Sequelae of maternally derived cytomegalovirus infections in premature infants

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.

Long-term Outcomes after Postnatal Cytomegalovirus Infection in Low Birthweight Preterm Infants: A Systematic Review

BACKGROUND

Cytomegalovirus (CMV) is the most common viral infection seen in newborns. Although postnatally acquired CMV (pCMV) infection rarely results in serious manifestations in term infants, preterm infants can develop severe clinical illness. However, the long-term implications of pCMV infection of preterm infants are unknown. Few robust studies on long-term outcomes of pCMV infection have been performed, and those reported often present conflicting results. Our objective was to assess the long-term outcomes for low birthweight (LBW) preterm infants after pCMV infection.

METHODS

A systematic review of English and non-English articles using MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, CINAHL, and Web of Science was conducted. Search strategies included a mix of keywords and database-specific subject headings for CMV and LBW infants. Editorials, comments, reviews and animal-only studies were excluded. Case reports, observational, experimental and randomized controlled trials that examined pCMV in preterm or VLBW infants and long-term (>1 month) impact of pCMV were included.

RESULTS

pCMV infection in preterm infants is associated with increased risk for pulmonary and neurologic complications and increases length of stay. There is less evidence to suggest that pCMV is associated with necrotizing enterocolitis, ophthalmologic, audiologic and anthropomorphic complications in preterm infants.

CONCLUSIONS

Preterm infants with pCMV, especially those with symptomatic infection, may have long-term pulmonary and neurodevelopmental morbidity compared with their pCMV negative counterparts. Our results highlight the importance of pCMV detection and prevention in preterm infants in the neonatal intensive care unit. Large prospective studies are needed to fully define outcomes and determine if treatment improves outcomes.

Symptomatic Postnatal Cytomegalovirus Testing among Very Low-Birth-Weight Infants: Indications and Outcomes

Objective The objective of this study was to describe the indications for postnatal cytomegalovirus (CMV) testing among very low-birth-weight (VLBW, birth weight [BW] < 1,500 g) infants, clinical characteristics of infected infants, and adverse outcomes associated with CMV infection. Study Design This is a single-center, retrospective study of 2,132 VLBW infants from 1999 to 2013. Results In this study, 145 (6.8%) infants out of 2,132 were evaluated for postnatal CMV infection and 27 (18.6%) infants out of 145 were infected. CMV-tested infants were of significantly lower gestational age and BW compared with untested VLBW infants (p < 0.001). Respiratory decompensation and thrombocytopenia were the findings most commonly associated with infection. CMV-infected infants had significantly more exposure to mechanical ventilation and longer duration of hospitalization. Adjusting for multiple predictors of respiratory morbidity, the incidence of bronchopulmonary dysplasia (BPD) was significantly elevated among infants diagnosed with postnatal CMV infection (odds ratio, 4.0 [95% confidence interval, 1.3-12.4); p, 0.02.) Conclusion Symptomatic postnatal CMV infection was diagnosed in 1.3% of VLBW infants, most commonly among infants with BW < 1,000 g with respiratory instability and thrombocytopenia. Similar to late-onset bacterial infection, symptomatic postnatal CMV infection may be an independent contributor to the development of BPD. This possibility should be addressed in a prospective study of extremely low BW infants.

Outcome of Preterm Infants With Postnatal Cytomegalovirus Infection via Breast Milk: A Two-Year Prospective Follow-Up Study

Approximately 15% of preterm infants may develop postnatal cytomegalovirus (CMV) infection from seropositive mothers via breast milk and are at risk for neurological sequelae in childhood. The aims of this study were to assess the effects and outcomes on growth, neurodevelopmental status, and hearing in very low birth weight (VLBW) premature infants with postnatal CMV infection via breast milk at the corrected age of 12 and 24 months.The prospective follow-up study population comprised all living preterm children (n = 55) with a birth weight ≤1500 g and gestational age of ≤35 weeks, who had been participated in our "postnatal CMV infection via breast milk" studies in 2000 and 2009, respectively. The cohort of children was assessed at 12 and 24 months. Clinical outcomes were documented during hospitalization and after discharge. Long-term outcomes included anthropometry, audiologic tests, gross motor quotient, Infant International Battery, and neurodevelopmental outcomes; all were assessed at postcorrected age in 12 and 24 months during follow-up visits.Of the 55 infants enrolled in the study (4 noninfected infants were excluded because their parents did not join this follow-up program later), 14 infants postnatally acquired CMV infection through breast-feeding (infected group) and were compared with 41 infants without CMV infection (control group). No significant differences were observed between the groups with regard to baseline characteristics, clinical outcomes, anthropometry, or psychomotor and mental development on the Bayley scale of infant development. None of the infants had CMV-related death or permanent sensorineural hearing loss.Transmission of CMV from seropositive mother via breast milk to preterm infants does not appear at this time to have major adverse effects on clinical outcomes, growth, neurodevelopmental status, and hearing function at 12 and 24 months corrected age.

Cytomegalovirus

PURPOSE OF REVIEW

To consider new treatment options for cytomegalovirus (CMV) infection, review recent trials, and anticipate their use in clinical practice, focussing on bone marrow transplantation, congenital infection, and intervention during pregnancy.

RECENT FINDINGS

Three double-blind randomized placebo-controlled phase 2 proof-of-concept studies have each identified a novel antiviral drug with activity against CMV infection in bone marrow transplant patients. One of these (brincidofovir) inhibits the DNA polymerase that is the target of the currently licensed drug ganciclovir. Another new drug (maribavir) inhibits a protein kinase which, coincidentally, is the enzyme responsible for activating ganciclovir through phosphorylation. The third drug (letermovir) inhibits the terminase enzyme complex responsible for packaging unit length DNA into assembling virions.In addition, in a double-blind randomized placebo-controlled trial in neonates with symptomatic congenital CMV infection, a 6-month course of valganciclovir was superior to the standard 6-week course of the same drug. In pregnant women with primary CMV infection, administration of hyperimmune immunoglobulin did not significantly reduce transmission of CMV across the placenta.

SUMMARY

The ability to diagnose CMV infections reliably in different clinical settings through application of molecular laboratory methods has ushered in new ways of evaluating potential new treatments for CMV. Several of these may help control the diseases caused by this important human pathogen.

Long-term neurobiological consequences of early postnatal hCMV-infection in former preterms: a functional MRI study

Early postnatal infection with human cytomegalovirus (hCMV) may contribute to an adverse cognitive outcome in early preterm-born children (PT). We here set out to explore whether long-term neurobiological consequences of such an infection are detectable using fMRI in children and adolescents who were born very preterm and who either did (PThCMV+ ) or did not (PT(hCMV-)) suffer from an early postnatal hCMV-infection, when compared with typically developing healthy control (HC) subjects. Overall, data from 71 children and adolescents could be included, 34 PT (of which 15 were PT(hCMV+) and 19 were PT(hCMV-)) and 37 HC. Using a recently established "dual use" fMRI task, we investigated language and visuospatial functions. There were significant activation differences in the left hippocampus (PT > HC and PT(hCMV+) > HC), and in the right anterior cingulate cortex (PT(hCMV-) > PT(hCMV+)) when performing the language task. Surprisingly, only a small region in the occipital cortex showed a significant activation difference (HC > PT(HCMV-)) when performing the visuospatial task. Targeted analyses revealed differences in gray matter volume, but not density, in several brain regions. Our results suggest that long-term neurobiological consequences of an early postnatal hCMV infection are detectable even in older children and adolescents formerly born very preterm, compatible with a higher effort when performing a cognitive task. This suggests that measures to prevent such an infection are warranted. Furthermore, an interrelation of brain structure and function was detected that may constitute a severe confound when using fMRI to compare structurally differing groups.

Use of ganciclovir in the treatment of acquired cytomegalovirus disease in a preterm infant

The first use of ganciclovir in a preterm infant is reported. The 27 week appropriate-for-gestational-age male infant developed a disseminated cytomegalovirus infection subsequent to a blood transfusion. A daily dose of 10 mg/kg administered intravenously in two divided doses for a total of 14 days was given without adverse clinical or toxic effects. The patient has remained well following discharge from hospital.

Long-term outcome in preterm children with human cytomegalovirus infection transmitted via breast milk

AIM

To investigate neurodevelopmental outcome and hearing in preterm children with breast milk transmitted human cytomegalovirus (HCMV) infection.

METHODS

Forty-one preterm children (born before 32 weeks of gestation or birth weight <1500 g; 20 HCMV positive, 21 HCMV negative) from an original cohort of 44 children were examined at school age. Assessments included neurological examination, assessment of motor [Movement Assessment Battery for Children (M-ABC)] and cognitive function [Kaufman Assessment Battery for Children (K-ABC)], audiological tests and anthropometric measures.

RESULTS

In both groups, irrespective of the presence or absence of a history of HCMV infection, performance in assessments of cognitive and motor function was within the normal range. However, significant differences between the HCMV-positive and the HCMV-negative group were found in both motor and cognitive function, with poorer performance in the HCMV-positive group. There were no significant differences in anthropometric parameters, and all 20 HCMV-positive children had normal hearing function.

CONCLUSIONS

In this study, cognitive and motor function in preterm children with early postnatally acquired HCMV infection transmitted via breast milk was within the normal range. However, the findings suggest that their outcome is poorer than outcome in preterm children without HCMV infection. These findings need to be replicated in larger scale studies.

Maternal cytomegalovirus-specific immune responses and symptomatic postnatal cytomegalovirus transmission in very low-birth-weight preterm infants

INTRODUCTION

Transmission of cytomegalovirus (CMV) via breast milk can lead to severe acute illness in very low-birth-weight (VLBW) preterm infants. Although the majority of CMV-seropositive women shed CMV in milk, symptomatic postnatal infection of VLBW infants occurs infrequently, suggesting that virologic or immunologic factors in milk may be associated with the risk and severity of postnatal CMV infection.

METHODS

We investigated the magnitude of CMV-specific cellular and humoral immune responses in milk of 30 seropositive mothers of VLWB preterm infants and assessed their relationship to milk CMV load and symptomatic CMV transmission.

RESULTS

Milk immunoglobulin G (IgG) avidity was inversely correlated to milk CMV load (r = -0.47; P = .009). However, milk CMV load and CMV-specific cellular and humoral immune responses were similar in mothers of VLBW infants with and those without symptomatic postnatal CMV infection.

CONCLUSIONS

Similar immunologic parameters in milk of CMV-seropositive mothers of VLBW infants with and without symptomatic postnatal CMV infection indicate that screening milk by these parameters may not predict disease risk. However, the inverse correlation between milk CMV IgG avidity and CMV load may suggest that enhancement of maternal CMV-specific IgG responses could aid in reduction of CMV shedding into breast milk.

Breastfeeding and transmission of cytomegalovirus to preterm infants. Case report and kinetic of CMV-DNA in breast milk

Background

Breastfeeding has a major impact on CMV epidemiology. Postnatal CMV reactivation's incidence during lactation is nearby the maternal seroprevalence. Although perinatal CMV infection has practically no consequences in term newborn, it may cause, in some cases, a severe symptomatic disease in preterm newborns.

The aims of the present study are to evaluate the rate and clinical expression of CMV infection breast milk transmitted in preterm infants and to check the safety of the freezing treated breast milk.

Methods

The study included fifty-seven preterm infants and their CMV seropositive mothers. Fresh breast milk samples have been collected from 1^st to 9^th postpartum week. Both fresh breast milk and 72, 96, 120 hours frozen samples have been examined, checking the presence of CMV; urine samples have been tested too.

Results

70.2% of tested mothers showed reactivation of the infection, and CMV-positive breast milk during the six weeks postpartum has been found. However, only one infant was infected by CMV, developing hepatic affection concomitantly with a multi-system involvement, as shown CMV DNA detection in urine, saliva, blood, gastric aspirate, and stools.

Conclusion

Freezing breast milk at -20°C and pasteurization may respectively reduce or eliminate the viral load.

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.

[Review and guidelines on the prevention, diagnosis and treatment of post-natal cytomegalovirus infection]

Postnatal cytomegalovirus (CMV) infection in the newborn can occur from exposure to maternal cervical secretions during birth, ingestion of breast milk, transfusion of blood products or transmission by body fluids of infected people. Breast milk is the main source of infection, given the high rate of CMV-positive mothers excreting CMV in milk. Freezing reduces the risk of CMV transmission by breastfeeding, although it does not eliminate it completely. Pasteurisation prevents such transmission, but it can alter the immunological properties of breast milk. Postnatal CMV infection is usually asymptomatic, as it normally results from viral reactivation in the mother, and the neonate is born with protective antibodies. However, in the very low birth weight premature infant the amount of transferred antibodies is smaller and a symptomatic infection can occur. Symptomatic post-natal CMV infection in the newborn typically causes hepatitis, neutropenia, thrombocytopenia or sepsis-like syndrome. Pneumonitis and enteritis are less common, but very characteristic. Diagnosis is based on urine virus detection at the time of onset of symptoms. Postnatal CMV infection in the newborn generally resolves spontaneously without antiviral treatment. Ganciclovir should be reserved for severe cases. Unlike congenital CMV disease, post-natal CMV infection in the preterm infant does not seem to be associated with hearing loss or abnormal neuro-development in long term follow-up.

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.

Quantitative detection of HCMV-DNA in saliva from infants and breast milk on real-time polymerase chain reaction

BACKGROUND

The role of breast milk in viral transmission has not been fully studied. To determine the effect of breast milk on the establishment of primary human cytomegalovirus (HCMV) infection in term infants, HCMV-DNA was measured in breast milk and infant saliva.

METHODS

The study population consisted of 48 healthy term infants and their mothers. The copy number of HCMV-DNA in the infants' saliva and mothers' milk was measured on quantitative real-time polymerase chain reaction (PCR).

RESULTS

HCMV-DNA was detected in both saliva and breast milk from 21 infant-mother pairs, in milk only from four pairs, in saliva only from 12 pairs, and in neither from 11 pairs. HCMV-DNA was first detected in the saliva of 10 infants at age 4 months, seven infants at 7 months, 13 infants at 10 months, and three infants at 12 months. The viral loads peaked 4-10 months after birth, and thereafter decreased or became negative. The peak copy number and rate of HCMV-DNA detection in saliva were significantly related to peak copy number and rate of detection in the corresponding breast milk.

CONCLUSION

Thus, HCMV passed through breast milk 1-7 months after delivery affects the persistence and level of HCMV-DNA in infant saliva and is the most important route of primary infection.

A haemophagocytic lymphohistiocytosis (HLH)-like picture following breastmilk transmitted cytomegalovirus infection in a preterm infant

Due to septic illness, neutro- and thrombocytopenia, blocked myelopoiesis, CMV-positive breast milk and CMV-pp65 antigen in bone marrow mononuclear cells, CMV-related HLH was presumed in a breast fed neonate (gestational age 24 weeks). Treatment was successful with foscarnet and methylprednisolone. HLH may be a complication of post-natal CMV-infection acquired from breast milk.

Cytomegalovirus transmission to preterm infants during lactation

Breastfeeding has a major impact on HCMV epidemiology. The incidence of postnatal HCMV reactivation during lactation equals the maternal seroprevalence. Infectious virus, viral DNA and RNA can be isolated easily from cell and fat-free milk whey. Early onset of viral DNAlactia and virolactia as well as high viral load in milk whey are maternal risk factors for virus transmission. The dynamics of HCMV reactivation can be described by unimodal kinetics with interindividual variation. Virus reactivation during lactation is a self-limiting local process in the absence of systemic HCMV infection. Preterm infants below 1000g birthweight and a gestational age below 30 weeks may be at high risk of acquiring a symptomatic HCMV infection. Several recent studies described low transmission rates and mostly asymptomatically infected neonates using frozen milk. Despite different freeze-storing procedures, HCMV transmissions occurred, and severe HCMV infections were observed. Few data exist on the long-term outcome of postnatally acquired HCMV infection via breast milk. To substantiate the international debate on the use of native or inactivated milk for feeding of preterm infants, additional data are necessary for better identification of mother-infant-pairs at risk for viral transmission and symptomatic infection early after birth.

Transmission of cytomegalovirus to extremely preterm infants through breast milk

AIM

To evaluate the rate and clinical expression of postnatal cytomegalovirus (CMV) infection transmitted through breast milk in extremely preterm infants.

METHODS

Ten extremely preterm infants and their six mothers were included. Maternal CMV serology was determined. Breast milk samples and urine samples from the infants were screened for CMV. Symptoms and laboratory findings of CMV infected infants were documented. All infants received partly fresh and/or defrosted breast milk.

RESULTS

CMV-DNA was found in breast milk in four of five CMV-seropositive mothers. Two infants were infected by CMV. They were the only infants fed with breast milk positive for viral culture. One infant developed hepatic affection concurrent with viral excretion in urine. This infant was later diagnosed with cystic fibrosis.

CONCLUSION

This study supports that CMV transmission through breast milk can aggravate the clinical course in extremely preterm infants with preexisting hepatic conditions.

Application of UL144 molecular typing to determine epidemiology of cytomegalovirus infections in preterm infants

Sequence analysis of the UL144 gene of human cytomegalovirus (CMV) was used to investigate the epidemiology of CMV infections in preterm infants. Nosocomial transmission of CMV from congenitally infected infant to preterm twins was excluded based on distinct molecular profiles of CMV strains. Indistinguishable molecular profiles between strains from the mother and the infant indicated postnatal acquisition of CMV through breastfeeding.

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

Since the recognition in the 1960s that human cytomegalovirus (HCMV) infections could be transmitted by breast milk, there has been relatively little attention paid to the potential medical consequences of such infections. Indeed, since HCMV infections acquired by healthy newborn infants appear to be largely asymptomatic in nature, there has been no real incentive to develop or implement strategies to prevent transmission by this route. However, recent studies have identified a significant risk for low-birth weight, premature infants for the development of HCMV disease following acquisition of infection via breast milk. Such infections may cause considerable short-term morbidity and, in some cases, severe, life-threatening illness. There is little consensus amongst neonatologists on the approach to prevention and management of such infections. This review summarises the epidemiology and natural history of HCMV infections acquired via breast milk, and outlines available strategies for prevention and management of such infections, as well as opportunities for future clinical research on this understudied topic.

[Pilot epidemiologic study of transmission of cytomegalovirus from mother to preterm infant by breastfeeding]

Transmission of cytomegalovirus (CMV) infection from mothers to preterm infants during breastfeeding may be symptomatic and long term consequences are unknown. This study evaluated the kinetics of CMV load in breastmilk and the rate of postnatal CMV transmission via breastmilk from mothers to their preterm infants.

METHODS

Prospective study of mother-child pairs after preterm delivery before 33 weeks. Exclusion of donor breast milk and of CMV-seropositive blood products. Material used was maternal CMV serostatus, ear swab of the infant at birth, weekly screened breast milk and children's urine by rapid viral culture.

RESULTS

During a 5-month period 28 mother-infant pairs with 34 preterm infants were studied. Eighteen women (64.3%) were CMV-seronegative at birth; breastmilk samples and the infants' urine remained CMV-negative. Eight of the 10 seropositive mothers, who had 11 preterm infants, excreted CMV into breast milk (80%). CMV excretion into breast milk was detected during the first week after delivery in 66% cases and was at its peaked between 3 to 5 weeks after delivery. Out of the 7 CMV-exposed infants, CMV transmission was confirmed in only one asymptomatic case. Total quantity of breast milk intake did not seem discriminative for CMV transmission.

CONCLUSION

In CMV-seropositive mothers of preterm infants a high incidence of CMV excretion into breast milk was detected. Despite this high rate, symptomatic infection did not occur. However, potential risk and severity of infection may be difficult to establish. Because breastfeeding is beneficial, new procedures for gentle virus inactivation of seropositive breast milk should be assessed.

Case-control study of symptoms and neonatal outcome of human milk-transmitted cytomegalovirus infection in premature infants

OBJECTIVE

Preterm infants are at risk of acquiring human cytomegalovirus (CMV) infection through breast milk transmission, possibly leading to serious symptoms, as suggested by previous studies. Over a period of 8.5 years, we compared infants infected postnatally with CMV with noninfected controls to determine whether CMV infection transmitted through breast milk poses serious acute risks.

STUDY DESIGN

CMV monitoring included maternal serologic testing and biweekly viral culture and polymerase chain reaction in breast milk and infant urine. Clinical and laboratory test findings were assessed retrospectively in infected infants and controls matched for gestational age during the initial hospital stay.

RESULTS

Forty CMV-infected infants met the study criteria. They had lower minimal platelet and neutrophil counts and a higher frequency of C-reactive protein (CRP) elevations to 10 to 20 mg/L than their matched controls (P < or = .001). But no association of CMV infection with bronchopulmonary dysplasia, necrotizing enterocolitis, growth, or CRP elevations to > 20 mg/L was found. Cholestasis appeared in 3 infants in the CMV-infected group, but disappeared within 10 weeks.

CONCLUSIONS

Neonatal symptoms related to postnatal CMV infection were transient and had no affect on neonatal outcome in these infants, in contrast with uncontrolled reports. Whether withholding or pasteurizing breast milk is warranted, however, depends on long-term outcome.

Transfusion-related cytomegalovirus infection among very low birth weight infants in an endemic area

This study investigated the incidence of acquired cytomegalovirus (CMV) infection in very low birth weight infants (VLBWI) given CMV seropositive blood, and sought to determine whether filtering and irradiation of blood products could help prevent CMV infection and the time required to clear passively-derived anti-CMV IgG among 80 VLBWI transfused with filtered-irradiated blood, 20 VLBWI transfused with nonfiltered- nonirradiated blood and 26 nontransfused VLBWI. CMV IgG and IgM values were obtained from all blood products prior to transfusions, and from VLBWI at birth until the infants became seronegative. Urine was obtained for CMV culture at birth and every 3-4 weeks until 12 weeks after the final transfusion. The incidence of CMV IgG seropositivity among the 126 infants at birth and the blood products given were 96% and 95%, respectively. The incidence of acquired CMV infection was 4/100 (4%) in the transfused group: 2/80 (2.5%) and 2/20 (10%) in the filtered-irradiated and nonfiltered-nonirradiated transfusion groups, respectively. Approximately 9-10 months elapsed to clear passively acquired CMV IgG. The irradiation and filtering of the blood products did not seem to decrease the transfusion-related CMV infection rate in Korea among VLBWI, however, further validation is recommended in a larger cohort of infants.

Cytomegalovirus in human breast milk: risk to the premature infant

Human cytomegalovirus (HCMV) can be transmitted through breast milk to neonates. Although healthy full-term infants rarely develop symptoms of CMV infection; premature or low-birth-weight infants can experience symptomatic infection that is occasionally severe. There is limited information on the long-term effects of postnatal CMV infection in premature infants, suggesting that these infants do not develop cognitive function delays or hearing loss, although those with intrapartum infection do. Readily available methods of treating breast milk to inactivate the CMV either diminish the immunologic and nutritive benefits of breast milk or incompletely inactivate the virus. This review considers the data on measuring CMV in breast milk, the recent clinical studies on CMV transmission via breast milk, reported methods of inactivation of CMV in breast milk, and immunologic factors that may play a role in transmission. CMV-IVIG treatment needs further evaluation but appears promising. Recommendations are made to help address the issue of CMV transmission to premature infants in clinical practice in the neonatal intensive care unit (NICU).

Breast milk and cytomegalovirus infection in preterm infants

The incidence of postnatal human cytomegalovirus (HCMV) reactivation during lactation equals the maternal seroprevalence. Infectious virus, viral DNA and RNA can be isolated from cells and fat free milk whey. Early onset of viral DNAlactia and virolactia as well as high viral load in milk whey are maternal risk factors for virus transmission. Preterm infants below 1000 g birthweight and a gestational age below 30 weeks may be at high risk of acquiring a symptomatic HCMV infection. Several recent studies using frozen milk for feeding describe low transmission rates and mostly asymptomatically infected neonates. However despite different freeze-storing procedures HCMV transmission occurred and severe HCMV infections were observed. Only few data exist on the long-term outcome of postnatally acquired HCMV infection via breast milk. Additional long-term outcome studies are needed. The newly developed short-term pasteurisation may be a reliable alternative to freezing and Holder pasteurisation, since important milk constituents are conserved.

Cytomegalovirus

PURPOSE OF REVIEW

To identify recent developments in the management of congenital cytomegalovirus infection which continues to exact a heavy toll on the developing central nervous system.

RECENT FINDINGS

A major advance is the publication of a randomized controlled trial showing that hearing loss is significantly decreased by ganciclovir. This treatment should now be offered to all neonates who would have met the eligibility criteria of the trial, that is proven congenital infection with central nervous system involvement when treatment is begun within 1 month of birth. A second major advance is the use of stored dried blood spots to detect cytomegalovirus DNA and so differentiate congenital infection from perinatal infection. This approach has the potential to diagnose a proportion of cases of hearing loss and mental retardation which are currently labelled idiopathic. A third major advance is the clinical evaluation of vaccines against cytomegalovirus. Experiments with guinea pig cytomegalovirus show reduced fetal mortality and congenital infection among dams given vaccines containing the glycoprotein B of the virus. A different vaccine glycoprotein B construct has been shown to be immunogenic and well tolerated in healthy adult and paediatric humans. Recent reviews from the Institute of Medicine and the National Vaccine Advisory Committee emphasize the financial and humanitarian justifications for developing cytomegalovirus vaccines as a high priority.

SUMMARY

Substantial progress has recently been made in diagnosis and treatment. If additional financial support were to be made available to evaluate existing vaccine candidates in controlled clinical trials, congenital cytomegalovirus could potentially become a vaccine-preventable disease.

Incidence and clinical manifestations of breast milk-acquired Cytomegalovirus infection in low birth weight infants

OBJECTIVES

To determine the incidence and clinical manifestations of human breast milk (HMB)-associated acquired cytomegalovirus (CMV) infection in small premature infants.

STUDY DESIGN

A prospective study of premature infants born at or prior to 32 weeks gestation, and or infants weighing 1500 g or less at birth. The babies were divided into two groups: Group 1 included babies of CMV seropositive mothers who received HBM throughout the study period. Group 2 included babies of seronegative mothers or babies that did not receive HBM at all. Urine sample were obtained once weekly from birth until the age of 8 weeks or until discharge and were tested for the presence of CMV-DNA by PCR.

RESULTS

Four of 70 infants from group 1 (5.7%, 95% CI, 0 to 11%) acquired CMV infection between the ages of 3 and 7 weeks as compared to none of 26 babies in group 2. Only one infected baby had severe CMV disease with complete recovery.

CONCLUSION

The relative incidence of HBM-associated CMV infection and the severity of HBM-associated CMV disease in premature infants are low.

Human cytomegalovirus reactivation during lactation and mother-to-child transmission in preterm infants

In a clinical trial, the incidence of cytomegalovirus reactivation in breastfeeding mothers and transmission to their preterm infants were studied. Breast milk from 73 mothers as well as urine and tracheal and pharyngeal aspirates from their 89 infants were screened weekly for human cytomegalovirus (HCMV) DNA during the first 2 months after delivery. Of the 73 mothers, 48 (66%) were positive for HCMV DNA in the lactating breast. HCMV reactivation could be confirmed for 19 of 20 (95%) immunoglobulin G-positive mothers. Of the eight immunoglobulin G-negative mothers one was positive for HCMV DNA in breast milk. In only 2 out of 13 seropositive mothers with HCMV DNA in breast milk could viral DNA be detected in the peripheral blood. HCMV mother-to-child transmission was concluded for 20 of the 48 (42%) mothers positive for DNA or 7 of 19 (37%) seropositive for HCMV and positive for HCMV DNA in breast milk and one of one mother seronegative for HCMV but positive for HCMV DNA in breast milk. One mother transmitted the virus to her twins. In addition, one infant acquired postnatal HCMV infection despite the mother's being negative for HCMV DNA in breast milk; altogether, we found 22 infants with HCMV infection. In 13 of these 22 infants, virus infection occurred definitively postnatally; two of them developed severe symptomatic HCMV infection. HCMV-infected infants demonstrated higher incidences of amniotic infection, respiratory distress syndrome, bronchopulmonary dysplasia, and retinopathia praenatalis than noninfected infants, however, the differences were not statistically significant. In summary, our study confirmed a very high incidence of HCMV reactivation in mothers during lactation and a significant risk of transmission to preterm infants with the possibility of severe disease in these babies.

Cytomegalovirus transmission to extremely low-birthweight infants through breast milk

AIM

To determine the incidence, timing and clinical significance of acquired postnatal cytomegalovirus (CMV) in extremely low-birthweight (ELBW) infants.

METHODS

Prospective, longitudinal surveillance study. ELBW infants were recruited in the first week of life. Maternal blood was tested for CMV-specific IgG antibodies. Weekly urine samples were obtained from infants for CMV culture and rapid antigen testing. Data were collected regarding clinical course and breast milk intake.

RESULTS

Of 181 eligible infants, 119 infants, born to 101 mothers, were enrolled. Eighty of the 101 mothers had their serum checked for CMV status. Seventy percent of those tested were seropositive for CMV. Of the 65 infants born to seropositive mothers, 94% received breast milk during their hospital stay. Complete urine collection was obtained in 92 infants. CMV was cultured from the urine of only four infants, all of whom were born to seropositive mothers. Only one of these four infants was symptomatic. The range at which CMV was first detected was between 48 and 72 postnatal days of age.

CONCLUSIONS

Despite a very high CMV seropositivity rate in mothers of ELBW infants, and the previously reported high rate of CMV excretion into breast milk, the incidence of postnatal CMV transmission was extremely low in our study.

Perinatal or early-postnatal cytomegalovirus infection in preterm infants under 34 weeks gestation born to CMV-seropositive mothers within a high-seroprevalence population

In a prospective study, we evaluated the frequency, correlates, and clinical significance of perinatal or early-postnatal cytomegalovirus (CMV) infection in <34-week-gestation infants (n=95) born to CMV-seropositive mothers. None had congenital CMV infection. Overall, 21 (22.1%; 95% CI=14.2-31.8) infants were found to be infected; 10 excreted CMV at <60 days, and 11 had later excretion. Blood transfusion, birth weight, and vaginal delivery were not associated factors. Receiving natural breast milk within the first 30 days (OR=4.5, P=.02) or for >30 days (OR=7.9, P <.01) was associated with infection. Only one (4.8%) of the infected infants was symptomatic. For <34-week-gestation infants, frequency of perinatal and early-postnatal CMV infection is high. Early or prolonged exposure to breast milk is an associated factor. However, most infections are asymptomatic, indicating that CMV infection in preterm infants within such a population is a serious problem infrequently.

Transmission of cytomegalovirus from mothers to preterm infants by breast milk

OBJECTIVES

To assess the risk of transmission of cytomegalovirus (CMV) by breast milk from CMV-seropositive mothers to their breast-fed preterm infants and to evaluate their outcome.

PATIENTS AND METHODS

The study population comprised breast-fed preterm infants with a birth weight of <1,500 g and gestational age of <35 weeks. Venous blood samples from the mothers and infants were tested for CMV IgG and IgM antibodies on the 5th and 30th day after birth. Breast milk was obtained for CMV DNA detection by polymerase chain reaction and viral culture on the 5th day and on the 3rd, 6th and 12th week. Urine samples of the babies were collected at the same time for CMV culture. Neurodevelopmental assessment was done at 6 months of age, corrected for preterm birth.

RESULTS

Thirty-eight mothers and 42 infants (including 4 sets of twins) were enrolled in the study. A mother-infant pair was excluded because of inadequate breast milk collection. Thirty-six mothers (97.3%) were CMV-seropositive. CMV DNA of breast milk was detected in 35 seropositive mothers. Six infants of 5 mothers were infected (infected group) at a mean of 77 days after birth, and 34 infants of 31 mothers were not (noninfected group). In all the mothers of the infected group, CMV virus could be cultured from the milk whey. The average maternal CMV IgG on day 5 after delivery was higher in the infected than in the noninfected group. Sepsis-like symptoms and hyperbilirubinemia were more frequently noted in the infected infants than in the noninfected, but the difference was not statistically significant. Neurodevelopmental outcome did not significantly differ between the 2 groups.

CONCLUSIONS

The risk of CMV infection in breast-fed premature infants was highest when the mothers shed viable virus in their breast milk. These mothers had high CMV IgG, which may help identify those mother-infant pairs at risk. Inactivation of the virus in milk by freezing may be a way of reducing the transmission of this virus via breast milk.

An animal model of neonatal cytomegalovirus infection

Cytomegalovirus (CMV) is the most common cause of congenital infection in the developed world and can lead to a life-threatening disease. We therefore developed an animal model to evaluate candidate anti-CMV drugs and to further define the pathogenesis of CMV infections. Newborn guinea pigs were infected by intraperitoneal administration of 10(6) pfu of a virulent salivary gland (SG) passaged guinea pig CMV (gpCMV) within 48 h of birth. Inoculation of animals produced 50% overall mortality. A lack of weight gain was also a hallmark of infection. By day 14 after inoculation the weight of gpCMV-infected animals was significantly less than controls (152.9+/-45 g versus 254.7+/-38.5 g, P<0.0001). The most consistent isolation and highest titers of virus were found in the liver and spleen early while lung titers were maximal at day 10. A quantitative competitive PCR (qcPCR) assay confirmed the presence of a high CMV viral load in infected organs. Antiviral treatment with cyclic HPMPC (cHPMPC) for 7 days significantly reduced mortality (1/20 versus 14/20, P<0.001) and viral replication but did not improve weight gain. This model should be useful for further evaluations of the pathogenesis of CMV infections and for evaluation of antiviral drugs and vaccines.

Evaluation of cytomegalovirus infections transmitted via breast milk in preterm infants with a real-time polymerase chain reaction assay

OBJECTIVE

Preterm infants are at greater risk of symptomatic cytomegalovirus (CMV) infection than term infants. Breast milk is the main source of perinatal CMV infections. This study evaluated the kinetics of CMV load in breast milk and the rate of postnatal CMV transmission via breast milk from mothers to their preterm infants.

METHODS

This was a prospective study of 30 mothers and their 43 preterm infants. The infants either had a gestational age of <34 weeks or weighed <2000 g at birth. Breast milk, serum, and urine samples were collected every 2 weeks until discharge, and screened for CMV infection using a real-time PCR assay. Most of the breast milk had been preserved at -20 degrees C before feeding to the preterm infants.

RESULTS

Twenty-four mothers (24 of 30, 80%), who had 34 preterm infants, were CMV immunoglobulin G positive. Twenty-one (87.5%) of the 24 seropositive mothers, who had 30 preterm infants, had detectable CMV deoxyribonucleic acid (DNA) in breast milk during the study period. Most breast milk became positive for CMV DNA 2 weeks after delivery. Viral DNA copy numbers increased until they peaked at 4 to 6 weeks. Afterward, the CMV DNA copy numbers decreased. Of the 30 infants who were fed CMV DNA-positive breast milk, CMV infection was confirmed in 3 infants. However, they had no clinical symptoms of CMV infection.

CONCLUSIONS

Despite the high rate of CMV DNA in breast milk, symptomatic infections in the preterm infants did not occur. These results might be associated with the method of breast milk preservation and the population we studied. CMV infections transmitted via breast milk feeding did not have much impact on preterm infants in our institutes.

Placental transfer of naturally acquired, maternal cytomegalovirus antibodies in term and preterm neonates

Maternal antibodies may protect the fetus and neonate against severe forms of CMV-caused disease, therefore this study investigated the efficiency of the placental transfer of naturally acquired, maternal total anti-cytomegalovirus (CMV) IgG and neutralizing antibodies at different gestational ages. The study was conducted on 182 healthy CMV-seropositive Brazilian mothers and their 196 infants who were not infected congenitally with CMV, as determined by CMV detection in urine. The study groups were composed of 44 infants aged 28-30 weeks; 51 infants aged 31-33 weeks; 62 infants aged 34-36 weeks, and 39 infants of gestational age > or = 37 weeks. Quantitative detection of total CMV IgG was carried out using EIA and virus neutralizing titers were determined by a microneutralization assay in sera from mothers and infants. CMV IgG levels and neutralizing titers of the infants correlated with maternal levels (r=0.873 and r=0.841, respectively). The efficiency of placental transfer of these antibodies was enhanced significantly as gestation progressed until 34-36 weeks, when values similar to those of full-term infants (90-100%) were found. Transfer ratios were significantly higher for neutralizing compared to total CMV IgG antibodies at gestational age 31-33 weeks (100% vs. 84%, respectively) and at gestational age 28-30 weeks (75% vs. 60%, respectively). We conclude that placental transfer of naturally acquired maternal CMV neutralizing and total CMV IgG antibodies are similarly efficient above 34 weeks of gestational age. At less than 34 weeks of gestational age, transfer of neutralizing antibodies may be favored and these antibodies reach the neonatal serum of 99% of these premature infants.

Cytomegalovirus transmission from breast milk in premature babies: does it matter?

There is evidence that CMV is commonly present in breast milk and is often transmitted to babies. CMV infection acquired postnatally can cause serious disease in very premature babies. Interventions to remove CMV from breast milk are possible but may damage other important constituents.

Human adenovirus and human cytomegalovirus infections in preterm newborns: no association with bronchopulmonary dysplasia

Connatal infection with human adenovirus (HAdV) has been recently proposed as a cofactor for the development of bronchopulmonary dysplasia (BPD) in preterm infants [Couroucli et al. 2000 Pediatr Res 47:225-232]. In another study, BPD was associated with an increased incidence of human cytomegalovirus (HCMV) infection [Sawyer et al. 1987 Am J Dis Child 141:303-305]. During a 18-mo study period, we investigated tracheal aspirates or pharyngeal aspirates and urine samples collected during the first month of life from 66 preterm newborns with very low birth weight (< or =1.500 g) for replication-potent HAdV as well as for adenoviral and HCMV DNA by virus culture and qualitative DNA PCR. Thus, our study included not only prenatal but also peri- and postnatal infections. Thirty-seven percent (24/66) of infants developed BPD(1), as defined by persistent oxygen dependency at day 28 of life. Replication-potent HAdV and/or adenoviral DNA could be detected repeatedly in tracheal aspirates/pharyngeal aspirates and/or urine from 20% (13/66) of preterm infants. Seventeen percent (4/24) of infants in the BPD(1) group and 21% (9/42) of infants in the non-BPD group had an HAdV infection, indicating that in our study the very recently proposed association between HAdV infection of the lung and BPD could not be confirmed. For comparison, active HCMV infection was diagnosed in 18% (12/66) of infants, 3 of which developed HCMV disease. 29% (7/24) in the BPD(1) group and 12% (5/42) in the non-BPD group were positive for HCMV. Again, there was no statistically significant association between HCMV infection and BPD. In summary, our findings indicate that HAdV and HCMV infection are frequent in preterm newborns with very low birth weight; however, a causal association with the development of BPD seems unlikely.

Cytomegalovirus infection of extremely low-birth weight infants via breast milk

In addition to seroprevalence and transmission rate, the clinical symptoms of postnatal cytomegalovirus (CMV) infection in infants with a very low birth weight (VLBW; <1500 g; <32 weeks gestational age at birth) were assessed in a 3-year prospective study. CMV monitoring included serologic testing (of the mother and child) and virus culture and PCR (of samples of both breast milk and the infant's urine). Within 3 weeks of the initial virus detection in the infant, clinical and laboratory parameters were evaluated. Of 170 infants, no CMV transmission was found in the 80 infants of seronegative mothers and in the 3 infants of seropositive mothers who did not shed CMV DNA into breast milk. Transmission occurred in 33 of the 87 CMV-exposed infants, 16 of whom presented with such symptoms as hepatopathy, neutropenia, thrombocytopenia, and sepsis-like deterioration. Low birth weight and early postnatal virus transmission were risk factors for symptomatic infection. VLBW infants of CMV-seropositive mothers are at high risk of acquiring a symptomatic CMV infection postnatally via breast milk.

Epidemiology of transmission of cytomegalovirus from mother to preterm infant by breastfeeding

BACKGROUND

Breastfeeding practices strongly influence the epidemiology of human cytomegalovirus infection. By contrast with term neonates, few data are available on transmission of infection from mothers to preterm infants during breastfeeding.

METHODS

151 mothers and their 176 preterm infants (gestational age at birth <32 weeks or birthweight <1500 g) were prospectively screened for cytomegalovirus infection by serology, virus culture, and PCR. The roles of cell-free and cell-associated cytomegalovirus excretion during lactation were analysed longitudinally in relation to transmission, by maximum-likelihood estimates.

FINDINGS

Of the 69 seronegative breastfeeding control mothers, none had detectable cytomegalovirus DNA in breastmilk and none of their 80 infants shed the virus in urine. The proportion of cytomegalovirus reactivation in seropositive breastfeeding mothers was 96% (73 of 76). The early appearance of viral DNA in milk whey (median 3.5 days post partum in transmitters; 8 days in non-transmitters; p=0.025) and infectious virus in milk whey (10 days and 16 days, respectively; p=0.005) were risk factors for transmission. The cumulative rate of transmission was 37% (27 of 73 mothers; 33 infants). The infection of the neonates had a mean incubation time of 42 days (95% CI 28-69). About 50% of the infected infants had no symptoms, but four had sepsis-like symptoms.

INTERPRETATION

The proportion of cytomegalovirus reactivation during lactation almost equals maternal seroprevalence. Breastfeeding as a source of postnatal cytomegalovirus infection in preterm infants has been underestimated and may be associated with a symptomatic infection.

Given the benefits of breastfeeding, what contraindications exist?

Breastfeeding is not contraindicated in association with environmental hazards in the United States under ordinary circumstances. Unusual massive exposure should be assessed on an individual basis. In the face of any possible contraindication to breastfeeding, the tremendous benefits of being breastfed should be compared with the theoretic risk for the hazard involved and a decision made on an individual basis.

A practical approach to evaluating and treating neutropenia in the neonatal intensive care unit

Neutropenia is a relatively common problem in the NICU, recognized in as many as 8% of patients at some time during their hospital stay. In most instances, neutropenia among NICU patients is of short duration and has little influence on outcome. In other cases it is prolonged and severe, and constitutes a serious antimicrobial defense deficiency. When a neonatologist discovers a low blood neutrophil count, choices must be made regarding further evaluation and treatment. The authors hope that the information provided in this article is useful in making these choices.