Diagnosis of congenital cytomegalovirus infection by detection of viral DNA in dried blood spots

Diagnosing congenital cytomegalovirus infections using archived dried blood spots: A 15-year observational study, Portugal

BACKGROUND

Cytomegalovirus (CMV) is a leading cause of congenital infections. Dried blood spots (DBS) collected in the first week of life (Guthrie cards) have been used in the diagnosis of CMV infection outside the three-week window period following birth. The present work summarizes the results of a 15-year observational study in which DBS from 1388 children were used for a late diagnosis of congenital CMV infection.

METHODS

Three groups of children were studied: (i) symptomatic (with symptoms at birth or late sequelae) (N = 779); (ii) born to mothers with serological profile of primary CMV infection (N = 75); (iii) without any information (N = 534). A highly sensitive method of DNA extraction (heat-induced) from the DBS was used. CMV DNA was detected by a nested PCR.

RESULTS

In total CMV DNA was detected in 7.5% (104/1388) of children. Symptomatic children showed a low rate of CMV DNA detection (6.7%) than children born to mothers with serological profile of primary CMV infection (13.3%) (p = 0.034). Sensorial hearing loss and encephalopathy were the two clinical manifestations with the highest CMV detection rate (18.3% and 11.1%, respectively). Children whose mothers had a confirmed primary infection showed a higher rate of CMV detection (35.3%) when compared with children whose mothers had a not confirmed primary infection (6.9%) (p = 0.007).

CONCLUSION

The present work emphasises the importance of testing DBS in symptomatic children even a long time after symptoms onset and in children born to mothers with serologic diagnosis of maternal primary CMV infection when they miss the diagnosis during the three-week window following birth.

Loss to follow up of failed hearing screen and missed opportunities to detect congenital cytomegalovirus are better identified with the implementation of a new electronic health record system protocol

INTRODUCTION

Congenital CMV (cCMV) is the leading cause of non-genetic sensorineural hearing loss. Babies with cCMV can present with hearing loss any time but failing the initial hearing screen should trigger cCMV testing. cCMV must be identified within 3 weeks after birth to differentiate congenital from acquired CMV, yet follow-up hearing screens may not occur until after 21 days. A new electronic health record protocol to test cCMV in babies who fail their initial hearing screen was established at our institution in 2013. The purpose of this study is to evaluate adherence and deviations from this protocol.

METHODS

All term infants born in 2013-2016 who failed initial hearing screen were included. The records were reviewed retrospectively. Demographic data, dates of hearing screens, CMV testing results and follow-up hearing test results were collected.

RESULTS

A total of 19,069 newborn babies were screened between 2013 and 2016. Babies who were in the neonatal intensive care unit whether premature or not were excluded as these infants are often in the hospital longer than 3 weeks so audiologic diagnostic testing may be delayed. Among term newborns screened, 1358 failed initial screen and 444 failed subsequent hearing testing prior to discharge. We identified 60 babies who did not follow up and 59 underwent additional audiologic testing. Overall 38 babies were tested for cCMV with 2 positives. We found an increase in cCMV testing over time and a significant decrease between physical distance from birth hospital and outpatient audiologic follow-up testing within 21 days of birth.

DISCUSSION

Our results are consistent with a 0.4% rate of cCMV in full-term babies who failed their newborn hearing screen. From 2013 to 2016, more babies received CMV tests, but post-screening follow up was still delayed. Further research is necessary to address factors affecting follow up. Use of electronic health record eased identification of results and improved tracking.

Congenital Human Cytomegalovirus Infection: A Narrative Review of Maternal Immune Response and Diagnosis in View of the Development of a Vaccine and Prevention of Primary and Non-Primary Infections in Pregnancy

Congenital cytomegalovirus infection (cCMV) may affect about 1% of all newborns all over the world as a result of either a primary or recurrent human cytomegalovirus (HCMV) infection. While about 90% of infants affected by cCMV are asymptomatic at birth, the remaining 10% are symptomatic often with neurodevelopmental impairment and sensorineural hearing loss. In view of identifying the best approach to vaccine prevention of cCMV, this review will examine the most important steps made in the study of the immune response to, and diagnosis of, HCMV infection. The maternal immune response and immune correlates of protection are being partially identified with a partial contribution given by our laboratory. The diagnosis of primary infection is often difficult to achieve in the first three months of pregnancy, which is the time primarily involved in virus transmission to the fetus in association with the most severe symptoms and sequelae. Prevention of cCMV is anticipated by prevention of primary infection in early pregnancy by means of different measures, such as (i) behavioral-educational measures, (ii) immunoglobulin administration, (iii) antiviral treatment with valaciclovir. However, the most promising approach to cCMV prevention appears to be the development of a non-living vaccine, including at least three viral antigens: gB, pentamer complex gHgLpUL128L, and pp65, which have been shown to be able to stimulate both the humoral and the cellular arms of the maternal immune response. Primary HCMV infection may be managed in pregnancy by counseling of the couples involved by a team of specialists that includes virologists, obstetricians, infectivologists and neonatologists.

Clinical Diagnostic Testing for Human Cytomegalovirus Infections

Human cytomegalovirus (HCMV) infections are among the most common complications arising in transplant patients, elevating the risk of various complications including loss of graft and death. HCMV infections are also responsible for more congenital infections worldwide than any other agent. Congenital HCMV (cCMV) infections are the leading nongenetic cause of sensorineural hearing loss and a source of significant neurological disabilities in children. While there is overlap in the clinical and laboratory approaches to diagnosis of HCMV infections in these settings, the management, follow-up, treatment, and diagnostic strategies differ considerably. As yet, no country has implemented a universal screening program for cCMV. Here, we summarize the issues, limitations, and application of diagnostic strategies for transplant recipients and congenital infection, including examples of screening programs for congenital HCMV that have been implemented at several centers in Japan, Italy, and the United States.

Congenital Cytomegalovirus Infection: Update on Diagnosis and Treatment

Congenital cytomegalovirus (cCMV) infection is the most common congenital viral infection and is the leading non-genetic cause of sensorineural hearing loss (SNLH) and an important cause of neurodevelopmental disabilities. The risk of intrauterine transmission is highest when primary infection occurs during pregnancy, with a higher rate of vertical transmission in mothers with older gestational age at infection, while the risk of adverse fetal effects significantly increases if fetal infection occurs during the first half of pregnancy. Despite its prevalence and morbidity among the neonatal population, there is not yet a standardized diagnostic test and therapeutic approach for cCMV infection. This narrative review aims to explore the latest developments in the diagnosis and treatment of cCMV infection. Literature analysis shows that preventive interventions other than behavioral measures during pregnancy are still lacking, although many clinical trials are currently ongoing to formulate a vaccination for women before pregnancy. Currently, we recommend using a PCR assay in blood, urine, and saliva in neonates with suspected cCMV infection. At present, there is no evidence of the benefit of antiviral therapy in asymptomatic infants. In the case of symptomatic cCMV, we actually recommend treatment with oral valganciclovir for a duration of 12 months. The effectiveness and tolerability of this therapy option have proven effective for hearing and neurodevelopmental long-term outcomes. Valganciclovir is reserved for congenitally-infected neonates with the symptomatic disease at birth, such as microcephaly, intracranial calcifications, abnormal cerebrospinal fluid index, chorioretinitis, or sensorineural hearing loss. Treatment with antiviral drugs is not routinely recommended for neonates with the mildly symptomatic disease at birth, for neonates under 32 weeks of gestational age, or for infants more than 30 days old because of insufficient evidence from studies. However, since these populations represent the vast majority of neonates and infants with cCMV infection and they are at risk of developing late-onset sequelae, a biomarker able to predict long-term sequelae should also be found to justify starting treatment and reducing the burden of CMV-related complications.

A newborn screening pilot study using methylation-sensitive high resolution melting on dried blood spots to detect Prader-Willi and Angelman syndromes

Prader-Willi (PWS) and Angelman (AS) syndromes are two clinically distinct imprinted disorders characterized by genetic abnormalities at 15q11-q13. Early diagnosis of both syndromes provides improved treatment and accurate genetic counseling. Whole blood (WB) is the most common DNA source of many methodologies to detect PWS and AS, however, the need of WB makes a massive screening difficult in newborns due to economic and technical limitations. The aim of this study was to adapt a Methylation-sensitive High-Resolution Melting (MS-HRM) approach from dried blood spot (DBS) samples, assessing the different DNA isolation techniques and diagnostic performance. Over a 1-year period, we collected 125 DBS cards, of which 45 had already been diagnosed by MS-HRM (20 PWS, 1 AS, and 24 healthy individuals). We tested three different DBS-DNA extraction techniques assessing the DNA concentration and quality, followed by MS-HRM and statistical comparison. Each DBS-DNA extraction method was capable of accuracy in detecting all PWS and AS individuals. However, the efficiency to detect healthy individuals varied according to methodology. In our experience, DNA extracted from DBS analyzed by the MS-HRM methodology provides an accurate approach for genetic screening of imprinting related disorders in newborns, offering several benefits compared to traditional whole blood methods.

Should hearing targeted screening for congenital cytomegalovirus infection Be implemented?

Since 2013, after Utah became the first state to implement hearing targeted early CMV screening, a national debate has been percolating about whether this approach should be introduced nationally. Currently Utah, Iowa, Connecticut, and New York have passed legislation mandating early CMV screening, and over 100 birth hospitals across the United States have voluntarily implemented early CMV screening programs as part of their standard of care. We reviewed the evidence related to this approach and used the Wilson and Jungner (1968) criteria to evaluate this method of screening. Based on these criteria, there is substantial rationale and evidence to support a hearing targeted approach to screen for congenital CMV. Given this evidence, we currently recommend that infants who fail newborn hearing screen should undergo CMV screening.

Development of highly efficient protocols for extraction and amplification of cytomegalovirus DNA from dried blood spots for detection and genotyping of polymorphic immunomodulatory genes

Congenital cytomegalovirus (CMV) infection is a major cause of birth defects ranging from developmental disorders to stillbirth. Most newborns affected by CMV do not present with symptoms at birth but are at risk of sequelae at later stages of their childhood. Stored dried blood spots (DBS) taken at birth can be used for retrospective diagnosis of hereditary diseases, but detection of pathogens is challenged by potentially low pathogen concentrations in the small blood volume available in a DBS. Here we test four different extraction methods for optimal recovery of CMV DNA from DBS at low to high CMV titers. The recovery efficiencies varied widely between the different extractions (from 3% to 100%) with the most efficient method extracting up to 113-fold more CMV DNA than the least efficient and 8-fold more than the reference protocol. Furthermore, we amplified four immunomodulatory CMV genes from the extracted DNA: the UL40 and UL111A genes which occur as functional knockouts in some circulating CMV strains, and the highly variable UL146 and US28 genes. The PCRs specifically amplified the CMV genes at all tested titers with sufficient quality for sequencing and genotyping. In summary, we here report an extraction method for optimal recovery of CMV DNA from DBSs that can be used for both detection of CMV and for genotyping of polymorphic CMV genes in congenital CMV infection.

Congenital Cytomegalovirus Infection in Children with Autism Spectrum Disorder: Systematic Review and Meta-Analysis

Association of congenital cytomegalovirus (CMV) infection with autism spectral disorder (ASD) has been suggested since 1980s. Despite the observed association, its role as a risk factor for ASD remains to be defined. In the present review, we systematically evaluated the available evidence associating congenital CMV infection with ASD using PubMed, Web of Science, Cochrane Library, and Embase databases. Any studies on children with CMV infection and ASD were evaluated for eligibility and three observational studies were included in meta-analysis. Although a high prevalence of congenital CMV infection in ASD cases (OR 11.31, 95% CI 3.07-41.66) was indicated, too few events (0-2 events) in all included studies imposed serious limitations. There is urgent need for further studies to clarify this issue.

Evaluation of rapid and sensitive DNA extraction methods for detection of cytomegalovirus in dried blood spots

BACKGROUND

Dried blood spots (DBS), collected universally from newborns in the U.S., could be used as a matrix for the detection of cytomegalovirus (CMV) infection in infants. However, sensitivity to detect CMV in DBS as compared to saliva and urine is variable across studies largely due to the DNA extraction method. Thermal shock, a widely used DNA extraction method, is highly sensitive for the detection of CMV in DBS, however, the processing time required is not practical for high-throughput testing.

OBJECTIVE

To determine if rapid and cost-effective DNA extraction methods amenable to newborn screening (NBS) could achieve the same sensitivity as the thermal shock method.

STUDY DESIGN

DBS were prepared from CMV positive blood samples from 20 organ transplant recipients. Three DNA extraction methods were compared for relative yield and sensitivity of detection of CMV DNA: thermal shock, KOH Tris buffer, and DNA Extract All. CMV DNA was detected by real-time quantitative polymerase chain reaction (qPCR).

RESULTS

The KOH Tris and DNA Extract All methods gave higher yields and sensitivity of CMV detection in DBS than thermal shock, which were significantly greater when viral loads were ≤ 10,000 copies/ml blood. Both methods gave faster turnaround times than thermal shock and would be better suited for NBS.

CONCLUSIONS

The choice of DNA extraction method greatly influences the ability to detect low levels of CMV DNA in DBS. Moreover, development of highly sensitive yet rapid methods for CMV detection could help facilitate future newborn screening of CMV in DBS.

[A 15-year-old girl with congenital cytomegalovirus infection presenting with sensorineural hearing impairment and cerebral while matter lesions but no intellectual disability]

A 15-year-old girl presented with non-progressive sensorineural hearing impairment in her right ear since her early childhood. She had normal intellectual development. When she was 15 years old, small deep white matter lesions around the lateral ventricles were incidentally detected in brain MRI studies through further investigation of auditory organs. Laboratory data including cerebrospinal fluid analysis and antibodies to aquaporin-4 or myelin-oligodendrocyte glycoprotein were normal. She was diagnosed as a congenital cytomegalovirus (CMV) infection based on the detection of CMV DNA from preserved umbilical cord tissue by real-time polymerase chain reaction. It should be kept in mind that a case of congenital CMV infection with normal intelligence may be underdiagnosed and that sensorineural hearing impairment from early childhood and deep white matter abnormalities can be key features giving rise to suspicion on congenital CMV infection.

Prevalence of Congenital Cytomegalovirus Infection Assessed Through Viral Genome Detection in Dried Blood Spots in Children with Autism Spectrum Disorders

BACKGROUND/AIM

Autism spectrum disorders (ASD) are neurodevelopmental disorders without a definitive etiology in most cases. Environmental factors, such as viral infections, have been linked with anomalies in brain growth, neuronal development, and functional connectivity. Congenital cytomegalovirus (CMV) infection has been associated with the onset of ASD in several case reports. The aim of this study was to evaluate the prevalence of congenital CMV infection in children with ASD and in healthy controls.

PATIENTS AND METHODS

The CMV genome was tested by polymerase chain reaction (PCR) on dried blood spots collected at birth from 82 children (38 with ASD and 44 controls).

RESULTS

The prevalence of congenital CMV infection was 5.3% (2/38) in cases and 0% (0/44) in controls (p=0.212).

CONCLUSION

The infection rate was about 10-fold higher in patients with ASD than in the general Italian population at birth. For this reason, detection of CMV-DNA on dried blood spots could be considered in the work-up that is usually performed at ASD diagnosis to rule-out a secondary form. Given the potential prevention and treatment of CMV infection, this study could have intriguing consequences, at least for a group of patients with ASD.

Evaluation and management of cytomegalovirus-associated congenital hearing loss

PURPOSE OF REVIEW

The current article reviews the current literature related to congenital cytomegalovirus (CMV)-related hearing loss. The discussion will focus on the epidemiology, pathogenesis, and clinical presentation of human CMV infection as it pertains to hearing loss. Current methods of CMV diagnosis with a focus on the evolving trend toward broader neonatal screening protocols will also be explored. Discussion of medical, surgical, and audiologic management of the condition will also be addressed.

RECENT FINDINGS

Much of the current research on this topic is focused on improving detection of CMV through screening programs. Some advances in understanding cochlear pathogenesis have also been made.

SUMMARY

Congenital CMV infection remains an important cause of hearing loss in infants and children. Early detection of CMV infection can broaden treatment options and allow for improved hearing and language outcome for patients with CMV-associated sensorineural hearing loss.

Analysis of archived newborn dried blood spots (DBS) identifies congenital cytomegalovirus as a major cause of unexplained pediatric sensorineural hearing loss

PURPOSE

Congenital cytomegalovirus (cCMV) infection is the most common non-genetic cause of sensorineural hearing loss (SNHL). However, accurate diagnosis of cCMV as the etiology of SNHL is problematic beyond the neonatal period. This study therefore examined whether cCMV infection could be identified retrospectively in children presenting with unexplained SNHL to a multidisciplinary diagnostic outpatient otolaryngology clinic at an academic medical center in Minnesota.

METHODS

Over a 4-year period, 57 patients with an age range of 3months to 10years with unexplained SNHL were recruited to participate in this study. Informed consent was obtained to test the archived dried blood spots (DBS) of these patients for cCMV infection by real-time PCR, targeting a highly conserved region of the CMV UL83 gene. Results were normalized to recovery of an NRAS gene control. Chart review was conducted to identify subjects who underwent genetic testing and/or neurodiagnostic imaging to investigate possible genetic, syndromic, or anatomical causes of SNHL.

RESULTS

In total, 15 of the 57 children with unexplained SNHL tested positive for CMV DNA in their DBS (26%). A mean viral load of 8.3×10⁴ (±4.1×10⁴) [range, 1×10³-6×10⁵] copies/μg DNA was observed in subjects retrospectively diagnosed with cCMV. No statistically significant correlation was found between viral load and SNHL severity.

CONCLUSIONS

A retrospective DBS analysis demonstrated that 26% of patients presenting with unexplained SNHL in childhood had cCMV. DBS testing is useful in the retrospective diagnosis of cCMV, and may provide definitive diagnostic information about the etiology of SNHL.

No evidence of congenital varicella zoster virus infection assessed through dried blood spot in children with autism spectrum disorders

Aim: Several authors have hypothesized an association between congenital viral infections and the onset of autism spectrum disorders (ASD). We aimed to assess the prevalence of congenital varicella zoster virus (VZV) infection in patients with ASD. Patients & methods: Congenital infection by VZV was evaluated in a cohort of 38 children with ASD and in 44 healthy controls. PCR for VZV-DNA performed on dried blood spots collected at birth. Results & conclusion: No VZV infection was detected in both groups. With the limitation of the small sample size of this study, the results are not in favor of a role of VZV in the etiology of ASD.

Newborn Dried Blood Spot Polymerase Chain Reaction to Identify Infants with Congenital Cytomegalovirus-Associated Sensorineural Hearing Loss

OBJECTIVE

To determine the utility of dried blood spot (DBS) polymerase chain reaction (PCR) in identifying infants with cytomegalovirus (CMV) infection-associated sensorineural hearing loss (SNHL).

STUDY DESIGN

Newborns at 7 US hospitals between March 2007 and March 2012 were screened for CMV by saliva rapid culture and/or PCR. Infected infants were monitored for SNHL during the first 4 years of life to determine sensitivity, specificity, and positive and negative likelihood ratios of DBS PCR for identifying CMV-associated SNHL.

RESULTS

DBS at birth was positive in 11 of 26 children (42%) with SNHL at age 4 years and in 72 of 270 children (27%) with normal hearing (P = .11). The sensitivity (42.3%; 95% CI, 23.4%-63.1%) and specificity (73.3%; 95% CI, 67.6%-78.5%) was low for DBS PCR in identifying children with SNHL at age 4 years. The positive and negative likelihood ratios of DBS PCR positivity to detect CMV-associated SNHL at age 4 years were 1.6 (95% CI, 0.97-2.6) and 0.8 (95% CI, 0.6-1.1), respectively. There was no difference in DBS viral loads between children with SNHL and those without SNHL.

CONCLUSIONS

DBS PCR for CMV has low sensitivity and specificity for identifying infants with CMV-associated hearing loss. These findings, together with previous reports, demonstrate that DBS PCR does not identify either the majority of CMV-infected newborns or those with CMV-associated SNHL early in life.

Congenital Cytomegalovirus infection: advances and challenges in diagnosis, prevention and treatment

Cytomegalovirus (CMV) is the most frequent cause of congenital infection worldwide, with an estimated incidence in developing countries of 0.6-0.7% of all live births. The burden of disease related to congenital CMV in substantial, as it is the leading non-genetic cause of sensorineural hearing loss and an important cause of neurodevelopmental disabilities in children. Despite its clinical significance, congenital CMV infection often goes undetected because the majority of infected infants are asymptomatic at birth and screening programs have not been substantially implemented. Other than behavioral measures, effective interventions aimed at the prevention of maternal infection and of mother-to-child transmission are lacking. Due to a convergence of recent advances in both diagnostic and therapeutic strategies in infants with congenital CMV, though, the field likely will be changing rapidly over just the next few years. Specifically, a highly-sensitive screening test with high throughput potential has been developed, and treatment of infants symptomatically infected with congenital CMV has proven to be well-tolerated and effective in improving long-term hearing and neurodevelopmental outcomes.This review highlights the clinical importance of congenital CMV infection, the developments in laboratory diagnostics, and the benefits of antiviral therapy. It also identifies the global efforts still required in the prevention of maternal infection and in the optimization of antiviral therapy to further reduce the burden of congenital CMV disease.

Evaluation of DNA extraction methods for the detection of Cytomegalovirus in dried blood spots

BACKGROUND

Dried blood spots (DBS) are collected universally from newborns and may be valuable for the diagnosis of congenital Cytomegalovirus (CMV) infection. The reported analytical sensitivity for DBS testing compared to urine or saliva varies greatly across CMV studies. The purpose of this study was to directly compare the performance of various DNA extraction methods for identification of CMV in DBS including those used most often in CMV studies.

STUDY DESIGN

Whatman(®) Grade 903 filter paper cards were spotted with blood samples from 25 organ transplant recipients who had confirmed CMV viremia. Six DNA extraction methods were compared for relative yield of viral and cellular DNA: 2 manual solution-based methods (Gentra Puregene, thermal shock), 2 manual silica column-based methods (QIAamp DNA Mini, QIAamp DNA Investigator), and 2 automated methods (M48 MagAttract Mini, QIAcube Investigator). DBS extractions were performed in triplicate followed by real-time quantitative PCR (qPCR).

RESULTS

For extraction of both viral and cellular DNA, two methods (QIAamp DNA Investigator and thermal shock) consistently gave the highest yields, and two methods (M48 MagAttract Mini and QIAamp DNA Mini) consistently gave the lowest yields. There was an average 3-fold difference in DNA yield between the highest and lowest yield methods.

CONCLUSION

The choice of DNA extraction method is a major factor in the ability to detect low levels of CMV in DBS and can largely account for the wide range of DBS sensitivities reported in studies to date.

Retrospective diagnosis of congenital cytomegalovirus infection in children with autism spectrum disorder but no other major neurologic deficit

AIM

Congenital cytomegalovirus (CMV) infection can cause a variety of neurological deficits of delayed onset in infants who are asymptomatic at birth. The aim of this study was to investigate the prevalence of congenital CMV infection among children with autism spectrum disorder (ASD) in Nagasaki, Japan.

METHODS

Twenty-nine children with ASD who were born in Nagasaki and had no other major neurological deficits were recruited. Two of the patients were excluded due to significant perinatal events. The remaining 27 children were investigated retrospectively for congenital CMV infection by analyzing dried blood spot samples or dried umbilical cords for CMV DNA using real-time PCR.

RESULTS

CMV DNA was detected in two (7.4%) of the 27 children. Neither of the patients had perinatal histories suggestive of congenital CMV disease or other neurological deficits, including hearing impairment and epilepsy. The severity of their autistic disorders varied considerably.

CONCLUSIONS

The rate of congenital CMV infection in this study (two of 27 children with ASD), which was significantly (p=0.004) higher than the incidence of congenital CMV infection in Nagasaki (0.31%, 10/3230 live births), suggests the involvement of congenital CMV infection in a portion of children with ASD, although definite diagnosis was not obtained due to limited clinical data of the study subjects.

Hearing loss and congenital CMV infection: a systematic review

BACKGROUND AND OBJECTIVE

Hearing loss caused by congenital cytomegalovirus (cCMV) infection was first observed in 1964. Today cCMV is the most common cause of nonhereditary sensorineural hearing loss in childhood. Our objective was to provide an overview of the prevalence of cCMV-related hearing loss, to better define the nature of cCMV-associated hearing loss, and to investigate the importance of cCMV infection in hearing-impaired children.

METHODS

Two reviewers independently used Medline and manual searches of references from eligible studies and review articles to select cohort studies on children with cCMV infection with audiological follow-up and extracted data on population characteristics and hearing outcomes.

RESULTS

Thirty-seven studies were included: 10 population-based natural history studies, 14 longitudinal cohort studies, and 13 retrospective studies. The prevalence of cCMV in developed countries is 0.58% (95% confidence interval, 0.41-0.79). Among these newborns 12.6% (95% confidence interval, 10.2-16.5) will experience hearing loss: 1 out of 3 symptomatic children and 1 out of 10 asymptomatic children. Among symptomatic children, the majority have bilateral loss; among asymptomatic children, unilateral loss predominates. In both groups the hearing loss is mainly severe to profound. Hearing loss can have a delayed onset, and it is unstable, with fluctuations and progression. Among hearing-impaired children, cCMV is the causative agent in 10% to 20%. Despite strict selection criteria, some heterogeneity was found between selected studies.

CONCLUSIONS

This systematic review underscores the importance of cCMV as a cause of sensorineural hearing loss in childhood.

Diagnosis and monitoring of cytomegalovirus infection by the quantification of viral load in dried blood spots samples

Cytomegalovirus (CMV) represents the major infectious cause of birth defects, as well as an important pathogen for immune-compromised individuals. Several studies described the use of dried blood spots (DBS) for the detection of CMV DNA for late diagnosis of congenital CMV infection in cases of strong clinical suspicion. In the article under evaluation, Limaye et al. perform for the first time the quantification of CMV in pairs of finger-stick DBS and plasma samples collected from transplant patients. The work concluded that finger-stick DBS could be an alternative sample type for quantification of CMV load that correlates well with plasma levels. Prospective trials to evaluate the use of DBS for monitoring CMV load in transplant recipients will be required.

A pilot study using residual newborn dried blood spots to assess the potential role of cytomegalovirus and Toxoplasma gondii in the etiology of congenital hydrocephalus

BACKGROUND

Congenital hydrocephalus is a condition characterized by accumulation of cerebrospinal fluid in the ventricles of the brain. Prenatal infections are risk factors for some birth defects. This pilot study investigated whether residual dried blood spots (DBS) could be used to assess infections as risk factors for birth defects by examining the associations between prenatal infection with Toxoplasma gondii (T. gondii) or cytomegalovirus (CMV) with congenital hydrocephalus.

METHODS

Case-infants with hydrocephalus (N=410) were identified among live-born infants using birth defects surveillance systems in California, North Carolina, and Texas. Control-infants without birth defects were randomly selected from the same geographic areas and time periods as case-infants (N=448). We tested residual DBS from case- and control-infants for T. gondii immunoglobulin M and CMV DNA. When possible, we calculated crude odds ratios (cORs) and confidence intervals (CIs).

RESULTS

Evidence for prenatal T. gondii infection was more common among case-infants (1.2%) than control-infants (0%; p=0.11), and evidence for prenatal CMV infection was higher among case-infants (1.5%) than control-infants (0.7%; cOR: 2.3; 95% CI: 0.48, 13.99).

CONCLUSIONS

Prenatal infections with T. gondii and CMV occurred more often among infants with congenital hydrocephalus than control-infants, although differences were not statistically significant. This pilot study highlighted some challenges in using DBS to examine associations between certain infections and birth defects, particularly related to reduced sensitivity and specimen storage conditions. Further study with increased numbers of specimens and higher quality specimens should be considered to understand better the contribution of these infections to the occurrence of congenital hydrocephalus.

Detection of infections with hepatitis B virus, hepatitis C virus, and human immunodeficiency virus by analyses of dried blood spots--performance characteristics of the ARCHITECT system and two commercial assays for nucleic acid amplification

BACKGROUND

Nowadays, dried blood spots (DBS) are primarily used to obtain diagnostic access to risk collectives such as intravenous drug users, who are prone to infections with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Before DBS analyses can be used in this diagnostic context, however, a comprehensive evaluation of its performance characteristics must be conducted. To the best of our knowledge, the current study presents for the first time such essential data for the Abbott ARCHITECT system, which is currently the worldwide leading platform in this field of infection diagnostics.

METHODS

The investigation comprised 1,762 paired serum/DBS samples and a total of 3,524 determinations with the Abbott ARCHITECT HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24-antigen/anti-HIV 1/2 assays as well as with the artus HBV LC PCR and VERSANT HCV RNA qualitative (TMA) tests.

RESULTS

In the context of DBS testing, a specificity of 100% was recorded for the seven serological and molecular biological assays. The analytical sensitivity of HBsAg, anti-HBc, anti-HBs, anti-HCV, HIV-1-p24-antigen/anti-HIV 1/2, HBV DNA, and HCV RNA detections in DBS eluates was 98.6%, 97.1%, 97.5%, 97.8%, 100%, 93%, and 100%, respectively.

DISCUSSION/CONCLUSIONS

The results obtained indicate that it is today possible to reliably detect HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24 antigen/anti-HIV 1/2 with state-of-the-art analytical systems such as the Abbott ARCHITECT in DBS eluates even when a comparatively high elution volume of 1,000 μl is used. They also provide evidence for the inherent analytical limits of DBS testing, which primarily concern the anti-HBc/anti-HBs system for individuals with HIV infections and nucleic acid tests with relatively low analytical sensitivity.

Congenital cytomegalovirus infection - a common cause of hearing loss of unknown aetiology

AIM

The aim of this study was to investigate the role of congenital cytomegalovirus (CMV) infection as a cause of various types of sensorineural hearing loss (SNHL) in a group of nonsyndromic children with otherwise unknown aetiology of hearing loss. Furthermore, the occurrence of combined congenital CMV infection and connexin 26 (Cx26) mutations was investigated.

METHODS

The dried blood spot (DBS) cards of 45 children with various degrees of hearing deficits and 46 children with severe/profound hearing loss were tested for CMV DNA with polymerase chain reaction (PCR) technique. The DBS cards of the 46 children with severe/profound hearing loss were also analysed for Cx26 mutations.

RESULTS

Of the 45 children with various degrees of hearing loss, nine were positive for CMV DNA (20%). The nine children represented severe/profound, mild and unilateral hearing loss. From the 46 children with severe/profound hearing loss, nine of 46 (20%) were positive for CMV DNA. In addition, three of the CMV DNA-positive children were carriers of mutations of Cx26.

CONCLUSION

Congenital CMV infection is a high risk factor in hearing impairment among children.

KI, WU, and Merkel cell polyomavirus DNA was not detected in guthrie cards of children who later developed acute lymphoblastic leukemia

BACKGROUND

Neonatal dried blood spots (Guthrie cards) have been used to demonstrate a prenatal origin of clonal leukemia-specific genetic aberrations in several subgroups of childhood acute lymphoblastic leukemia (ALL). One hypothesis suggests that an infectious agent could initiate genetic transformation already in utero. In search for a possible viral agent, Guthrie cards were analyzed for the presence of 3 newly discovered polyomavirus Karolinska Institutet polymavirus (KIPyV), Washington University polyomavirus (WUPyV), and Merkel cell polyomavirus (MCPyV).

METHODS

Guthrie cards from 50 children who later developed ALL and 100 matched controls were collected and analyzed by standard or real-time polymerase chain reaction for the presence of the VP1 region of KIPyV, WUPyV, and MCPyV, and the LT region for MCPyV.

RESULTS AND CONCLUSIONS

DNA from KIPyV, WUPyV, and MCPyV was not detected in neonatal blood samples from children with ALL or controls. Prenatal infections with these viruses are not likely to be etiological drivers for childhood leukemogenesis.

Overview of the diagnosis of cytomegalovirus infection

Cytomegalovirus (CMV) is recognized as the most common congenital viral infection in humans and an important cause of morbidity and mortality in immunocompromised hosts. This recognition of the clinical importance of invasive CMV disease in the setting of immunodeficiency and in children with congenital CMV infection has led to the development of new diagnostic procedures for the rapid identification of CMV. Diagnosis of acute maternal CMV infection by the presence of immunoglobulin (Ig)M and low-avidity IgG requires confirmation of fetal infection, which is typically performed using polymerase chain reaction (PCR) assays for CMV on amniotic fluid. Viral culture of the urine and saliva obtained within the first two weeks of life continues to be the gold standard for diagnosis of congenitally-infected infants. PCR assays of dried blood spots from newborns have been shown to lack sufficient sensitivity for the identification of most neonates with congenital CMV infection for universal screening purposes. However, saliva PCR assays are currently being assessed as a useful screening method for congenital CMV infection. In the immunocompromised host, newer rapid diagnostic assays, such as phosphoprotein 65 antigenemia and CMV real-time PCR of blood or plasma have allowed for preemptive treatment, reducing morbidity and mortality. However, lack of standardized real-time PCR protocols hinders the comparison of data from different centers and the development of uniform guidelines for the management of invasive CMV infections in immunocompromised individuals.

Extraction of DNA from dried blood in the diagnosis of congenital CMV infection

Viral DNA detection in dried blood spotted on filter paper, dried blood spots (DBS), is valuable in the diagnosis of viral infections, with at the moment congenital cytomegalovirus (CMV) being the most common application. CMV detection in clinical samples taken within the first 2-3 weeks after birth differentiates congenital CMV infection from the in general harmless postnatal acquired cytomegalovirus infection. DBS render the possibility to diagnose congenital CMV infection retrospectively, e.g., when late-onset hearing loss, the most frequently encountered symptom of congenital CMV infection, becomes manifest. Additionally, CMV DNA detection in DBS can be of usage in recently advocated newborn screening on congenital CMV infection. The procedure of CMV DNA detection in DBS consists of two separate steps: (1) DNA extraction from the DBS, followed by (2) CMV DNA amplification. Here, we describe two efficient methods for the extraction of DNA from DBS. Sensitivity, specificity, and applicability of the methods for high-throughput usage are discussed.

Rapid genotyping of cytomegalovirus in dried blood spots by multiplex real-time PCR assays targeting the envelope glycoprotein gB and gH genes

Genotyping of cytomegalovirus (CMV) is useful to examine potential differences in the pathogenicity of strains and to demonstrate coinfection with multiple strains involved in CMV disease in adults and congenitally infected newborns. Studies on genotyping of CMV in dried blood spots (DBS) are rare and have been hampered by the small amount of dried blood available. In this study, two multiplex real-time PCR assays for rapid gB and gH genotyping of CMV in DBS were developed. Validation of the assays with 39 CMV-positive plasma samples of transplant recipients and 21 urine specimens of congenitally infected newborns was successful in genotyping 100% of the samples, with gB1 and gB3 being the most prevalent genotypes. Multiple gB and gH genotypes were detected in 36% and 33% of the plasma samples, respectively. One urine sample from a newborn with symptomatic congenital CMV was positive for gB1 and gB2. DBS of congenitally infected newborns (n = 41) were tested using 9 μl of dried blood, and genotypes were detected in 81% (gB) and 73% (gH) of the samples, with gB3 being the most prevalent genotype. No clear association of specific genotypes with clinical outcome was observed. In conclusion, the CMV gB and gH PCR assays were found to be rapid, sensitive for detecting mixed infections, and suitable for direct usage on DBS. These assays are efficient tools for genotyping of CMV in DBS of congenitally infected newborns.

Congenital cytomegalovirus infection - An update

Cytomegalovirus is estimated to be the leading infectious cause of nonheriditary sensorneural loss and a significant cause of mental retardation. Approximately 1% of newborn infants are congenitally infected with the virus. This review summarizes recent developments concerning this infection, including clinical outcome, risk factors for aquisition diagnosis and therapy.

Implementing neonatal screening for congenital cytomegalovirus: addressing the deafness of policy makers

Congenital cytomegalovirus (CMV) infection is an important public health problem with approximately 7 in 1,000 newborns infected and consequently at risk for hearing impairment. Newborn hearing screening will fail to detect this hearing impairment in approximately half of the cases because late onset hearing loss is frequent. Hearing impairment has profound impact on cognitive and social development of children and their families, determining most of the disease burden of congenital CMV infection. The potential value of newborn screening for congenital CMV is increasingly discussed. To date, many experts acknowledge the benefit of antiviral treatment in the prevention of hearing deterioration in newborns with neurological symptoms, and the benefit of early identification of late-onset hearing impairment by means of extensive audiological follow up of infected infants. These opinions imply that the potential of newborn screening for CMV would lie in the identification of the large proportion of asymptomatic congenitally infected newborns at risk for developing late-onset hearing loss. Experience with postnatal antiviral treatment of symptomatic newborns is encouraging, but has not been studied in asymptomatic congenitally infected newborns. A large-scale study on the safety and effectiveness of combined screening and antiviral therapy for congenital CMV infection is the necessary next step to take and should not be delayed.

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.

Use of screening dried blood spots for estimation of prevalence, risk factors, and birth outcomes of congenital cytomegalovirus infection

OBJECTIVES

To determine the birth prevalence of cytomegalovirus (CMV) in a population-based sample of newborns by use of dried blood spots compared with previous studies that used established detection methods, and to evaluate risk factors and birth outcomes for congenital CMV infection.

STUDY DESIGN

A total of 3972 newborn dried blood spots collected for the California Newborn Screening Program were tested for presence of CMV DNA. Demographic and pregnancy data were obtained from linked newborn screening and live-birth records.

RESULTS

CMV prevalence among newborns by maternal race and ethnicity was 0.9% for blacks, 0.8% for Hispanics, 0.6% for whites, and 0.6% for Asians. Among Hispanics (n = 2053), infants who were infected had younger mothers (23 vs 26 years, P = .03), and prevalence was higher for children with no father information provided (2.6% vs 0.6%, P = .03). Overall CMV infection was associated with low birth weight (prevalence ratios [95% CI]: 3.4 [1.4-8.5]) and preterm birth (2.7 [1.4-5.1]). CMV viral loads were inversely related to birth weight and gestational age (both P = .03).

CONCLUSIONS

CMV prevalence measured with dried blood spots was similar to reports using standard viral culture methods. Dried blood spots may be suitable for detection of CMV infection in newborns and warrant further evaluation. Congenital CMV infection may contribute to low birth weight and preterm birth.

Influence of different extraction methods and PCR techniques on the sensitivity of HCMV-DNA detection in dried blood spot (DBS) filter cards

BACKGROUND

Infection with human cytomegalovirus (HCMV) is the most common congenital virus infection, affecting about 0.5-2% of newborns. Using DBS on Guthrie cards, it is possible to discriminate congenital from postnatal HCMV-infection. However, a recent European trial revealed serious problems in detection of low HCMV-DNA levels from DBS-filter-cards (Barbi et al., 2008).(7)

OBJECTIVES

Evaluation of the most sensitive combination of sample size, DNA extraction method and PCR system for the detection of low copy numbers of HCMV-DNA from DBS-filter-cards.

STUDY DESIGN

We compared three different manual extraction methods for the detection of HCMV-DNA out of DBS: the QIAmp-blood-Mini-Kit, a heat-extraction-method and traditional phenol-chloroform extraction. Additionally, we tested an automated nucleic acid extraction system (NucliSense EasyMag/Biomerieux). Different punch-sizes of DBS spiked with defined HCMV AD169-DNA copy numbers were analyzed. For detection, we used a quantitative in-house-LightCycler-PCR targeting the gB-region using the hybridisation-probe-format. We compared the sensitivity of the real-time-PCR with IE1Ex4-targeted nested-PCR.

RESULTS

The highest sensitivity with 200 copies HCMV DNA/ml was achieved using the phenol-chloroform method in combination with the nested-PCR and 6mm, 3x3mm punches or the whole DBS. The QIAmp-blood-Mini-Kit also showed a very high sensitivity by using the whole DBS and the nested-PCR.

CONCLUSION

These results may have strong implications for retrospective diagnosis of congenital HCMV (cHCMV) infection, since a defined combination of the area of punch, the extraction method, and PCR method determine the probability of detection of viral DNA from DBS according to a logistic model.

Dried blood spot real-time polymerase chain reaction assays to screen newborns for congenital cytomegalovirus infection

CONTEXT

Reliable methods to screen newborns for congenital cytomegalovirus (CMV) infection are needed for identification of infants at increased risk of hearing loss. Since dried blood spots (DBS) are routinely collected for metabolic screening from all newborns in the United States, there has been interest in using DBS polymerase chain reaction (PCR)-based methods for newborn CMV screening.

OBJECTIVE

To determine the diagnostic accuracy of DBS real-time PCR assays for newborn CMV screening.

DESIGN, SETTING, AND PARTICIPANTS

Between March 2007 and May 2008, infants born at 7 US medical centers had saliva specimens tested by rapid culture for early antigen fluorescent foci. Results of saliva rapid culture were compared with a single-primer (March 2007-December 2007) and a 2-primer DBS real-time PCR (January 2008-May 2008). Infants whose specimens screened positive on rapid culture or PCR had congenital infection confirmed by the reference standard method with rapid culture testing on saliva or urine.

MAIN OUTCOME MEASURES

Sensitivity, specificity, and positive and negative likelihood ratios (LRs) of single-primer and 2-primer DBS real-time PCR assays for identifying infants with confirmed congenital CMV infection.

RESULTS

Congenital CMV infection was confirmed in 92 of 20,448 (0.45%; 95% confidence interval [CI], 0.36%-0.55%) infants. Ninety-one of 92 infants had positive results on saliva rapid culture. Of the 11,422 infants screened using the single-primer DBS PCR, 17 of 60 (28%) infants had positive results with this assay, whereas, among the 9026 infants screened using the 2-primer DBS PCR, 11 of 32 (34%) screened positive. The single-primer DBS PCR identified congenital CMV infection with a sensitivity of 28.3% (95% CI, 17.4%-41.4%), specificity of 99.9% (95% CI, 99.9%-100%), positive LR of 803.7 (95% CI, 278.7-2317.9), and negative LR of 0.7 (95% CI, 0.6-0.8). The positive and negative predictive values of the single-primer DBS PCR were 80.9% (95% CI, 58.1%-94.5%) and 99.6% (95% CI, 99.5%-99.7%), respectively. The 2-primer DBS PCR assay identified infants with congenital CMV infection with a sensitivity of 34.4% (95% CI, 18.6%-53.2%), specificity of 99.9% (95% CI, 99.9%-100.0%), positive LR of 3088.9 (95% CI, 410.8-23 226.7), and negative LR of 0.7 (95% CI, 0.5-0.8). The positive and negative predictive values of the 2-primer DBS PCR were 91.7% (95% CI, 61.5%-99.8%) and 99.8% (95% CI, 99.6%-99.9%), respectively.

CONCLUSION

Among newborns, CMV testing with DBS real-time PCR compared with saliva rapid culture had low sensitivity, limiting its value as a screening test.

Adenovirus DNA in Guthrie cards from children who develop acute lymphoblastic leukaemia (ALL)

BACKGROUND

In search of a proposed viral aetiology of childhood acute lymphoblastic leukaemia (ALL), the common species C adenoviruses were analysed in Guthrie cards.

METHODS

Guthrie cards from 243 children who later developed ALL and from 486 matched controls were collected and analysed by nested polymerase chain reaction for the presence of adenovirus DNA.

RESULTS

Adenovirus DNA was reliably detected from only two subjects, both of whom developed ALL.

CONCLUSION

Adenovirus DNA is detected in Guthrie card samples at too low a frequency to reveal an association between adenovirus and the development of leukaemia.

Detection of cytomegalovirus DNA in dried blood spots of Minnesota infants who do not pass newborn hearing screening

BACKGROUND

Up to 15% of infants with asymptomatic congenital cytomegalovirus (CMV) infection will experience some degree of sensorineural hearing loss. Many infants who fail newborn hearing screening (NHS) are likely to have congenital CMV infection, but may escape definitive virologic identification because diagnostic evaluation may not commence until several weeks or months of age, making differentiation between congenital and postnatal CMV infection difficult. Early diagnosis linking virologic identification of congenital CMV infection to infants failing NHS may improve diagnostic precision and enhance opportunities for therapeutic intervention.

METHODS

The goal of this study was to compare newborn dried blood spots from Minnesota infants who had failed NHS, and were designated for referral, with control infants who passed NHS, for the presence of CMV DNA by real-time PCR, using hybridization probes for the CMV gene UL54.

RESULTS

Of 479 infants with a failed NHS (bilateral failure), 13 had CMV DNA present in the blood spot (2.7%). This compared with only 2/479 positive results from a control group of infants who passed the NHS (0.4%; P = 0.007, Fisher exact test). Comparisons of the glycoprotein B (gB) genotype as well as direct DNA sequencing of selected positives revealed that PCR positive samples represented unique clinical isolates. The mean viral load among the 15 positive samples was 1.6 x 10(3) genomes/microgram of total DNA.

CONCLUSIONS

Newborn bloodspot CMV screening by real-time PCR may be a useful and rapid adjunct to functional NHS and may enable more rapid etiologic diagnosis of sensorineural hearing loss in newborns.

[Retrospective diagnosis of congenital CMV infection in DBS from Guthrie cards: French experience]

Systematic screening for cytomegalovirus congenital infection is not performed in France. For children with hearing loss or other neurological CMV compatible symptoms, retrospective diagnosis is possible by PCR detection of CMV DNA in dried blood spot of neonatal Guthrie cards. We report here the results obtained with this technique in the French national reference laboratory for cytomegalovirus.

Teratology: from science to birth defects prevention

One of the goals of birth defects research is to better understand risk or preventive factors for birth defects so that strategies for prevention can be developed. In this article, we have selected four areas of birth defects research that have led to the development of prevention strategies. These areas include rubella virus as a cause of congenital rubella syndrome, folic acid as a preventive factor for neural tube defects, cytomegalovirus infection as a cause of birth defects and developmental disabilities, and alcohol as a cause of fetal alcohol spectrum disorders. For each of these areas, we review key clinical and research findings that led to the identification of the risk or preventive factor, milestones in the development of prevention strategies, and the progress made thus far toward prevention.

Etiologic and audiologic evaluations after universal neonatal hearing screening: analysis of 170 referred neonates

OBJECTIVE

The goal was to clarify the audiologic aspects and causes of congenital hearing loss in children who failed universal neonatal hearing screening.

METHODS

A prospective analysis of 170 consecutive records of neonates referred to a tertiary center after universal neonatal hearing screening failure, between 1998 and 2006, was performed. The data presented here represent the equivalent of approximately 87000 screened newborns. The screening results were validated with a clinical ear, nose, and throat examination and electrophysiological testing, including diagnostic auditory brainstem response, automated steady state response, and/or behavioral testing. A diagnostic evaluation protocol for identification of the cause of the hearing loss was also implemented, in collaboration with the departments of genetics and pediatrics.

RESULTS

Permanent hearing loss was confirmed in 116 children (68.2%). Bilateral hearing loss was diagnosed in 68 infants (58.6%) and unilateral hearing loss in 48 infants (41.4%). Median thresholds for the neonates with confirmed hearing loss were severe in both unilateral and bilateral cases, at 70 dB nHL and 80 dB nHL, respectively. In 55.8% of those cases, no risk factors for hearing loss were found. In 60.4%, the initial automated auditory brainstem response diagnosis was totally in agreement with the audiologic evaluation results. In 8.3% of the cases, however, a unilateral refer result was finally classified as bilateral hearing loss. An etiologic factor could be identified in 55.2% of the cases. Of the causes identified, a genetic mechanism was present in 60.4% of the cases, peripartal problems in 20.8%, and congenital cytomegalovirus infection in 18.8%.

CONCLUSIONS

An etiologic factor could be identified for nearly one half of the children with confirmed congenital hearing loss referred through a universal hearing screening program.

Evaluation of different cytomegalovirus (CMV) DNA PCR protocols for analysis of dried blood spots from consecutive cases of neonates with congenital CMV infections

Two protocols for the extraction of cytomegalovirus (CMV) DNA and two methods for the amplification of CMV DNA in dried blood spots were evaluated for the retrospective diagnosis of congenital CMV infection. During the period from 1996 to 2006, a urine screening program detected 76 congenitally infected neonates. Stored Guthrie cards with blood from 55 cases and 12 controls were tested. Two spots of dried blood were cut from each card and evaluated in two centers. CMV DNA was extracted from a whole single spot. Center 1 used phenol-chloroform extraction and ethanol precipitation followed by a conventional PCR. Center 2 used the NucliSens easyMAG automated DNA/RNA extraction platform (bioMérieux) followed by a real-time PCR. For evaluation of the extraction method, DNA extracted from each blood spot was evaluated by the amplification method used by the collaborating center. The sensitivities were 66% for center 1 and 73% for center 2. None of the controls were positive. A sensitivity as high as 82% could be obtained by combining the most sensitive extraction method (the phenol-chloroform procedure) with the most sensitive PCR method (real-time PCR). The detection rate was not influenced by the duration of storage of the spots. The sensitivity was higher with blood from congenitally infected cases due to a primary maternal CMV infection, regardless of the protocol used. However, the difference reached significance only for the least-sensitive protocol (P = 0.036).

Adenovirus DNA is detected at increased frequency in Guthrie cards from children who develop acute lymphoblastic leukaemia

Epidemiological evidence suggests that childhood acute lymphoblastic leukaemia (ALL) may be initiated by an in infection in utero. Adenovirus DNA was detected in 13 of 49 neonatal blood spots from ALL patients but only in 3 of 47 controls (P=0.012) suggesting a correlation between prenatal adenovirus infection and the development of ALL