Congenital cytomegalovirus infection and neonatal auditory screening

Cytomegalovirus induces interferon-stimulated gene expression and is attenuated by interferon in the developing brain

Cytomegalovirus (CMV) is considered the most common infectious agent causing permanent neurological dysfunction in the developing brain. We have previously shown that CMV infects developing brain cells more easily than it infects mature brain cells and that this preference is independent of the host B- and T-cell responses. In the present study, we examined the innate antiviral defenses against mouse (m) and human (h) CMVs in developing and mature brain and brain cells. mCMV infection induced interferon (IFN)-stimulated gene expression by 10- to 100-fold in both glia- and neuron-enriched cultures. Treatment of primary brain cultures with IFN-alpha, -beta, and -gamma or a synthetic RNA, poly(I:C), reduced the number of mCMV-infected cells, both in older cells and in fresh cultures from embryonic mouse brains. When a viral dose that killed almost all unprotected cells was used, IFN-protected cells had a natural appearance, and when they were tested with whole-cell patch clamp recording, they appeared physiologically normal with typical resting membrane potentials and action potentials. mCMV infection increased expression of representative IFN-stimulated genes (IFIT3, OAS, LMP2, TGTP, and USP18) in both neonatal and adult brains to similarly large degrees. The robust upregulation of gene expression in the neonatal brain was associated with a much higher degree of viral replication at this stage of development. In contrast to the case for downstream gene induction, CMV upregulated IFN-alpha/beta expression to a greater degree in the adult brain than in the neonatal brain. Similar to the case with cultured brain cells, IFN treatment of the developing brain in vivo depressed mCMV replication. In parallel work with cultured primary human brain cells, IFN and poly(I:C) treatment reduced hCMV infection and prevented virus-mediated cell death. These results suggest that coupling IFN administration with current treatments may reduce CMV infections in the developing brain.

Nonhuman primate models of intrauterine cytomegalovirus infection

Congenital human cytomegalovirus (HCMV) infection has long been recognized as a threat to the developing fetus, even though studies have shown that only a subset of congenital infections results in clinical signs of disease. Among the estimated 8000 children who develop sequelae from congenital CMV infection each year in the United States alone, most suffer permanent developmental defects within the central nervous system. Because there is currently no approved vaccine for HCMV, and anti-HCMV drugs are not administered to gravid women with congenital infection because of potential toxicity to the fetus, there is a clear clinical need for effective strategies that minimize infection in the mother, transplacental transmission of the virus, and/or fetal disease. Animal models provide a method to understand the mechanisms of HCMV persistence and pathogenesis, and allow for testing of novel strategies that limit prenatal infection and disease. The rhesus macaque model is especially well suited for these tasks because monkeys and humans share strong developmental, immunological, anatomical, and biochemical similarities due to their close phylogenetic relationship. This nonhuman primate model provides an invaluable system to accelerate the clinical development of promising new therapies for the treatment of human disease. This review addresses salient findings with the macaque model as they relate to HCMV infection and potential avenues of discovery, including studies of intrauterine CMV infection. The complexity of the natural history of HCMV is discussed, along with the ethical and logistical issues associated with studies during pregnancy, the recent contributions of animal research in this field of study, and future prospects for increasing our understanding of immunity against HCMV disease.

Viral infections in the developing and mature brain

A number of different RNA and DNA viruses can invade the brain and cause neurological dysfunction. These range from the tiny polio picornavirus, which has only 7kb of RNA genetic code that preferentially infects motor neurons, to the relatively large cytomegalovirus, which has >100 genes in its 235kb DNA genome and causes various neurological problems in the developing brain but is comparatively harmless to adults. This brief overview of some aspects of neurovirology addresses the complex problems that underlie an appreciation of the contribution of viral infections to brain disease. [This review is part of the INMED/TINS special issue "Nature and nurture in brain development and neurological disorders", based on presentations at the annual INMED/TINS symposium (http://inmednet.com/).]

Congenital cytomegalovirus (CMV) infection and hearing deficit

BACKGROUND

The association between congenital cytomegalovirus (CMV) infection and sensorineural hearing loss (SNHL) was first described in 1964. Studies over the past four decades have further described the relationship between congenital CMV infection and SNHL in children.

OBJECTIVES

This manuscript will review the current knowledge of CMV-related SNHL and summarize the studies completed at the University of Alabama at Birmingham (UAB).

STUDY DESIGN

A review of the series of studies at UAB that has led to a more detailed characterization of hearing loss due to congenital CMV infection.

RESULTS

Approximately, 22%-65% of symptomatic and 6%-23% of asymptomatic children will have hearing loss following congenital CMV infection. CMV-related SNHL may be present at birth or occur later in childhood. Variability in the severity of CMV-related hearing loss ranges from unilateral high frequency losses to profound bilateral losses.

CONCLUSIONS

Congenital CMV infection significantly contributes to SNHL in many infant populations. Although, most children with congenital CMV infection do not develop hearing loss, it is difficult to predict which children with congenital CMV infection will develop hearing loss and, among those who do develop loss, whether or not the loss will continue to deteriorate.

Audiometric, clinical and educational outcomes in a pediatric symptomatic congenital cytomegalovirus (CMV) population with sensorineural hearing loss

OBJECTIVE

To correlate audiometric findings and outcomes with the clinical, radiological and educational findings in a symptomatic congenital cytomegalovirus (CMV) population with sensorineural hearing loss.

METHODS

A retrospective review of data from 21 symptomatic congenital CMV patients identified in a pediatric hearing impaired database of 1500 patients. Clinical data, audiometric thresholds and outcomes, radiographic abnormalities, communication and educational achievements were used as outcome measures.

RESULTS

Twenty-one patients were identified with symptomatic congenital CMV infection at birth; 5 with unilateral hearing loss and 16 with bilateral hearing loss. The median initial pure-tone average (PTA) for the 21 subjects was 86 dB and the median final PTA was 100 dB. Progression of hearing loss was seen in 9 patients (43%). Neurological and radiological sequelae of symptomatic CMV infection were seen in 81% of affected patients. Children with neurological dysfunction were significantly more likely to rely on special education (p = 0.045). There was a significant correlation between the severity of the initial PTA and the development of a progressive hearing loss (p = 0.0058). Initial hearing thresholds were significantly better in those children with a history of jaundice (p = 0.002), hepatosplenomegaly (HSM) (p = 0.022) and cerebral palsy (CP) (p = 0.013). There was a significant correlation between a less severe final PTA and the presence of CP (p = 0.005). A history of mental retardation in children was significantly associated with poorer communication skills (p = 0.043).

CONCLUSIONS

The severity of neurological manifestations in congenital symptomatic CMV infection was positively correlated with the need for total and manual communication and the reliance on special education. Statistical associations between clinical findings such as hepatic dysfunction, CP and hearing level were identified however plausible mechanisms explaining these associations remain ambiguous and are discussed in the context of this complex population of children with congenital symptomatic CMV.

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.

Herpesviridae infections in newborns: varicella zoster virus, herpes simplex virus, and cytomegalovirus

Varicella zoster virus (VZV), herpes simplex virus (HSV) and cytomegalovirus (CMV) are all members of the Herpesviridae family.Humans are the only source of infection for these double stranded DNA viruses. Infants may acquire these infections in utero, peripartum, or postnatally, resulting in a variety of clinical syndromes, ranging from asymptomatic infection to severe infection,with high mortality rates and significant long-term morbidity. This article presents the epidemiology, clinical characteristics, treatment,and prevention strategies for VZV, HSV, and CMV infections in infants.

Vaccine development to prevent cytomegalovirus disease: report from the National Vaccine Advisory Committee

Cytomegalovirus (CMV) infection is the most common intrauterine infection in the United States, and it exacts a heavy toll when it infects children and immunocompromised individuals. A CMV vaccine was assigned the highest priority by the Institute of Medicine in its 1999 assessment of targets for vaccine development. The priority was based on the cost and human suffering that would be alleviated by reducing the disease burden of congenital CMV infection. The National Vaccine Advisory Committee and invited experts examined the prospects for a CMV vaccine and the actions needed to bring about successful vaccine development at a National Vaccine Program Office workshop in October 2000. This article summarizes information about the changing epidemiology of CMV and immune responses to infection and immunity, and it reviews the current status of several vaccine candidates. Support of government agencies for CMV vaccine research and development is critical to address this need.

Routine CMV screening during pregnancy

Cytomegalovirus (CMV) screening during pregnancy has been widely discussed for several years, but still no consensus has been agreed. With a number of live births of 750,000 per year in France, we would expect 7500 infected infants at birth per year (rate of congenital infection of 1%). Among infected infants at birth, the number of severely infected foetuses would be approximately 75, the number of infants with severe sequelae would be 480, 675 approximately would present with hearing loss and the number of asymptomatic infants would be 6270. Five different preventive methods for congenital CMV infection are possible: (1) Routine CMV screening at the beginning of pregnancy for primary prevention. (2) Secondary prevention by antenatal diagnosis of congenital CMV infection complications. (3) Tertiary prevention by serological testing during pregnancy. (4) Tertiary prevention by serological screening at birth. (5) Tertiary prevention: Hearing loss screening at birth. The aims of this review are to define the advantages and disadvantages of these different methods of CMV screening during pregnancy and to determine if the current available information would make systematic testing acceptable.

Postnatally acquired cytomegalovirus infection via breast milk: effects on hearing and development in preterm infants

BACKGROUND

In preterm infants there is a high risk of transmission of cytomegalovirus (CMV) via breast milk from seropositive mothers with reactivation of the virus during lactation. There is little information about the long term sequel of early postnatally acquired CMV infection in pre-term infants. This study aimed to investigate whether there was an increased frequency of impaired neurodevelopmental outcome and sensorineural hearing loss in preterm infants with postnatally acquired CMV infection through transmission by CMV-positive breast milk.

METHODS

Twenty-two preterm infants [median birth weight, 1020 g (range, 600 to 1870 g); median gestational age, 27.6 weeks (range, 23.6 to 32 weeks] with early postnatally acquired CMV infection by breast-feeding (onset of viruria between Days 23 and 190 postnatally) were compared with 22 CMV-negative preterm infants individually matched for gestational age, birth weight, gender, intracranial hemorrhage and duration of ventilation. At 2 to 4.5 years of age, follow-up assessments were conducted consisting of neurologic examination, neurodevelopmental assessment and detailed audiologic tests.

RESULTS

None of the children had sensorineural hearing loss. There was no difference between the groups with regard to neurologic, speech and language or motor development.

CONCLUSION

The results of this study suggest that early postnatally acquired CMV infection via CMV-positive breast milk does not have a negative effect on neurodevelopment and hearing in this group of patients. Because we studied a small number of infants, further follow-up studies are warranted in preterm infants with early postnatally acquired CMV infection.

Enhanced cytomegalovirus infection of developing brain independent of the adaptive immune system

Cytomegalovirus (CMV) has been suggested as the most prevalent infectious agent causing neurological dysfunction in the developing brain; in contrast, CMV infections are rare in the adult brain. One explanation generally given for the developmental susceptibility to the virus is that the developing immune system is too immature to protect the central nervous system from viral infection, but as the immune system develops it can protect the brain. We suggest an alternate view: that developing brain cells are inherently more susceptible to CMV infection, independent of the immune system. We used a recombinant mouse CMV that leads to green fluorescent protein expression in infected cells. Control experiments demonstrated a high correlation between the number of cells detected with the viral GFP reporter gene and with immunocytochemical detection of the virus. After intracerebral inoculation, the number of CMV-infected cells in neonatal brains was many times greater than in mature control or mature immunodepressed SCID mice, and the mortality rate of neonates was substantially greater than SCID or control adults. Parallel experiments with live brain slices inoculated in vitro, done in the absence of the systemic immune system, generated similar data, with immature hippocampus, hypothalamus, cortex, striatum, and cerebellum showing substantially greater numbers of infected cells (100-fold) than found in adult slices in these same regions. Interestingly, in the cerebellar cortex, CMV-infected cells were more prevalent in the postmitotic Purkinje cell layer than in the mitotic granule cell layer, suggesting a selective infection of some cell types not dependent on cell division. Together, these data support the view that CMV has an intrinsic preference for infection of developing brain cells, independent, but not mutually exclusive, of the developmental status of the systemic immune system in controlling CMV infection.

Development of cytomegalovirus vaccines: prospects for prevention of congenital CMV infection

Congenital cytomegalovirus (CMV) infection is an important cause of hearing, cognitive, and motor impairments that cannot be effectively prevented or treated by any current medical or public health interventions. A review of priorities for vaccine development by The Institute of Medicine of the National Academy of Sciences concluded that a vaccine to prevent congenital CMV infection should be a top priority for the United States. Evidence from clinical studies indicates that immunity to CMV can reduce the frequency and severity of disease. Laboratory investigations have identified structural and nonstructural CMV proteins that play a key role in eliciting protective immunity. The rationale for development of a CMV vaccine has been strengthened further by studies in experimental animals demonstrating the ability of immunization with subunit vaccines to prevent disease and transplacental transmission of virus. At least 4 CMV vaccines are in clinical trials, and advances in biotechnology are paving the way for additional novel vaccines.

Mouse cytomegalovirus in developing brain tissue: analysis of 11 species with GFP-expressing recombinant virus

Cytomegaloviruses (CMVs) are species-specific large double-stranded DNA viruses. Mouse and human CMVs have a similar morphology, similar gene sequence, and exert similar cellular effects, but the replication of the virus outside its primary host species is limited. This may confer upon CMV certain advantages for expression of foreign genes or cellular labels in brain cells of nonhost species. We examined the ability of recombinant mouse (m)CMV expressing green fluorescent protein (GFP) to serve as a vector for transgene expression in developing neurons and glia outside the normal host species. For comparative purposes, 11 species were examined. Mouse CMV reporter gene expression was particularly strong in the developing brain of its normal host species, mouse, where it replicated in cultures and brain slices, leading to cell death. All mammalian species tested (human, rat, gerbil, hamster, mouse) showed reporter gene expression after mCMV infection. High levels of mCMV infection were also found in chicken central nervous system cells in vitro, and a low level of mCMV expression was found after an initial delay in turtle neurons and glia. No mCMV reporter gene expression was found in frog cells or aplysia neurons or glia or in drosophila or fungal cells. Infection of nonmouse neurons by low concentrations of mCMV led to strong expression of GFP in dendrites and axons with normal morphology. Despite the lack of replication, high doses of mCMV induced morphologic changes in neurons and glia from hamster and rat brain slices, leading to cells rounding up, and to the formation of giant cells consisting of an aggregate of many cells fused together into a syncytium. In contrast, in human hippocampal slices, GFP-expressing cells infected with mCMV had a relatively normal appearance 12 days after inoculation. To determine whether a CMV from another species could serve as a vector for gene transfer, a recombinant human CMV-expressing GFP was used for transgene expression in rat brain cells in vitro. Cytomegaloviruses thus have potential as useful vectors for gene transfer and labeling central nervous system cells, with the actions of CMV being dependent on a number of factors.

Identification of neonatal hearing impairment: characteristics of infants in the neonatal intensive care unit and well-baby nursery

OBJECTIVE

The objective of this study was to describe the demographic data, medical status, and incidence of risk factors for hearing impairment in the neonatal intensive care unit (NICU) and well-baby populations in a multicenter prospective study designed to assess neonatal hearing impairment and to evaluate factors that might affect neonatal hearing test performance.

DESIGN

This was a prospective multicenter study funded by the National Institutes of Health-National Institute on Deafness and Other Communication Disorders to evaluate the effectiveness of auditory brain stem response, transient evoked otoacoustic emissions, and distortion product otoacoustic emissions for newborn hearing screening. Research staff at each site obtained informed consent and detailed demographic and medical data, including information on established risk factors for hearing loss on 4478 high-risk infants cared for in the NICU, 2348 infants from the well-baby nurseries with no risk factor, and 353 infants from the well-baby nurseries with risk factors. For follow-up purposes the sample was divided further to include a subgroup called selects. Selects were either infants from the well-baby nursery who had an established risk factor for hearing impairment (N = 353) or did not pass the neonatal hearing screen protocol (N = 80). In this study, we focus on the distribution of infants by nursery and risk factors only. Particular effort was made to enroll infants with risk factors for hearing loss in both the NICU and well-baby nurseries. Descriptive analyses are used to describe characteristics of this sample.

RESULTS

All 10 of the risk factors established by the Joint Committee on Infant Hearing in 1994 were identified in the NICU population. The four most common were ototoxic medications (44.4%), very low birth weight (17.8%), assisted ventilation > 5 days (16.4%), and low Apgar scores at 1 or 5 min (13.9%). In contrast, only six risk factors were present in the well-baby nurseries: family history (6.6%), craniofacial abnormalities (3.4%), low Apgar scores (2.8%), syndromes (0.5%), ototoxic medications (0.2%), and congenital infection (0.1%).

CONCLUSION

These descriptive risk factor data reflect both the newborn populations at the study sites and the bias for enrolling infants at risk for hearing loss. The high-risk NICU sample reflects the characteristics typically found in graduates of the NICU. The data summarized in this study will be used to assess the relationships between risk factor and hearing test outcome.

Cytomegalovirus cell tropism, replication, and gene transfer in brain

Cytomegalovirus (CMV) infects a majority of adult humans. During early development and in the immunocompromised adult, CMV causes neurological deficits. We used recombinant murine cytomegalovirus (mCMV) expressing either green fluorescent protein (GFP) or beta-galactosidase under control of human elongation factor 1 promoter or CMV immediate early-1 promoter as reporter genes for infected brain cells. In vivo and in vitro studies revealed that neurons and glial cells supported strong reporter gene expression after CMV exposure. Brain cultures selectively enriched in either glia or neurons supported viral replication, leading to process degeneration and cell death within 2 d of viral exposure. In addition, endothelial cells, tanycytes, radial glia, ependymal cells, microglia, and cells from the meninges and choroid were infected. Although mCMV showed no absolute brain cell preference, relative cell preferences were detected. Radial glia cells play an important role in guiding migrating neurons; these were viral targets in the developing brain, suggesting that cortical problems including microgyria that are a consequence of CMV may be caused by compromised radial glia. Although CMV is a species-specific virus, recombinant mCMV entered and expressed reporter genes in both rat and human brain cells, suggesting that mCMV might serve as a vector for gene transfer into brain cells of non-murine species. GFP expression was sufficiently strong that long axons, dendrites, and their associated spines were readily detected in both living and fixed tissue, indicating that mCMV reporter gene constructs may be useful for labeling neurons and their pathways.

Report on a long-term study of maternal and congenital cytomegalovirus infection in Sweden. Review of prospective studies available in the literature

This report summarizes knowledge accumulated in a long-term study of congenital and maternal cytomegalovirus (CMV) infection in Sweden. Some new findings are included. We considered diagnostic methods, sources of maternal infection (including occupational risks), roles of primary and secondary maternal infections, transmission to foetuses, incidence, symptoms and prognosis of established congenital infection and relative importance of such infection in infantile sensorineural deafness, microcephaly and type 1 diabetes mellitus. Virus isolation testing was done 1977-1985 on 16,474 newborns. 76 (0.5%) congenitally infected infants were found, 22/76 (29%) with transient neonatal symptoms and 11/60 (18%) with neurological symptoms by the age of 7 y. Type of maternal CMV infection was serologically determined in 62/76 cases (30 primary, 32 secondary). CNS disturbances in the infants occurred after both primary (all trimesters) and secondary maternal infections. The negative potential of secondary maternal infections might be an obstacle to preventive vaccination.

Newborn hearing screening: will children with hearing loss caused by congenital cytomegalovirus infection be missed?

OBJECTIVE

To predict whether universal newborn auditory screening will identify most infants with sensorineural hearing loss (SNHL) caused by congenital cytomegalovirus (CMV) infection.

STUDY DESIGN

A cohort of 388 children born between 1980 and 1996 at one hospital and identified during the newborn period as having congenital CMV infection received repeated hearing evaluations to assess whether hearing loss had occurred.

RESULTS

SNHL was detected in 5.2% of all infants at birth. Late-onset SNHL occurred among the children throughout the first 6 years of life. By the age of 72 months, the cumulative incidence of SNHL was 15.4% in the cohort. Children with clinically apparent disease at birth had significantly more SNHL than children without any apparent disease (22.8% vs 4.0% at 3 months and 36.4% vs 11.3% at 72 months of age).

CONCLUSIONS

Universal screening of hearing in neonates will detect less than half of all SNHL caused by congenital CMV infection. Because most infants with congenital CMV infection are without symptoms at birth, these children are unlikely to be recognized as being at risk for SNHL and will not receive further hearing evaluations to detect late-onset hearing loss. A combined approach of universal screening of neonates for hearing, as well as for detection of congenital CMV infection, needs to be considered.

Progressive and fluctuating sensorineural hearing loss in children with asymptomatic congenital cytomegalovirus infection

OBJECTIVE

To determine the prevalence and temporal changes of sensorineural hearing loss (SNHL) among children with clinically inapparent (asymptomatic) congenital cytomegalovirus (CMV) infection identified from a cohort of newborn infants screened for congenital CMV infection.

METHODS

The study population consisted of 307 children with documented asymptomatic congenital CMV infection, 76 uninfected siblings of children with asymptomatic congenital CMV infection, and 201 children whose neonatal screen for congenital CMV infection showed negative results. Audiologic evaluations were completed for all children to determine their hearing status.

RESULTS

SNHL occurred only in children with congenital CMV infection. Of the children with asymptomatic congenital CMV infection, 22 (7.2%; 95% confidence interval, 4.5% to 10.6%) had SNHL. Among the children with hearing loss, further deterioration of hearing occurred in 50.0%, with the median age at first progression at 18 months (range, 2 to 70 months). Delayed-onset SNHL was observed in 18.2% of the children, with the median age of detection at 27 months (range, 25 to 62 months). Fluctuating SNHL was documented in 22.7% of the children with hearing loss.

CONCLUSIONS

Asymptomatic congenital CMV infection is likely a leading cause of SNHL in young children. The continued deterioration of hearing and delayed onset of SNHL in these children emphasizes the need for continued monitoring of their hearing status.

Audiovestibular sequelae of congenital cytomegalovirus infection in 3 children presumably representing 3 symptomatically different types of delayed endolymphatic hydrops

Three cases of congenital cytomegalovirus (CMV) infection with long-term audiovestibular sequelae are presented. Case 1 had no hearing in one ear and severe progressive hearing loss in the other ear; he showed vestibular symptoms at the age of 4.5 years. Case 2 had severe but stationary hearing loss in one ear and showed hearing impairment symptoms in the other ear at 9-13 years of age. Case 3 did not have hearing impairment symptoms, or vestibular symptoms, but was found to have severe progressive hearing loss from the age of 15 months onwards, which led to profound deafness at the age of 2 years and vestibular areflexia at or before the age of 4 years. These cases may represent 3 symptomatically different types of delayed endolabyrinthine hydrops. Type 1 (ipsilateral hydrops) incorporates vestibular symptoms only because of a lack of hearing in the offending labyrinth. Type 2 (contralateral hydrops) incorporates hearing impairment symptoms only because of a lack of vestibular function on both sides and type 3 does not incorporate hearing impairment symptoms or vestibular symptoms (other than those relating to a complete lack of function). Given the present findings, those described by Weiss and Ronis (Trans. Pa. Acad. Opthalmol. Otolaryngol., 30 (1977) 52-54) in one case and other reported findings relating to histopathological or imaging methods in somewhat similar cases, it seems appropriate to include congenital CMV infection in the differential diagnosis of delayed endolymphatic hydrops.

Infection materno-foetale à cytomégalovirus

Congenital cytomegalovirus infection is frequent. Symptomatic disease at birth is infrequent but very severe. In most cases the infection is totally asymptomatic but neurosensorial damage can occur in 10 % to 15 % of children, hearing loss being the most frequent. Maternal or neonatal screening is the only way to recognise asymptomatic disease. Wether the screening has to be done, and if so when, will be discussed here.

Screening for congenital cytomegalovirus infection among preterm infants born before the 34th gestational week in Finland

83 infants born before 34 weeks of gestation between 1989 and 1990 and cared for at a neonatal intensive care unit in Kuopio, Finland, were screened for congenital cytomegalovirus (CMV) infection, defined as a positive culture from the sample of urine taken on the first day after birth. Four infants were infected and excreted CMV in the urine. The overall incidence of CMV excretors was 4.8%. The incidence was 1/13 infants born before 28 weeks' gestation and 3/70 infants born between 28 and 34 weeks of gestation. The 4 CMV excretors were followed up for 12-25 months. Two children had normal psychomotor and mental development but exhibited decreasing head growth during follow-up. The other 2 developed severe psychomotor retardation, retinopathy of prematurity, chorioretinitis, and microcephaly. The long-term morbidity was associated not only with congenital CMV infection but to prematurity as well. The incidence of congenital CMV excretors in this preterm population seemed to be higher than reported previously among unselected live-born infants. Early diagnosis of congenital CMV infection would seem to be important in view of forthcoming new therapeutic regimes in the near future.