Congenital cytomegalovirus infection in San Luis Potosi, Mexico

Incidence of congenital and postnatal cytomegalovirus infection during the first year of life in Mexican preterm infants

Cytomegalovirus infection occurs commonly during infancy. Postnatal infection in term infants is usually asymptomatic; however, infection in preterm infants can be associated with clinical manifestations during the neonatal period. Nevertheless, few studies to assess the frequency of cytomegalovirus infection in preterm infants have been performed outside of high-income countries. We analyzed the incidence of congenital and postnatal cytomegalovirus infection in a cohort of preterm infants. Cytomegalovirus infection was detected during the neonatal period in four of 178 infants; in three of them the virus was detected during the first three weeks of life and, therefore, congenital infection was confirmed (1.7% incidence). Postnatal infection was detected in 44 (36.4%) of 121 infants who were assessed after discharge from the neonatal intensive care unit. Cytomegalovirus infection was significantly associated to duration of breast feeding. In addition, we characterized cytomegalovirus strains detected in infants together with sequences available at GenBank, based on sequences of the UL18 gene. Cytomegalovirus UL18-sequences clustered in five distinct clades (A-E), and sequences obtained from infants in our study were distributed in four of the five clades; 44.4% of these sequences were included in clade E. Breastfeeding duration was shorter in average (5.6 months) in infants with sequences in clade E compared to infants with sequences in the other three clades (8.2 months; P=0.07). In conclusion, we provide information regarding the high incidence of cytomegalovirus infection in preterm infants. Further studies are warranted to assess if cytomegalovirus strain characteristics are associated with the risk of infection acquisition during infancy. This article is protected by copyright. All rights reserved.

Congenital Cytomegalovirus Infection Burden and Epidemiologic Risk Factors in Countries With Universal Screening: A Systematic Review and Meta-analysis

IMPORTANCE

Congenital cytomegalovirus (cCMV) infection is the most common congenital infection and the leading acquired cause of developmental disabilities and sensorineural deafness, yet a reliable assessment of the infection burden is lacking.

OBJECTIVES

To estimate the birth prevalence of cCMV in low- and middle-income countries (LMICs) and high-income countries (HICs), characterize the rate by screening methods, and delineate associated risk factors of the infection.

DATA SOURCES

MEDLINE/PubMed, Scopus, and Cochrane Database of Systematic Reviews databases were searched from January 1, 1960, to March 1, 2021, and a total of 1322 studies were identified.

STUDY SELECTION

Studies that provided data on the prevalence of cCMV derived from universal screening of infants younger than 3 weeks were included. Targeted screening studies were excluded.

DATA EXTRACTION AND SYNTHESIS

Preferred Reporting Items for Systematic Reviews and Meta-analyses guideline was followed. Extraction was performed independently by 3 reviewers. Quality was assessed using the Newcastle-Ottawa Scale for cohort studies. Random-effects meta-analysis was undertaken. Metaregression was conducted to evaluate the association of sociodemographic characteristics, maternal seroprevalence, population-level HIV prevalence, and screening methods with the prevalence of cCMV.

MAIN OUTCOMES AND MEASURES

Birth prevalence of cCMV ascertained through universal screening of infants younger than 3 weeks for CMV from urine, saliva, or blood samples.

RESULTS

Seventy-seven studies comprising 515 646 infants met the inclusion criteria from countries representative of each World Bank income level. The estimated pooled overall prevalence of cCMV was 0.67% (95% CI, 0.54%-0.83%). The pooled birth prevalence of cCMV was 3-fold greater in LMICs (1.42%; 95% CI, 0.97%-2.08%; n = 23 studies) than in HICs (0.48%; 95% CI, 0.40%-0.59%, n = 54 studies). Screening methods with blood samples demonstrated lower rates of cCMV than urine or saliva samples (odds ratio [OR], 0.38; 95% CI, 0.23-0.66). Higher maternal CMV seroprevalence (OR, 1.19; 95% CI, 1.11-1.28), higher population-level HIV prevalence (OR, 1.22; 95% CI, 1.05-1.40), lower socioeconomic status (OR, 3.03; 95% CI, 2.05-4.47), and younger mean maternal age (OR, 0.85; 95% CI, 0.78-0.92, older age was associated with lower rates) were associated with higher rates of cCMV.

CONCLUSIONS AND RELEVANCE

In this meta-analysis, LMICs appeared to incur the most significant infection burden. Lower rates of cCMV were reported by studies using only blood or serum as a screening method.

The prevalence and demographic features of congenital cytomegalovirus infection in an urban area of East Asia: A population-based study

Congenital cytomegalovirus (cCMV) infection is the leading environmental cause of childhood hearing impairment. However, its significance remains largely undocumented in many regions of the world. The purpose of this study was to investigate the prevalence and clinical features of cCMV infection in East Asia. Neonates born at a municipal hospital in Taipei were prospectively recruited and underwent concurrent hearing and CMV screenings. Those who failed the hearing screening or screened positive for CMV were subjected to a focused audiological and/or virological surveillance. The characteristics of the newborns and their mothers were compared between the CMV-positive and CMV-negative groups. Of the 1,532 newborns who underwent concurrent hearing and CMV screenings, seven (0.46%) were positive for cCMV infection. All seven CMV-positive newborns were asymptomatic at birth, and none of them developed hearing or other symptoms during a follow-up period of 14.4±6.3 months. The mothers of the CMV-positive newborns demonstrated higher gravidity (2.4 ± 1.4 vs. 2.1 ± 1.2) and parity (2.0 ± 1.2 vs. 1.6 ± 0.7) than those in the CMV-negative group; however, the difference did not reach statistical significance. The prevalence of cCMV infection in Taipei newborns was 0.46%, which is slightly lower than that of other populations and that of a previous report in the Taiwanese population. The relatively low prevalence in this study might be attributed to the improved public health system and decreased fertility rate in Taiwan.

Natural History of Congenital Cytomegalovirus Infection in Highly Seropositive Populations

Maternal preconceptional cytomegalovirus (CMV) immunity does not protect the fetus from acquiring congenital CMV infection (cCMV). Nonprimary infections due to recurrence of latent infections or reinfection with new virus strains during pregnancy can result in fetal infection. Because the prevalence of cCMV increases with increasing maternal CMV seroprevalence, the vast majority of the cases of cCMV throughout the world follow nonprimary maternal infections and is more common in individuals of lower socioeconomic background. Horizontal exposures to persons shedding virus in bodily secretions (young children, sexual activity, household crowding, low income) probably increase the risk of acquisition of an exogenous nonprimary CMV infection and fetal transmission. In addition, more frequent acquisition of new antibody reactivities in transmitter mothers suggest that maternal reinfection by new viral strains could be a major source of congenital infection in such populations. However, the exact frequency of CMV nonprimary infection in seroimmune women during pregnancy and the rate of intrauterine transmission in these women are yet to be defined. Usually, the birth prevalence of cCMV is high (≥7:1000) in highly seropositive populations. There is increasing evidence that the frequency and severity of the clinical and laboratory abnormalities in infants with congenital CMV infection born to mothers with nonprimary CMV infection are similar to infants born after a primary maternal infection. This is particularly true for sensorineural hearing loss, which contributes to one third of all early-onset hearing loss in seropositive populations. This brief overview will discuss the need for more research to better clarify the natural history of cCMV in highly seropositive populations, which, in almost all populations, remains incompletely defined.

Congenital cytomegalovirus infection

Each year, thousands of children are born with or develop permanent disabilities such as hearing loss, vision loss, motor and cognitive deficits from congenital CMV infection (cCMV). However, awareness of cCMV and its associated sequelae is very low in pregnant women and healthcare providers. Both targeted and universal approaches to screen newborns for CMV infection are now achievable due to recent scientific advances including the development of a rapid, high-throughput method for detecting CMV in saliva, the efficacy of antiviral treatment in symptomatic infants, and the demonstration of cost effectiveness of CMV screening. Future studies are needed to address gaps in our understanding on the role of non-primary maternal CMV infections, the evaluation of antiviral treatment in asymptomatic infants, and the implementation of prevention strategies for cCMV.

Advancing Our Understanding of Protective Maternal Immunity as a Guide for Development of Vaccines To Reduce Congenital Cytomegalovirus Infections

Human cytomegalovirus (HCMV) is the most common congenitally transmitted pathogen worldwide, impacting an estimated 1 million newborns annually. Congenital HCMV (cCMV) infection is a major global contributor to long-term neurologic deficits, including deafness, microcephaly, and neurodevelopmental delay, as well as to fetal loss and occasional infant mortality. Accordingly, design of a maternal vaccine to prevent cCMV continues to be a top public health priority. Nevertheless, we remain without a licensed vaccine. Maternal immunity provides partial protection, as the risk of vertical HCMV transmission from chronically infected mothers is reduced compared to settings in which the mother is newly infected during pregnancy. Therefore, an understanding of the maternal immune correlates of protection against cCMV is critical to informing design of an efficacious maternal vaccine. Although vaccine development is being assiduously pursued by a large number of pharmaceutical manufacturers, biotechnology organizations, and academic researchers, some pessimism has been expressed regarding the issue of whether a vaccine to protect against cCMV is possible. This pessimism is based on observations that natural immunity is not completely protective against maternal reinfection and congenital transmission. However, we assert that optimism regarding vaccine development is indeed justified, on the basis of accruing evidence of immune correlates of protection-readily achievable by vaccination-that are associated with reduced transmission of HCMV to the fetus in seronegative women. In light of the substantial burden on society conferred by cCMV infection, even a modest reduction in the occurrence of this fetal disease is an important public health goal and justifies aggressive clinical evaluation of vaccines currently in the pipeline.

Killer-cell immunoglobulin-like receptors and cytomegalovirus reactivation during late pregnancy

Human cytomegalovirus (CMV) represents an important public health concern as it is associated with severe morbidity and mortality in transplant recipients, HIV-infected individuals and pregnant women given the risk of congenital infection. Congenital CMV is a leading cause of neurological sequelae, developmental delay and birth defects worldwide. Cytomegalovirus can be transmitted to the foetus following maternal infection or reactivation. NK cells expressing killer-cell immunoglobulin-like receptors (KIR) are part of the innate immune system and the first line of defence against viral incursions. Previous reports have shown that KIR genes are associated with CMV infections in the post-transplant setting. In this study, we set out to determine whether a protective effect of KIR genes over CMV infection is seen in Mexican pregnant women. Cytomegalovirus infection was assessed through nucleic acid testing in 200 pregnant women and 600 healthy blood donors comprising the Mexican mestizo reference population. Killer-cell immunoglobulin-like receptors and HLA-C genotypes were obtained from 200 pregnant women and 300 reference samples using a comprehensive PCR-SSP approach. We observed statistically lower carrier frequencies of cB03|tA01 gene-content haplotype, of cB03 haplotype motif, of the KIR2DL5 + 2DS3/2DS5 gene pair and of KIR2DL5 amongst CMV-positive pregnant women in comparison with those CMV negative. None of these were associated with CMV status in the reference population. Logistic regression analysis revealed that the most important factor determining CMV status during third-trimester pregnancies was the KIR2DL5 + 2DS3/2DS5 gene pair (OR 0.376 (95%CI 0.174, 0.811, P = 0.013). Our results indicate that CMV-protective KIR gene associations described in Caucasoid populations are also present in the genetically distinct Mexican mestizo population. Our results suggest that certain KIR gene combinations provide protection against CMV infections occurring during late-term pregnancies, a finding of utmost epidemiological importance given its implication with congenital CMV infections.

Systematic review of the birth prevalence of congenital cytomegalovirus infection in developing countries

BACKGROUND

Congenital cytomegalovirus (CMV) infection is the leading infectious cause of congenital hearing loss and neurodevelopmental disability in developed countries. Information on congenital CMV infection in developing countries appears to be lacking.

METHODS

We conducted a systematic literature review to identify studies from developing countries with population-based samples of at least 300 infants that used laboratory methods established as reliable for the diagnosis of congenital CMV infection.

RESULTS

Most studies were excluded due to biased samples or inadequate diagnostic methods; consequently the search identified just 11 studies that were from Africa, Asia, and Latin America. The number of newborns tested ranged from 317 to 12 195. Maternal CMV seroprevalence ranged from 84% to 100%. CMV birth prevalence varied from 0.6% to 6.1%. CMV-associated impairments were not documented in most studies.

CONCLUSIONS

Birth prevalence ranges were higher than for Europe and North America, as expected based on the higher maternal CMV seroprevalence. With very limited data available on sequelae, the disease burden of congenital CMV in developing countries remains largely unknown at this time.

Cytomegalovirus infection in infants admitted to a neonatal intensive care unit

OBJECTIVES

To determine the incidence of congenital cytomegalovirus (CMV) infection and the frequency of postnatal infection in a neonatal intensive care unit (NICU).

METHODS

Urine samples of 135 infants who were admitted to the NICU during a 6 month period were evaluated to detect CMV using a nested PCR assay. A breast milk sample was obtained to determine viral excretion. Clinical characteristics of infected and non-infected infants were compared.

RESULTS

Congenital CMV infection was confirmed in two (1.48%) infants. Post-natal infection was documented in four of 36 (11.1%) infants that were evaluated. CMV excretion was detected in 43 of 116 mothers. Gestational age of infants born to mothers who excreted CMV was shorter than that of infants of mothers with negative results (33.1 versus 34.2 weeks; p = 0.07).

CONCLUSIONS

CMV excretion in breast milk is frequent and is associated to congenital and postnatal infection. Further studies are necessary to assess the impact of CMV infection during pregnancy and neonatal outcomes.

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.

Maternal human immunodeficiency virus infection and congenital transmission of cytomegalovirus

OBJECTIVES

To determine the frequency of congenital cytomegalovirus (CMV) infection in infants born to human immunodeficiency virus (HIV)-infected mothers and assess risk factors that may facilitate intrauterine transmission of CMV, including the role of perinatal HIV infection.

METHODS

Retrospective cohort study of infants who were born to HIV-infected mothers at Parkland Memorial Hospital and screened for congenital CMV infection according to a standard nursery protocol between February 1, 1997 and May 31, 2005.

RESULTS

During the 8-year study period that included 125,781 live births, there were 367 infants (0.3%) born to 303 HIV-infected mothers. Of 333 HIV-exposed infants who were screened for CMV, 10 (3%) had congenital CMV infection and 6 (60%) of these were identified only because of the CMV screening protocol. Four (1%) infants were infected with HIV, and none of these was CMV-infected. Compared with CMV-uninfected infants, CMV-infected, HIV-exposed newborns had lower mean birth weight (2508 versus 3148 g, P < 0.01), lower gestational age (37 vs. 39 weeks, P < 0.01), and higher median maternal HIV viral load at the start of prenatal care (15,411 vs. 2209 copies/mL, P = 0.02). CMV-infected infants were more likely to be born to mothers who were diagnosed with HIV during the pregnancy or at delivery (P = 0.03).

CONCLUSIONS

The prevalence of congenital CMV infection among HIV-exposed newborns was 3%. Screening of these infants for CMV would allow identification of infants who are at risk for delayed onset of hearing loss and other neurodevelopmental impairment.

Central nervous system disorders in infants with congenital cytomegalovirus infection

BACKGROUND

Congenital cytomegalovirus is the most common cause of congenital infection in developed countries and a major etiology for neurological disability in children. In many countries, there is low awareness of the importance of this virus as a cause of neurological disorders.

METHODS

We reviewed current knowledge regarding neurological disorders associated to congenital cytomegalovirus infection and analysed the epidemiology of this infection in Latin American countries.

RESULTS

The incidence of congenital cytomegalovirus infection reported from Latin American countries ranges from 0 to 6.8% in different settings. Congenital cytomegalovirus infection is a common cause of hearing deficits and mental impairment in children. However, the impact of this infection as a cause of neurological disorders in Latin American countries remains poorly documented.

DISCUSSION

Actions are needed to increase knowledge regarding the frequency and impact of congenital cytomegalovirus infection on Latin American children, as well as to increase awareness of the general population and the medical community regarding the need to identify infants infected in utero by this virus and to carefully evaluate their neurological development throughout childhood.

Influence of human cytomegalovirus infection on the NK cell receptor repertoire in children

Human cytomegalovirus (hCMV) infection is usually asymptomatic but may cause disease in immunocompromised hosts. It has been reported that hCMV infection may shape the NK cell receptor (NKR) repertoire in adult individuals, promoting a variable expansion of the CD94/NKG2C+ NK cell subset. We explored the possible relationship between this viral infection and the expression pattern of different NKR including CD94/NKG2C, CD94/NKG2A, immunoglobulin-like transcript 2 (ILT2, CD85j), KIR2DL1/2DS1, KIR3DL1, and CD161 in peripheral blood lymphocytes from healthy children, seropositive (n=21) and seronegative (n=20) for hCMV. Consistent with previous observations in adults, a positive serology for hCMV was associated with increased numbers of NKG2C+ NK and T cells as well as with ILT2+ T lymphocytes. Moreover, the proportions of CD161+ and NKG2C+CD56-CD3- NK cells also tended to be increased in hCMV+ individuals. Excretion of the virus was associated with higher proportions of NKG2C+ NK cells. Altogether, these data reveal that hCMV may have a profound influence on the NKR repertoire in early childhood.

Birth prevalence and natural history of congenital cytomegalovirus infection in a highly seroimmune population

BACKGROUND

The natural history of congenital cytomegalovirus (CMV) infection is scarcely known in populations with high maternal CMV seroprevalence. This study evaluated the birth prevalence, clinical findings at birth, and hearing outcome in CMV-infected children from such a population.

METHODS

Consecutively born infants were screened for the presence of CMV in urine and/or saliva specimens during the first 2 weeks after birth. Neonatal clinical findings were recorded, and CMV-infected children were tested to document hearing function during follow-up. A subset of mothers of CMV-infected infants were prenatally tested for the presence of anti-CMV immunoglobulin G antibodies.

RESULTS

Congenital CMV infection was confirmed in 87 (1.08%; 95% confidence interval [CI], 0.86%-1.33%) of 8047 infants. Seven infants (8.1%; 95% CI, 3.3%-15.9%) had at least 1 clinical finding suggestive of CMV infection, and 4 (4.6%; 95% CI, 1.3%-11.3%) had >3 findings of systemic disease. Sensorineural hearing loss was found in 5 (8.6%; 95% CI, 2.9%-19.0%) of 58 children tested at a median age of 21 months. Bilateral profound hearing loss was observed in 2 children, and the hearing threshold was >60 decibels in all 5 children with hearing loss, including 2 children born to mothers with probable nonprimary CMV infection.

CONCLUSIONS

The results of this large newborn screening study in a population with high CMV seroimmunity provide additional evidence that congenital CMV disease occurs in populations with high seroprevalence rates, with a similar incidence of CMV-related hearing loss to that reported in the offspring of women from populations in developed countries with lower rates of seroimmunity to CMV.

Newborn hearing screening and detection of congenital cytomegalovirus infection

OBJECTIVES

The objectives were to determine the frequency of congenital cytomegalovirus infection among newborns who did not pass hearing screening tests or had confirmed hearing loss and to determine how often abnormal hearing screening results were the only manifestation of congenital cytomegalovirus infection.

METHODS

Retrospective chart review was performed for newborns who had abnormal hearing screening results and positive urine cytomegalovirus culture results at Parkland Memorial Hospital between September 1, 1999, and August 31, 2004.

RESULTS

During the 5-year study period, 572 of 79047 newborns (7 of 1000 live births) did not pass hearing screening tests. Cytomegalovirus infection was identified in 24 (5%) of 483 tested infants and 16 (6%) of the 256 infants with subsequently confirmed hearing impairment. Of those 16 infants, 12 (75%) were identified as having congenital cytomegalovirus infection only because of failure to pass newborn hearing screening tests.

CONCLUSIONS

Congenital cytomegalovirus infection was present for 6% of newborns with confirmed hearing impairment, and the majority of those infants were identified on the basis of abnormal newborn hearing screening results.

Review and meta-analysis of the epidemiology of congenital cytomegalovirus (CMV) infection

We reviewed studies that reported results of systematic cytomegalovirus (CMV) screening on fetuses and/or live-born infants. The overall birth prevalence of congenital CMV infection was 0.64%, but varied considerably among different study populations. About 11% of live-born infants with congenital CMV infection were symptomatic, but the inter-study differences in definitions of symptomatic cases limit the interpretation of these data. Non-white race, low socioeconomic status (SES), premature birth, and neonatal intensive care unit admittance were risk factors for congenital CMV infection. Birth prevalence increased with maternal CMV seroprevalence. Maternal seroprevalence accounted for 29% of the variance in birth prevalence between study populations. Maternal seroprevalence and birth prevalence were both higher in study populations that were ascertained at birth rather than in the prenatal period. Thus, timing of ascertainment should be considered when interpreting birth prevalence estimates. Birth prevalence was inversely correlated with mean maternal age, but this relationship was not significant when controlling for maternal seroprevalence. The rate of transmission to infants born to mothers who had a primary infection or a recurrent infection during pregnancy was 32% and 1.4%, respectively. Possible maternal primary infections (i.e. seropositive mother with CMV IgM) resulted in congenital infections about 20% of the time, but are likely to represent a mixture of primary and recurrent infections. In summary, CMV is a common congenital infection worldwide that can lead to permanent disabilities. There is an urgent need for interventions that can reduce the substantial burden of this often overlooked disease.

Cytomegalovirus excretion in children attending day-care centers

BACKGROUND

Healthy children attending day-care centers (DCC) may excrete cytomegalovirus (CMV) frequently. Mothers of children excreting CMV are at higher risk for acquiring this infection than mothers of children not excreting CMV. Despite the increased attendance to DCC by children there is a lack of information regarding CMV infection in Mexico.

METHODS

Prospective determination of CMV excretion in saliva of children attending public and private DCC. Three saliva samples were collected during a 2-month follow-up period from participating children and the presence of CMV was determined by viral culture. Demographic features of children and DCC type were taken into account when comparing children with and without CMV excretion.

RESULTS

One hundred fifty-two children participated in the study (84 from public and 68 from private DCC). Overall, 17 (11.2%) children excreted CMV during the study period. Excretion rates varied between DCC from 3.1 to 31.3%. Children from private DCC were as likely to excrete CMV as children from public DCC. There were no demographic or clinical features of children associated with viral excretion.

CONCLUSIONS

CMV was excreted on an average of 11.2% children attending DCC. The type of DCC or other demographic features were not associated with the likelihood of CMV excretion. CMV seronegative mothers of children who attend DCC need to be aware of the possibility of CMV acquisition and transmission in DCC.