms, and CMV-related sepsis-like syndrome (CMV-SLS) in LBW and premature infants were pooled from each study.

Results

Eighteen studies with 1920 LBW and premature infants were included. The pooled CMV infection rate from breast milk for infants fed untreated breast milk was significantly higher than those fed frozen breast milk [19.3, 95% confidence interval (CI) = 11.8–29.9% vs. 13.5, 95% CI = 8.0–22.0%, P < 0.01). Similarly, the pooled CMV infection rate for infants fed untreated breast milk was significantly higher than those with mixed feeding (P < 0.0001). The mixed feeding group had a significantly lower rate of CMV-related symptoms than the other groups (2.4%, P < 0.01).

Conclusions

These findings suggested a higher CMV infection rate in LBW or premature infants fed untreated breast milk than other feeding groups. Studies on the long-term outcomes of CMV infection transmitted from breast milk are needed to address the optimal feeding practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02984-7.

Infantile nephrotic syndrome secondary to cytomegalovirus infection in a 7-month-old girl: resolution with ganciclovir

Infantile nephrotic syndrome is a rare disorder which is frequently caused by genetic defects. A 7-month-old girl presented with fever, loose stools and anasarca and was diagnosed with nephrotic syndrome. Work-up for a genetic cause was negative. Cytomegalovirus polymerase chain reaction (CMV PCR) was positive and the infant was treated with ganciclovir for 6 weeks, followed by valganciclovir for 10 weeks. All symptoms resolved within 2 weeks of commencing treatment and she attained complete remission within 4 weeks. CMV PCR was negative within 4 weeks of antiviral therapy. At 18 months follow-up she remained well. Appropriate treatment of infantile nephrotic syndrome secondary to CMV should result in recovery.

Impact of breast milk-acquired cytomegalovirus infection in premature infants: Pathogenesis, prevention, and clinical consequences?

Maternal-fetal transmission of cytomegalovirus (CMV) represents the most common infectious cause of long-term neurodevelopmental disability in children. Congenital CMV (cCMV) infection is associated with microcephaly, seizure disorders, cognitive disability, developmental delay, and sensorineural hearing loss (SNHL). Of these disabilities, SNHL is the most common, affecting approximately 10% of infants with cCMV. Although the sequelae of cCMV are well recognized, it is much less clear what long-term morbidities may occur in neonates that acquire post-natal CMV infection. Post-natal CMV (pCMV) infection is most commonly transmitted by breast-feeding, and in full-term infants is of little consequence. However, in preterm, very-low birthweight (VLBW) infants (<1500 g), pCMV can result in a severe sepsis-like syndrome, with wide-ranging end-organ disease manifestations. Although such short-term complications are well recognized among clinicians caring for premature infants, the long-term risks with respect to adverse neurodevelopmental outcomes remain controversial. In this review, we provide an overview of the clinical manifestations of breast milk-acquired pCMV infection. In particular, we summarize studies that have examined-sometimes with conflicting conclusions-the risks of long-term adverse neurodevelopmental outcome in VLBW infants that acquire pCMV from breast milk. We highlight proposed preventive strategies and antiviral interventions, and offer recommendations for high-priority areas for future basic science and clinical research.

Immune Correlates of Protection Against Human Cytomegalovirus Acquisition, Replication, and Disease

Human cytomegalovirus (HCMV) is the most common infectious cause of infant birth defects and an etiology of significant morbidity and mortality in solid organ and hematopoietic stem cell transplant recipients. There is tremendous interest in developing a vaccine or immunotherapeutic to reduce the burden of HCMV-associated disease, yet after nearly a half-century of research and development in this field we remain without such an intervention. Defining immune correlates of protection is a process that enables targeted vaccine/immunotherapeutic discovery and informed evaluation of clinical performance. Outcomes in the HCMV field have previously been measured against a variety of clinical end points, including virus acquisition, systemic replication, and progression to disease. Herein we review immune correlates of protection against each of these end points in turn, showing that control of HCMV likely depends on a combination of innate immune factors, antibodies, and T-cell responses. Furthermore, protective immune responses are heterogeneous, with no single immune parameter predicting protection against all clinical outcomes and stages of HCMV infection. A detailed understanding of protective immune responses for a given clinical end point will inform immunogen selection and guide preclinical and clinical evaluation of vaccines or immunotherapeutics to prevent HCMV-mediated congenital and transplant disease.

Detection of Cytomegalovirus in Intestinal Tissue of Infants with Necrotizing Enterocolitis or Spontaneous Intestinal Perforation

OBJECTIVE

To determine the frequency of detection of cytomegalovirus (CMV) in surgical or autopsy intestinal tissue from infants with necrotizing enterocolitis (NEC) or spontaneous intestinal perforation (SIP) of the small bowel.

STUDY DESIGN

This was a retrospective cohort study of infants in the neonatal intensive care unit at Nationwide Children's Hospital, Columbus, Ohio, with NEC (Bell stage ≥2B) or SIP from 2000 to 2016. Paraffin-embedded surgical or autopsy intestinal tissues were examined for CMV by polymerase chain reaction (PCR) and immunohistochemistry (IHC), and clinical characteristics of CMV-positive vs CMV-negative cases were compared.

RESULTS

CMV was detected by PCR or IHC in 7 (4%) of 178 infants with surgical or autopsy- confirmed NEC (n = 6) or SIP (n = 1). Among 143 NEC cases (123 surgical, 20 autopsy), CMV was detected in 6 (4%): 4 (2 surgical, 2 autopsy) by both PCR and IHC, and 2 (surgical) by PCR only. Among 35 SIP cases (32 surgical, 3 autopsy), 1 (3%) surgical case was positive, by PCR only. CMV-associated NEC cases had lower median gestational age (24 vs 28 weeks; P = .02), birth weight (649 vs 1121 g; P = .04), and platelet count (16 000/mm³ vs 50 000/mm³; P = .018) compared with CMV-negative cases, respectively. No association was found with receipt of maternal milk, age at NEC diagnosis, male sex, cholestasis, or mortality.

CONCLUSIONS

CMV was detected in intestinal tissue from 4% of NEC or SIP cases (NEC, 4%; SIP, 3%). Lower gestational age, lower birth weight, and thrombocytopenia were significantly associated with detection of CMV in NEC or SIP cases.

Cytomegalovirus: Shape-Shifting the Immune System

Systems-based based approaches have begun to shed light on extrinsic factors that contribute to immune system variation. Among these, CMV (HHV-5, a β-herpesvirus) imposes a surprisingly profound impact. Most of the world's population is CMV⁺, and the virus goes through three distinct infection phases en route to establishing lifelong détente with its host. Immune control of CMV in each phase recruits unique arms of host defense, and in turn the virus employs multiple immune-modulatory strategies that help facilitate the establishment of lifelong persistence. In this review, we explain how CMV shapes immunity and discuss the impact it may have on overall health.

Human Breast Milk-acquired Cytomegalovirus Infection: Certainties, Doubts and Perspectives

Breast Milk (BM) is the best source of nutrition for newborns, especially if premature. In fact, its beneficial impact on short- and the long-term neonatal outcome has was deeply described. Unfortunately, BM could not be always so safe, especially due to the possible presence of maternal viruses that can be shed and transferred to the breastfed neonate. Among these, Cytomegalovirus (CMV) can potentially lead to a serious and acute illness, mostly in case of low gestational age. Some studies also report the association of CMV-acquired infection to an increased risk of structural and functional brain modifications and neurological impairment. Due to these reasons, a strategy to remove CMV from BM with a minimal or absent impact on its beneficial components would be desirable. Up to now, pasteurization, freezing, ultraviolet- C or microwave irradiation are the available techniques; they show different levels of efficacy and variable effects on BM composition, even if many studies are still needed to fully clarify these implications. In this review, we provide an update of the current evidence about these topics. We focus on the factors promoting CMV shedding through BM; moreover, the possible occurrence of a severe disease in preterm neonates is also described. Finally, we investigate the potential effects showed on BM properties by the strategies that prevent or reduce viral transmission, therefore influencing newborns' health, and the new techniques which could show a relevant role in the next future, such as metabolomics.

Anti-Cytomegalovirus Activity in Human Milk and Colostrum From Mothers of Preterm Infants

OBJECTIVES

This study aimed to investigate the anti-human cytomegalovirus (CMV) activity of milk from seropositive and seronegative mothers of preterm infants and to analyze its changes throughout the different stages of lactation and after Holder pasteurization, a procedure adopted by donor human milk banks.

METHODS

Eighteen mothers of preterm infants were enrolled in the study. Colostrum, transitional milk, and mature milk samples were collected and tested for anti-CMV activity. Depletion of immunoglobulins A from milk samples was carried out by jacalin resin. Pools of milk samples were pasteurized according to Holder technique.

RESULTS

All samples were endowed with anti-CMV activity, although to a different extent. In CMV IgG-positive mothers, colostra were significantly more active than the transitional milk and mature milk samples. Moreover, they were more potent than colostra from seronegative mothers. Immunoglobulins A depletion in colostra from IgG-positive mothers resulted in a partial loss of anti-CMV activity. Holder pasteurization significantly reduced the antiviral activity.

CONCLUSIONS

Human milk is endowed with anti-CMV activity and its potency may vary depending on the stage of lactation and the serological status of the mother. This biological property could partially neutralize CMV particles excreted in the milk of CMV IgG-positive mothers thus reducing the risk of transmitting infectious viruses to the infant.

Cytomegalovirus, Epstein-Barr virus and varicella zoster virus infection in the first two years of life: a cohort study in Bradford, UK

Background

Cytomegalovirus (CMV), Epstein Barr virus (EBV) and varicella-zoster virus (VZV) are common herpesviruses frequently acquired in childhood, which establish persistent, latent infection and are likely to impact the developing immune system. Little is known about the epidemiology of CMV and EBV infections in contemporary UK paediatric populations, particularly whether age at infection differs by ethnic group.

Methods

Children enrolled in the Born in Bradford Allergy and Infection Study had a blood sample taken and a questionnaire completed at 12 and 24 months of age. Ordered logistic regression quantified associations between ethnicity and other risk factors and age at CMV/EBV/VZV infection (<12 months, 12–24 months, uninfected at 24 months).

Results

Pakistani children (n = 472) were more likely to be infected with CMV and EBV at a younger age than White British children (n = 391) (CMV: adjusted odds ratio (OR) 2.53, 95% confidence interval (CI) 1.47–4.33; EBV: adjusted OR 2.16, 95% CI 1.43–3.26). Conversely, Pakistani children had lower odds of being VZV infected in the second year than White British children (adjusted OR 0.57, 95% CI 0.33–0.97). There was a strong association between increasing birth order and later CMV infection in Pakistani children.

Conclusions

We report large differences in CMV and EBV incidence in the first 2 years between Pakistani and White British children born in Bradford, which cannot be explained by differences in risk factors for infection. Our data will inform the optimum schedule for future CMV and EBV vaccination programmes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2319-7) contains supplementary material, which is available to authorized users.

Murine Cytomegalovirus Exploits Olfaction To Enter New Hosts

Viruses transmit via the environmental and social interactions of their hosts. Herpesviruses have colonized mammals since their earliest origins, suggesting that they exploit ancient, common pathways. Cytomegaloviruses (CMVs) are assumed to enter new hosts orally, but no site has been identified. We show by live imaging that murine CMV (MCMV) infects nasally rather than orally, both after experimental virus uptake and during natural transmission. Replication-deficient virions revealed the primary target as olfactory neurons. Local, nasal replication by wild-type MCMV was not extensive, but there was rapid systemic spread, associated with macrophage infection. A long-term, transmissible infection was then maintained in the salivary glands. The viral m131/m129 chemokine homolog, which influences tropism, promoted salivary gland colonization after nasal entry but was not required for entry per se. The capacity of MCMV to transmit via olfaction, together with previous demonstrations of experimental olfactory infection by murid herpesvirus 4 (MuHV-4) and herpes simplex virus 1 (HSV-1), suggest that this is a common, conserved route of mammalian herpesvirus entry.

Cytomegaloviruses (CMVs) infect most mammals. Human CMV (HCMV) harms people with poor immune function and can damage the unborn fetus. It infects approximately 1% of live births. We lack a good vaccine. One problem is that how CMVs first enter new hosts remains unclear. Oral entry is often assumed, but the evidence is indirect, and no infection site is known. The difficulty of analyzing HCMV makes related animal viruses an important source of insights. Murine CMV (MCMV) infected not orally but nasally. Specifically, it targeted olfactory neurons. Viral transmission was also a nasal infection. Like HCMV, MCMV infected cells by binding to heparan, and olfactory surfaces display heparan to incoming viruses, whereas most other mucosal surfaces do not. These data establish a new understanding of CMV infections and a basis for infection control.

Pharmacokinetic considerations in the use of antivirals in neonates

INTRODUCTION

Neonatal patients, because of the inability of their immune system to properly respond to microbial challenge, are highly susceptible to viral infections. Immunoglobulins, monoclonal antibody and antiviral drugs are used for prophylaxis and treatment of viral diseases in neonates. Neonates and, especially, preterm infants differ in drug absorption, distribution, metabolism and excretion from adults and older children.

AREAS COVERED

This review will evaluate deficiencies of neonatal immune responses to microbial challenge that predispose newborns to viral infections, clinical manifestations and the treatment of viral diseases in neonates. We focus on published studies describing antiviral drug pharmacokinetics in neonates and make recommendations on the dosing of these drugs, allowing achievement of maximal clinical benefits in neonates.

EXPERT OPINION

While some efforts were undertaken to study pharmacokinetics and pharmacodynamics of antiviral drugs, much more needs to be done. Current data indicate that the pharmacokinetics of antiviral drugs may vary significantly depending on gestational age, maturation processes of drug-metabolizing enzymes and renal clearance. Specifics of pharmacokinetics of antiviral drugs need to be taken into consideration when they are prescribed to neonates and infants.

Congenital cytomegalovirus infection: Clinical presentation, epidemiology, diagnosis and prevention

Cytomegalovirus is the most common congenital infection causing serious disease in infants. It is the leading infectious cause of sensorineural hearing loss and neurodevelopmental disability in developed countries. Despite the clinical importance of congenital cytomegalovirus, surveys show there is limited awareness and knowledge in the medical and general community about congenital cytomegalovirus infection. This article reviews the clinical features, global epidemiology, transmission and risk factors for cytomegalovirus infections. It also highlights several major advances made in recent years in the diagnosis and prevention of cytomegalovirus infection during pregnancy. Although research is ongoing, no therapy is currently proven to prevent or treat maternal, fetal or neonatal cytomegalovirus infection. Education of women regarding hygiene measures can help prevent cytomegalovirus infection and are currently the best strategy to prevent congenital cytomegalovirus disease.

Herpesvirus delivery to the murine respiratory tract

Herpesvirus transmission is sporadic, and infection may be asymptomatic or present only with secondary lesions after dissemination. Consequently host entry remains ill-understood. Experimental infections can be informative, but depend on inoculations that are inherently artificial and so need validation. Mice are a widely used experimental host. Alert mice inhale readily small (5 μl) liquid volumes, and Indian ink, luciferase or radiolabel delivered thus distributed to the nasopharynx and oropharynx. Murid Herpesvirus-4 or Herpes simplex virus type 1 delivered thus infected only the nose, arguing that host entry is nasal rather than oral. Marker or virus delivery to the lung depended on general anesthesia and a large inoculum volume (30 μl), and so needs further validation of physiological relevance. While lungs could be infected at lower doses than the upper respiratory tract, tracking experiments showed that nasal inocula pass mostly into the oropharynx, even when restricted to 1 μl. Thus, the relative inefficiency of experimental upper respiratory tract infection was attributable to limited liquid retention in this site. Nonetheless low volume intranasal delivery to alert mice provides a convenient way to model experimentally an apparently natural mode of herpesvirus host entry.

Asymptomatic DNAemia heralds CMV-associated NEC: case report, review, and rationale for preemption

Human cytomegalovirus (CMV) infection may be acquired in very low birth weight and extremely low birth weight (ELBW) infants from breast milk. The clinical relevance of such infections is uncertain. There is no consensus on whether screening breast milk for CMV, freezing/pasteurizing milk before feeding, or performing virological monitoring on at-risk infants is warranted. We describe an ELBW infant who acquired CMV postnatally from breast milk and developed CMV sepsis syndrome and clinical evidence of necrotizing enterocolitis (NEC) at ≈ 5 weeks of age. The availability of serial dried blood spots from day of life (DOL) 4 to 21, coincidentally obtained for a metabolic study, provided the novel opportunity to retrospectively test for and quantify the magnitude of CMV DNAemia. DNAemia was present for several weeks before the onset of severe CMV disease, first being noted on DOL 18 and increasing in magnitude daily to 4.8 log10 genomes/mL on DOL 21, approximately 8 days before the onset of abdominal distension and 15 days before the onset of CMV sepsis syndrome and NEC. After surgical resection, supportive care, and ganciclovir therapy, the infant recovered. This case underscores the importance of including CMV infection in the differential diagnosis of sepsis and NEC in premature infants. This case also suggests the value of prospective virological monitoring in at-risk low birth weight and ELBW infants. Future studies should examine the potential utility of preemptive monitoring for, and possibly treatment of, CMV DNAemia in premature infants, which may herald the onset of serious disease.

Clinically targeted screening for congenital CMV - potential for integration into the National Hearing Screening Programme

Screening for a condition should only be undertaken if certain strict criteria are met. Congenital CMV (cCMV) is a leading cause of sensorineuronal hearing loss (SNHL) and meets many of these criteria, but is not currently screened for in the UK. Ganciclovir reduces CMV-induced progressive SNHL if treatment is begun in the first month of life. The Newborn Hearing Screening Programme (NHSP) has been shown to identify SNHL at the earliest possible age. The potential of integrating screening for cCMV into the NHSP is discussed to consolidate the link between screening, early diagnosis and management.

CONCLUSION

The early diagnosis and treatment of cCMV may prevent a small proportion of late SNHL. In the absence of any screening programme, we provide evidence that clinically targeted screening through the NHSP is a potential option in the UK, enhancing the diagnostic pathway and enabling appropriate early treatment to reduce long-term morbidity.

Susceptibility to cytomegalovirus, parvovirus B19 and age-dependent differences in levels of rubella antibodies among pregnant women

Infections caused by cytomegalovirus (CMV), parvovirus B19 (B19), and rubella can lead to serious complications in pregnant women. The aim of this study was to determine the susceptibility to CMV, B19, and rubella antibodies in pregnant women in Norway. Consecutive sera samples were collected from pregnant women in two different regions in Norway. Sera were collected from age groups; ≤19, 20-24, 25-29, 30-34, 35-39, and ≥40 years old. Of the 2,000 pregnant women tested, anti-CMV IgG was positive in 62.8% anti-parvovirus B19 IgG in 59.7% and anti-rubella IgG in 94.4%. CMV IgG susceptibility has decreased in pregnant women less than 30 years of age, from 60% in a study conducted in 1973-1974 to 37.2% in present study. There was a significant difference in CMV IgG seropositivity rate between the two regions (58.6% and 67.1%). Serum levels of rubella IgG was lowest in age group 25-29 years with a positivity rate of 91.0%. Women born before vaccination with two doses of MMR started, had both a higher positivity rate and significantly higher levels of rubella antibody titre, 96.1% and 82.2 IU/ml compared to those born after 92.9% and 41.7 IU/ml. Significantly lower anti-rubella IgG titre found in the youngest age groups highlights the need for continued antenatal screening. A considerable increase in anti-CMV-IgG seropositivity rate was observed and might be associated with higher rate of breastfeeding and a higher percentage attending day-care centres.

Cytomegalovirus in the neonate: immune correlates of infection and protection

Fetal and neonatal infections caused by human cytomegalovirus (CMV) are important causes of morbidity and occasional mortality. Development of a vaccine against congenital CMV infection is a major public health priority. Vaccine design is currently focused on strategies that aim to elicit neutralizing antibody and T-cell responses, toward the goal of preventing primary or recurrent infection in women of child-bearing age. However, there has been relatively little attention given to understanding the mechanisms of immune protection against acquisition of CMV infection in the fetus and newborn and how this information might be exploited for vaccine design. There has similarly been an insufficient study of what deficits in the immune response to CMV, both for mother and fetus, may increase susceptibility to congenital infection and disease. Protection of the fetus against vertical transmission can likely be achieved by protection of the placenta, which has its own unique immunological milieu, further complicating the analysis of the correlates of protective immunity. In this review, the current state of knowledge about immune effectors of protection against CMV in the maternal, placental, and fetal compartments is reviewed. A better understanding of immune responses that prevent and/or predispose to infection will help in the development of novel vaccine strategies.

Congenital cytomegalovirus infection: new prospects for prevention and therapy

Cytomegalovirus is the commonest congenital viral infection in the developed world, with an overall prevalence of approximately 0.6%. Approximately 10% of congenitally infected infants have signs and symptoms of disease at birth, and these symptomatic infants have a substantial risk of subsequent neurologic sequelae. These include sensorineural hearing loss, mental retardation, microcephaly, development delay, seizure disorders, and cerebral palsy. Antiviral therapy for children with symptomatic congenital cytomegalovirus infection is effective at reducing the risk of long-term disabilities and should be offered to families with affected newborns. An effective preconceptual vaccine against CMV could protect against long-term neurologic sequelae and other disabilities.

Burden of disease associated with human cytomegalovirus and prospects for elimination by universal immunisation

Cytomegalovirus is the most frequent cause of intrauterine infection and the commonest infectious agent to affect allograft recipients, yet the virus is acknowledged rarely as an occupational hazard for women of childbearing age or as a nosocomial infection. The potential role of cytomegalovirus in hastening the death of patients with AIDS, elderly people, individuals admitted to intensive-care units, and the general population is not emphasised. Development of vaccines against this important human pathogen has been delayed by reluctance to initiate proof-of-concept studies, but after recent trials, protection is a distinct possibility. Cytomegalovirus deserves to be eliminated from selected populations by means of universal immunisation as soon as suitable vaccines become licensed. This action should control disease in neonates and transplant recipients and could provide substantial additional benefits if other disease associations prove to be causal.

Transmission of cytomegalovirus via breast milk in extremely premature infants

OBJECTIVE

We prospectively evaluated the rate of postnatal cytomegalovirus (CMV) transmission through breast milk in extremely premature infants to address the impact of CMV infection on preterm infants during lactation.

STUDY DESIGN

A total of 25 mothers and 27 infants (two sets of twins) with birth weights <1000 g and/or gestational ages <28 weeks were enrolled in the study. They were mostly fed frozen-thawed breast milk. Breast milk, serum and urine samples were collected every 2 weeks and screened for CMV infection using the real-time polymerase chain reaction.

RESULT

All of the 21 CMV-seropositive mothers had detectable CMV DNA in their breast milk, with a peak at 4 to 6 weeks postpartum. CMV infection was confirmed in only one infant (4.3%) who displayed almost no clinical symptoms.

CONCLUSION

At our institutes, we mainly use frozen-thawed breast milk. We found low CMV transmission rates even in extremely premature infants, and the CMV-positive infant did not develop serious symptoms.

Transmission of cytomegalovirus via breast milk to the prematurely born infant: a systematic review

To analyse current data on transmission of human cytomegalovirus (HCMV) via breast milk with subsequent symptomatic HCMV infection of the preterm infant and to report on long-term follow-up, a systematic literature review was performed using EMBASE, MEDLINE and CINAHL (January 1966 to December 2008) Studies were included for analysis if congenital HCMV infection was excluded and transmission via breast milk was either confirmed or strongly suspected. Twenty-six studies were included for analysis. Maternal HCMV-IgG-positivity was reported to be in the range 51.6-100% (median 81.6%), HCMV-IgG detection in breast milk in the range 67-97.2% (median 80%) and HCMV-positivity of the infants in the range 5.7-58.6%. Symptomatic HCMV disease occurred in 0-34.5% (median 3.7%) and severe sepsis-like syndrome in 0-13.8% (median 0.7%). Data on long-term outcome of preterm infants with symptomatic HCMV infection revealed a low risk for mild neurological and cognitive sequelae, without hearing impairment. Recommendations for high-risk preterm infants diverged markedly. The current data report low rates of symptomatic disease after transmission of HCMV via breast milk to the preterm infant without evidence of certain long-term sequelae. The results of our review do not support a general approach, either by avoidance or pasteurization of breast milk, in high-risk preterm infants.

Public health and laboratory considerations regarding newborn screening for congenital cytomegalovirus

Congenital cytomegalovirus (CMV) infection is the most common infection in newborns worldwide and causes hearing loss and other neurological disability in 15-20% of infected infants. Only about half of the hearing loss resulting from congenital CMV infection is currently detected by universal newborn hearing screening because of late-onset hearing loss. Thus, much of the hearing loss and the majority of other CMV-associated disabilities remain undetected for years after birth and are never connected to CMV infection. Congenital CMV may be appropriate to include in national newborn screening (NBS) programs because it is more common than other disorders tested for by NBS programs and is a major cause of disability. Significant obstacles to the implementation of screening for congenital CMV include the lack of a standardized, high-throughput screening test and a protocol for follow-up of CMV-infected children. Nonetheless, screening newborns for congenital CMV infection merits further consideration.

Prevention of maternal cytomegalovirus infection: current status and future prospects

Human cytomegalovirus (CMV) infection is the most common cause of perinatal viral infection in the developed world, resulting in approximately 40,000 congenitally infected infants in the United States each year. Congenital CMV infection can produce varying degrees of neurodevelopmental disabilities. The significant impact of congenital CMV has led the Institute of Medicine to rank development of a CMV vaccine as a top priority. Vaccine development has been ongoing; however no licensed CMV vaccine is currently available. Treatment of pregnant women with CMV hyperimmune globulin has shown promising results, but has not been studied in randomized controlled trials. Education on methods to prevent CMV transmission, particularly among young women of child-bearing age, should continue until a CMV vaccine becomes available. The epidemiology, clinical manifestations, prevention strategies, and treatment of CMV infections are reviewed.

High cytomegalovirus load and prolonged virus excretion in breast milk increase risk for viral acquisition by very low birth weight infants

BACKGROUND

Breast milk is the main source of postnatal human cytomegalovirus (HCMV) infection. The aim of this study was to assess the relationship between HCMV load in breast milk and viral transmission to very low birth weight (VLBW) infants.

METHODS

Breast-fed VLBW infants who were born to HCMV-seropositive mothers and who were managed in a neonatal intensive care unit were enrolled in the study. Blood from mothers and infants was tested for HCMV antibodies after birth. Breast milk was collected for viral culture and HCMV load measurement. Urine from the babies was obtained for HCMV-DNA detection. Symptoms of HCMV infection were recorded and evaluated by neonatologists.

RESULTS

Of the 23 evaluated mothers during a 1-year period, 19 were HCMV seropositive; 17 of the women had detectable HCMV-DNA in their breast milk whey. Of the 23 infants born to the 19 seropositive mothers, 8 infants of 8 mothers had HCMV-DNA detected in the urine, indicating that they were infected, even though the breast milk was always frozen prior to feeding. Three infected infants had symptoms. At 4 weeks after delivery, the median viral load in breast milk from mothers of the 8 infected infants was significantly higher than that from mothers of the 15 noninfected infants (P = 0.04). HCMV was detectable in breast milk for a significantly longer period in mothers of infected infants (7.5 vs. 2.6 weeks P = 0.03).

CONCLUSIONS

High HCMV load and prolonged virus excretion in breast milk are maternal risk factors for viral transmission to VLBW infants.

Effects of different CMV-heat-inactivation-methods on growth factors in human breast milk

Preterm infants can inoculate virulent cytomegalovirus (CMV) through their mothers' raw breast milk. Complete virus inactivation is achieved only by heat treatment, but the effect on growth factors has never been assessed systematically. Insulin-like-growth-factor-1-, IGF-2-, insulin-like-growth-factor-binding-protein-2-, and IGFBP-3-concentrations were measured, before and after heating, in 51 breast-milk-samples from 28 mothers, and epidermal-growth-factor-concentrations in a subgroup of 35 samples from 22 mothers. Two heating methods were applied: Short-term (5 s) pasteurisation at 62, 65, and 72 degrees C, and long-term Holder-Pasteurisation (30 min) at 63 degrees C. IGF-1, IGF-2, IGFBP-2, and IGFBP-3 were measured by RIA, and EGF by ELISA. Heating for 30 min decreased significantly IGF-1 by 39.4%, IGF-2 by 9.9%, IGFBP-2 by 19.1%, and IGFBP-3 by 7.0%. In contrast, IGF-1, IGF-2, IGFBP-2, and IGFBP-3 were not altered significantly when using a short heating duration of 5 s, irrespective of the level of temperature, except for IGF-2 at 62 degrees C for 5 s (p = 0.041) and IGFBP-2 at 72 degrees C for 5 s (p = 0.025). Neither long- nor short-time heating methods changed the concentration of EGF. Only short heating methods (5 s, 62-72 degrees C) can preserve, almost completely, the concentrations of IGFs in human milk, whereas Holder-Pasteurization does not.

Immunological outcomes of exercise in older adults

Aging is associated with a dysregulation of the immune system known as immunosenescence. Immunosenescence involves cellular and molecular alterations that impact both innate and adaptive immunity, leading to increased incidences of infectious disease morbidity and mortality as well as heightened rates of other immune disorders such as autoimmunity, cancer, and inflammatory conditions. While current data suggests physical activity may be an effective and logistically easy strategy for counteracting immunosenescence, it is currently underutilized in clinical settings. Long-term, moderate physical activity interventions in geriatric populations appear to be associated with several benefits including reduction in infectious disease risk, increased rates of vaccine efficacy, and improvements in both physical and psychosocial aspects of daily living. Exercise may also represent a viable therapy in patients for whom pharmacological treatment is unavailable, ineffective, or inappropriate. The effects of exercise impact multiple aspects of immune response including T cell phenotype and proliferation, antibody response to vaccination, and cytokine production. However, an underlying mechanism by which exercise affects numerous cell types and responses remains to be identified. Given this evidence, an increase in the use of physical activity programs by the healthcare community may result in improved health of geriatric populations.

Diagnosis of congenital CMV infection via dried blood spots

Cytomegalovirus (CMV) infection is the most frequent congenital infection in humans and can cause permanent damage--particularly neurological--in about 20% of those infected, with or without symptoms at birth. Laboratory diagnosis is essential on account of the relatively non-specific clinical manifestations in symptomatic newborns but also because of the high frequency of asymptomatic cases that are nevertheless at risk of lesions later in life. However, these tests need samples taken within 3 weeks of birth to distinguish congenital infection from the more common, but clinically benign, perinatal infection. Tests for viral DNA have proved a valid means of diagnosing congenital CMV infection in neonatal blood dried on paper (DBS) widely used in screening for metabolic and genetic diseases, as an alternative to the conventional urine culture method. The DBS test is simpler, faster and less costly than viral isolation; in addition the samples can be safely stored for long periods, so diagnosis can be made even after several years. The sensitivity and specificity of the DBS test, compared to the reference method, have been reported to range between 71 and 100% and 99 and 100%, respectively, depending on the different studies and diagnostic criteria applied. The most interesting applications reported so far involve retrospective determination of the impact of congenital CMV in sensorineural deafness, abnormalities of cortical development, neonatal cholestasis and surveys of the prevalence of this infection in various populations. The test might be useful in the future for neonatal screening with a view to treating neonates and so avoiding the damage this disease can cause.