Cytomegalovirus DNA detection in Guthrie cards: a powerful tool for diagnosing congenital infection

Congenital Cytomegalovirus Testing Outcomes From the ValEAR Trial

OBJECTIVE

To determine the positivity rate of congenital cytomegalovirus (cCMV) testing among universal, hearing-targeted CMV testing (HT-cCMV) and delayed targeted dried blood spot (DBS) testing newborn screening programs, and to examine the characteristics of successful HT-cCMV testing programs.

STUDY DESIGN

Prospective survey of birth hospitals performing early CMV testing.

SETTING

Multiple institutions.

METHODS

Birth hospitals participating in the National Institutes of Health ValEAR clinical trial were surveyed to determine the rates of cCMV positivity associated with 3 different testing approaches: universal testing, HT-cCMV, and DBS testing. A mixed methods model was created to determine associations between successful HT-cCMV screening and specific screening protocols.

RESULTS

Eighty-two birth hospitals were surveyed from February 2019 to December 2021. Seven thousand six hundred seventy infants underwent universal screening, 9017 infants HT-cCMV and 535 infants delayed DBS testing. The rates of cCMV positivity were 0.5%, 1.5%, and 7.3%, respectively. The positivity rate for universal CMV screening was less during the COVID-19 pandemic than that reported prior to the pandemic. There were no statistically significant drops in positivity for any approach during the pandemic. For HT-cCMV testing, unique order sets and rigorous posttesting protocols were associated with successful screening programs.

CONCLUSION

Rates of cCMV positivity differed among the 3 approaches. The rates are comparable to cohort studies reported in the literature. Universal CMV prevalence decreased during the pandemic but not significantly. Institutions with specific order set for CMV testing where the primary care physician orders the test and the nurse facilitates the testing process exhibited higher rates of HT-cCMV testing.

Maternal and congenital human cytomegalovirus infection: laboratory testing for detection and diagnosis

Human cytomegalovirus (CMV) is the leading cause of congenital infection worldwide and the most common cause of non-genetic sensorineural hearing loss. As there is no vaccine or other specific intervention to prevent congenital CMV infection, there is a need to identify maternal and congenital infections with sensitive and specific testing as early as possible. There is no widely accepted practice for screening during pregnancy or in all newborns for identification of possible cases of congenital CMV. Currently, screening during pregnancy is limited to those identified as at risk followed by fetal and/or neonatal testing when congenital infection is suspected. This review focuses primarily on the current status of laboratory testing for diagnosis of maternal and congenital CMV infections. Primary maternal infection is best diagnosed using serologic testing, including CMV IgM, IgG, and avidity testing, while fetal infection should be assessed by nucleic acid amplification testing (NAAT) of amniotic fluid. Urine and saliva NAATs are the mainstay for diagnosis of congenital CMV in the first 3 weeks of life. Testing of dried blood spots can be useful for diagnosis of congenital CMV outside of the newborn period. The gaps in knowledge such as the prognostic value of viral loads in various sample types are addressed.

Utility of Dried Blood Spots for the Diagnosis of Congenital Cytomegaloviruses within the First 21 Days of Life in a Single Center

In this retrospective study, we aimed to evaluate the performance of dried-blood-spot (DBS) testing as a diagnostic method for the congenital cytomegalovirus (cCMV). We reviewed the medical records and DBS test results of 89 patients who had also undergone diagnostic cCMV testing within the first 21 days of life. The DBS test had a sensitivity of 83.9%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 73%. Patients with a true-positive DBS had a higher median level of CMV in blood according to PCR than those with a false-negative result. Additionally, all patients with cCMV and hearing loss had a positive DBS test, with higher median viremia levels observed in those with hearing loss compared to those without a CMV PCR blood test. These results suggest that DBS-based testing is useful in the diagnosis of cCMV, and its performance may be related to levels of CMV viremia. DBS testing accurately identified those patients with congenital/early onset hearing loss and those at risk of developing late-onset hearing loss.

Clinical outcome and the role of antivirals in congenital cytomegalovirus infection

Congenital cytomegalovirus (cCMV) infection is a leading cause of hearing loss and neurological disabilities in children worldwide. Although a minority of infants with cCMV will have symptoms at a birth, these children are at high risk of long-term sequelae. Most infants with cCMV have no clinical signs at birth (asymptomatic), but 10-15% will develop hearing loss. The diagnosis of cCMV relies on detection of the virus from urine or saliva within the first three weeks of life, with saliva PCR being the preferred method due to ease of collection and high sensitivity of the assay. Measures to prevent mother-to-child transmission of CMV are limited, and antiviral therapy with valganciclovir for 6 months is the standard of care for infants with symptomatic cCMV. As more infants with cCMV are being identified through newborn screening, studies are urgently needed to address antiviral treatment in asymptomatic infants and the implementation of prevention strategies to prevent fetal infection. This article is part of the symposium "New drugs and vaccines for DNA virus infections: a symposium in memory of Mark Prichard."

The frequency of cytomegalovirus non-ELR UL146 genotypes in neonates with congenital CMV disease is comparable to strains in the background population

Background

Congenital cytomegalovirus disease (cCMV) is common and can be fatal or cause severe sequelae. Circulating strains of cytomegalovirus carry a high number of variable or disrupted genes. One of these is UL146, a highly diverse gene with 14 distinct genotypes encoding a CXC-chemokine involved in viral dissemination. UL146 genotypes 5 and 6 lack the conserved ELR motif, potentially affecting strain virulence. Here, we investigate whether UL146 genotypes 5 and 6 were associated with congenital CMV infection.

Methods

Viral DNA was extracted and UL146 sequenced from 116 neonatal dried blood spots (DBS) stored in the Danish National Biobank since 1982 and linked to registered cCMV cases through a personal identifier. These sequences were compared to UL146 control sequences obtained from CMV DNA extracted from 83 urine samples from children with suspected bacterial urinary tract infections.

Results

Three non-ELR UL146 genotypes (5 and 6) were observed among the cases (2.6%) and two were observed among the controls (2.4%; P > 0.99). Additionally, no significant association with cCMV was found for the other 12 genotypes in a post-hoc analysis, although genotype 8 showed a tendency to be more frequent among cases with 12 observations against three (P = 0.10). All fourteen genotypes were found to have little intra-genotype variation. Viral load, gender, and sample age were not found to be associated with any particular UL146 genotype.

Conclusions

No particular UL146 genotype was associated with cCMV in this nationwide retrospective case-control study. Associations between CMV disease and disrupted or polymorph CMV genes among immunosuppressed people living with HIV/AIDS and transplant recipients should be investigated in future studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06076-w.

Timing of newborn hearing screening in the neonatal intensive care unit: implications for targeted screening for congenital cytomegalovirus infection

OBJECTIVE

To determine when infants in the neonatal intensive care unit (NICU) have the first hearing screen performed, and thus inform targeted testing for cytomegalovirus (CMV)-related hearing loss.

STUDY DESIGN

Retrospective review of electronic health records of infants admitted to a Level 4 outborn NICU and had a first hearing screen performed from 8/2016-8/2018.

RESULT

Among 1498 infants, 546 (36%) had a first hearing screen performed at age >21 days when a positive CMV PCR test cannot distinguish congenital from postnatal CMV acquisition. While most infants tested at >21 days of age were <34 weeks' gestational age (71%), 18% (n = 100) and 11% (n = 59) were ≥34 and ≥37 weeks' gestation, respectively.

CONCLUSION

Targeted CMV testing for failed hearing screen in the NICU is problematic as 36% of infants did not have a hearing screen performed before 21 days of age, supporting the need for CMV screening at NICU admission.

Congenital Cytomegalovirus Infection

Congenital cytomegalovirus (cCMV) infection is a leading cause of hearing loss and neurological disabilities in children, with the disease burden and disabilities due to cCMV greater than many other well recognized childhood conditions. A minority of infants with cCMV will have symptoms at birth. Infants with symptomatic cCMV are at higher risk for sequelae than those born without symptoms. The majority of infants with cCMV are asymptomatic at birth, but 10%-15% will develop hearing loss. Although clinical symptoms can help predict which infants will have sensorineural hearing loss, among asymptomatic cCMV there are currently no predictors of adverse outcome. The identification of a biomarker to identify those at highest risk of sequelae is highly desirable to target interventions to those who could potentially benefit. Because there is increasing rationale for establishing both targeted and universal screening programs for cCMV in the United States and worldwide, this is an urgent priority.

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.

Second-Tier Next Generation Sequencing Integrated in Nationwide Newborn Screening Provides Rapid Molecular Diagnostics of Severe Combined Immunodeficiency

Severe combined immunodeficiency (SCID) and other T cell lymphopenias can be detected during newborn screening (NBS) by measuring T cell receptor excision circles (TRECs) in dried blood spot (DBS) DNA. Second tier next generation sequencing (NGS) with an amplicon based targeted gene panel using the same DBS DNA was introduced as part of our prospective pilot research project in 2015. With written parental consent, 21 000 newborns were TREC-tested in the pilot. Three newborns were identified with SCID, and disease-causing variants in IL2RG, RAG2, and RMRP were confirmed by NGS on the initial DBS DNA. The molecular findings directed follow-up and therapy: the IL2RG-SCID underwent early hematopoietic stem cell transplantation (HSCT) without any complications; the leaky RAG2-SCID received prophylactic antibiotics, antifungals, and immunoglobulin infusions, and underwent HSCT at 1 year of age. The child with RMRP-SCID had complete Hirschsprung disease and died at 1 month of age. Since January 2018, all newborns in Norway have been offered NBS for SCID using 1st tier TRECs and 2nd tier gene panel NGS on DBS DNA. During the first 20 months of nationwide SCID screening an additional 88 000 newborns were TREC tested, and four new SCID cases were identified. Disease-causing variants in DCLRE1C, JAK3, NBN, and IL2RG were molecularly confirmed on day 8, 15, 8 and 6, respectively after birth, using the initial NBS blood spot. Targeted gene panel NGS integrated into the NBS algorithm rapidly delineated the specific molecular diagnoses and provided information useful for management, targeted therapy and follow-up i.e., X rays and CT scans were avoided in the radiosensitive SCID. Second tier targeted NGS on the same DBS DNA as the TREC test provided instant confirmation or exclusion of SCID, and made it possible to use a less stringent TREC cut-off value. This allowed for the detection of leaky SCIDs, and simultaneously reduced the number of control samples, recalls and false positives. Mothers were instructed to stop breastfeeding until maternal cytomegalovirus (CMV) status was determined. Our limited data suggest that shorter time-interval from birth to intervention, may prevent breast milk transmitted CMV infection in classical SCID.

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.

Loop mediated isothermal amplification (LAMP) of Toxoplasma DNA from dried blood spots

INTRODUCTION

The cosmopolitan protozoan Toxoplasma gondii is a major parasite of warm-blooded animals including man. Early and accurate diagnosis is a must for proper treatment that prevents life threatening sequels. Loop-mediated isothermal amplification (LAMP) is a novel technique that can amplify DNA with high sensitivity and specificity under isothermal conditions.

AIM OF THE STUDY

To validate a LAMP-specific protocol for detection of Toxoplasma DNA using dried blood spots (DBS) from mice experimentally infected with the cystogenic Toxoplasma ME-49 strain.

METHODS

In this study, the target DNA fragment was the Toxoplasma 529-bp repeat element that exists in 200-300 copies per T. gondii genome. The sensitivity of both LAMP and conventional PCR techniques was estimated in DBS samples from experimental mice at 1-week and 8-weeks post-infection.

RESULTS

Out of 20 blood samples gathered on Whatman filter paper from mice at 1-week post-infection, 18 and 16 were positive by LAMP and conventional PCR, respectively. Neither techniques detected parasite DNA in blood at 8th week of infection.

CONCLUSION

Dried blood spots are easy source of material for molecular studies. LAMP assay proved higher sensitivity than the conventional PCR in detecting parasitemia in early infection with the cystogenic Toxoplasma strain.

Blood viral load in the diagnostic workup of congenital cytomegalovirus infection

BACKGROUND

There is limited data on the role of cytomegalovirus (CMV) blood quantitative polymerase chain reaction (qPCR) in the diagnostic workup of congenital CMV (cCMV) infection.

OBJECTIVES

The objective of this study was to determine if CMV blood qPCR at the time diagnosis could differentiate between symptomatic and asymptomatic infants according to the recent consensus classification.

STUDY DESIGN

Retrospective study of children diagnosed with cCMV infection at CHU Sainte-Justine, Montreal, Canada, between 2008 and 2016. Cases for whom qPCR was done at baseline (<4 weeks of age) alongside a complete diagnostic workup were included. The association between CMV blood viral load (VL) and clinical severity group was determined. The probability of having moderate to severe symptoms was assessed using univariate logistic regression analysis.

RESULTS

Forty-seven patients were included in the analysis. Median VL was significantly higher among infants with moderate to severely symptomatic disease vs. those asymptomatic or asymptomatic with isolated sensorineural hearing loss (SNHL) (13 736 vs. 1876 copies/ml, p = 0.004), infants with moderate to severe disease or asymptomatic with isolated SNHL vs. asymptomatic (17 736 vs. 1496 copies/ml, p < 0.001), and in infants with baseline neurological involvement vs. those without (17 317 vs. 2641 copies/ml, p = 0.03). Using logistic regression, an infant would have a >75 % probability of being moderate to severely symptomatic above 18 770 copies/ml, with a threshold of 100 000 copies/ml approaching a 100 % probability.

CONCLUSIONS

Our baseline assessment of CMV blood VL suggests that that the level of CMV viremia correlates with symptom severity.

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.

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.

Nutrition of Preterm Infants and Raw Breast Milk-Acquired Cytomegalovirus Infection: French National Audit of Clinical Practices and Diagnostic Approach

Raw breast milk is the optimal nutrition for infants, but it is also the primary cause of acquired cytomegalovirus (CMV) infection. Thus, many countries have chosen to contraindicate to feed raw breast milk preterm infants from CMV-positive mothers before a corrected age of 32 weeks or under a weight of 1500 g. French national recommendations have not been updated since 2005. An audit of the French practices regarding the nutrition with raw breast milk in preterm infants was carried out using a questionnaire sent to all neonatal care units. Diagnosed postnatal milk-acquired CMV infections have been analysed using hospitalisation reports. Seventy-five percent of the neonatal units responded: 24% complied with the French recommendations, 20% contraindicated raw breast milk to all infants before 32 weeks regardless of the mothers' CMV-status, whereas 25% fed all preterm infants unconditionally with raw breast milk. Thirty-five cases of infants with milk-acquired CMV infections have been reported. The diagnosis was undeniable for five patients. In France, a high heterogeneity marks medical practices concerning the use of raw breast milk and the diagnostic approach for breast milk-acquired CMV infection is often incomplete. In this context, updated national recommendations and monitored CMV infections are urgently needed.

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.

Nucleic Acid Extraction and Enrichment

Nucleic acid extraction is the first step of any amplification experiment no matter what kind of amplification is used to detect a specific pathogen. Efficient nucleic acid extraction is essential to obtain good results using any molecular test. The optimal extraction method should fulfill the following conditions: speed, short working time, cost-effectiveness, high sensitivity and specificity, good reproducibility, and safety. The methods can be divided into solution or column based according to differences of their principles. The automated extraction instruments have many advantages, and these have proven to be very useful. Moreover, in recent years, fully automated instruments combining NA extraction and amplification have been commercially available. However, the method itself does not provide assurance, and the DNA recovery can be different among various kits or instruments that use the similar principles. Therefore, it is important to carefully evaluate the performance of any extraction method used in the clinical microbiology laboratory even though manufacturers may have reported good validation results with specific organisms.

Detection of congenital cytomegalovirus in newborns using nucleic acid amplification techniques and its public health implications

Human cytomegalovirus (HCMV), a herpesvirus, is an important human pathogen that causes asymptomatic infections in healthy or immunocompetent individuals but can lead to severe and potentially life-threatening complications in immune-immature individuals such as neonates or immune-compromised patients such as organ-transplant recipients and HIV-positive individuals. Congenital HCMV infection represents a significant public health issue and poses substantial healthcare and economic burden to society. This virus causes the most common viral congenital infection worldwide, and is the leading non-genetic cause of sensorineural hearing loss in children in developed countries. Congenital HCMV infection is believed to fulfill the criteria of the American College of Medical Genetics to be considered as a condition targeted for a newborn screening program. This is because congenital HCMV infection can be identified during a time (within 2 days after birth) at which it would not ordinarily be detected clinically, and there are demonstrated benefits of early detection, timely intervention, and efficacious treatment of the condition. Recent progresses in developing polymerase chain reaction-based approaches to detect HCMV in samples obtained from newborns have generated much excitement in the field. In this review, we highlight the recent progress in diagnostic techniques that could potentially be used for the detection of HCMV infection in neonates and its direct implications in public health settings for diagnosing congenital HCMV infection.

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.

Cytomegalovirus

Cytomegalovirus (CMV), the largest of the herpesviruses, causes a wide range of clinical syndromes, from asymptomatic infection to severe disease in immunocompromised hosts. Laboratory methods for diagnosis include molecular testing, antigenemia, culture, serology, and histopathology. Treatment of CMV infection and disease is indicated in selected immunocompromised hosts, and preventive approaches are indicated in high-risk groups. This chapter reviews the epidemiology, clinical aspects, and the laboratory diagnosis and management of CMV in immunocompromised hosts.

Severe neonatal cytomegalovirus infection: about a case

Maternofoetal infection with Cytomegalovirus (CMV) is the most common congenital infection and a leading cause of mental retardation and sensori-neural hearing loss. Population-based studies indicate that at least 0.5% of all infants born alive have CMV of whom approximately 10% have clinically evident symptomsat birth. The Justification of systematic screening for foetal CMV infection is still controversial and is not recommended in most developed countries. This is mainly justified by the paucity of antenatal prognostic factors and the lack of established intrauterine treatment when foetal infection has been diagnosed. In case of congenital CMV infection, infants can be symptomatic or asymptomatic at birth. Mortality for such infants can reach 30%, and survivors can have mental retardation, sensorineural hearing loss, chorioretinitis, and other significant medical problems. A newborn symptomatic is defined by the existence of clinical and / or biological signs and / or neonatal imaging, the most frequent clinical signs are: hepatosplenomegaly (60%), microcephaly (53%), jaundice (67%), petechiae (76%), at least one neurological abnormality (68%). The frequency of biological abnormalities is as follows: increase in transaminases (83%), thrombocytopenia (77%), hyperbilirubinemia (69%), haemolysis (51%), hyperproteinorrachy (46%). The abnormalities of neonatal imaging are present in 70% of symptomatic newborns; intracerebral calcifications are the most frequent abnormalities. We report a case of newborn who presented a congenital infection by CMV, evoked on the intrauterine growth retardation, organs of the reticulo endothelial and haematological system were reached while nervous system was spared, and CMV PCR was very positive. indicating an antiviral treatment for 6weeks based on ganciclovir.

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.

Cholestasis caused by panhypopituitarism and acquired cytomegalovirus infection in a 2-month-old male infant: A case report

RATIONALE

Septo-optic dysplasia (SOD) is a rare congenital disorder that may cause jaundice in infants. However, it is usually prone to neglect and misdiagnosis in infants with cholestasis because endocrine disorder such as panhypopituitarism is rare in the cause of infantile cholestasis. We report a case of SOD concurrent with acquired cytomegalovirus (CMV) infection, who presented with prolonged jaundice as the first clinical sign.

PATIENT CONCERNS

The patient was a 2-month-old male infant who presented with cholestasis, combined with fever and panhypopituitarism.

DIAGNOSES

He was diagnosed with SOD and acquired CMV infection.

INTERVENTIONS

He was treated with hormone replacement therapy and ganciclovir.

OUTCOMES

After correction of the pituitary hormone deficiency and ganciclovir treatment, significant improvements of cholestasis, retinal lesions, and growth rate were seen in our patient.

LESSONS

Although an endocrine disorder such as panhypopituitarism is rare in the cause of neonatal or infantile cholestasis, we must keep this reason in mind.

Vertically transmitted cytomegalovirus infection in newborn preterm infants

OBJECTIVE

To determine the epidemiology of congenital and acquired cytomegalovirus (CMV) infections in preterm infants and to analyze the efficacy of breast milk freezing in decreasing the vertical transmission rate of CMV.

STUDY DESIGN

During 2013 and 2014, preterm newborns who weighed ≤1500 g and were admitted to 22 Spanish neonatal units were included and screened for CMV infection according to the Spanish Neonatology Society recommendations. Each hospital treated the breast milk according to its own protocols.

RESULTS

Among the 1236 preterm neonates included, 10 had a congenital infection (0.8%) and 49 had an acquired infection (4.0%) (82% demonstrated positive PCR-CMV in breast milk). The neonates who received only frozen milk presented less frequently with acquired infection (1.2%) than those fed fresh milk (5.5%) (RR=0.22; 95% CI 0.05-0.90; P=0.017). The newborns who received bank milk followed by frozen or fresh breast milk more frequently had an acquired infection (2.1% or 2.2%, respectively) than those fed only frozen breast milk.

CONCLUSIONS

The incidence of congenital CMV infection in our sample is low, as described in the literature. To reduce acquired CMV infection, freezing breast milk might be an advisable procedure for preterm neonates born from seropositive mothers, either from the beginning of lactation or after a period of bank milk administration.

Prenatal acquired cytomegalovirus infection should be considered in children with autism

AIM

The aim of the study was to evaluate the prevalence of congenital cytomegalovirus infection (CMV) in a representative sample of children with autism spectrum disorder.

METHODS

In a representative group of 115 preschool children with autism spectrum disorder, of whom 33 also had intellectual disability, the dried blood spots from the newborn metabolic screening were analysed for CMV DNA using TaqMan polymerase chain reaction.

RESULTS

One of the 33 children with autism spectrum disorder and intellectual disability - 3% of that group - had congenital CMV infection. The corresponding prevalence in newborn infants in Sweden is 0.2%. None of the 82 children without intellectual disability had congenital CMV.

CONCLUSION

The finding lends some further support for congenital CMV being one of the many aetiologies underlying autism spectrum disorder with intellectual disability. The rate of 3% of congenital CMV in children with autism spectrum disorder with intellectual disability has implications for the medical work-up. The finding of congenital CMV also indicates the need for repeated hearing assessments in the child. There is a need for similar studies with much larger samples.

Dried blood spots PCR assays to screen congenital cytomegalovirus infection: a meta-analysis

The performance of dried blood spots (DBS) polymerase chain reaction (PCR) assays in screening for congenital cytomegalovirus (cCMV) infection varies between different studies. To determine whether the DBS PCR assay has sufficient accuracy to be used as a screening test for cCMV infection, we performed a meta-analysis of 15 studies (n = 26007 neonates) that evaluated the performance of DBS PCR tests in screening for cCMV infection and that met our inclusion criteria. The pooled sensitivity and specificity were 0.844 (95% CI = 0.812–0.872) and 0.999 (95% CI = 0.998–0.999), respectively, and the diagnostic odds ratio was 1362.10 (95%CI = 566.91–3272.60). As sensitivity analysis showed that the results were robust. In conclusion, the performance of DBS PCR assays for testing cCMV was more suitable for retrospective diagnosis than screening.

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.

Repeated measures study of weekly and daily cytomegalovirus shedding patterns in saliva and urine of healthy cytomegalovirus-seropositive children

Background

To better understand potential transmission risks from contact with the body fluids of children, we monitored the presence and amount of CMV shedding over time in healthy CMV-seropositive children.

Methods

Through screening we identified 36 children from the Atlanta, Georgia area who were CMV-seropositive, including 23 who were shedding CMV at the time of screening. Each child received 12 weekly in-home visits at which field workers collected saliva and urine. During the final two weeks, parents also collected saliva and urine daily.

Results

Prevalence of shedding was highly correlated with initial shedding status: children shedding at the screening visit had CMV DNA in 84% of follow-up saliva specimens (455/543) and 28% of follow-up urine specimens (151/539); those not shedding at the screening visit had CMV DNA in 16% of follow-up saliva specimens (47/303) and 5% of follow-up urine specimens (16/305). Among positive specimens we found median viral loads of 82,900 copies/mL in saliva and 34,730 copies/mL in urine (P = 0.01), while the viral load for the 75th percentile was nearly 1.5 million copies/mL for saliva compared to 86,800 copies/mL for urine. Younger age was significantly associated with higher viral loads, especially for saliva (P < 0.001). Shedding prevalence and viral loads were relatively stable over time. All children who were shedding at the screening visit were still shedding at least some days during weeks 11 and 12, and median and mean viral loads did not change substantially over time.

Conclusions

Healthy CMV-seropositive children can shed CMV for months at high, relatively stable levels. These data suggest that behavioral prevention messages need to address transmission via both saliva and urine, but also need to be informed by the potentially higher risks posed by saliva and by exposures to younger children.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0569-1) contains supplementary material, which is available to authorized users.

Cross-sectional study of cytomegalovirus shedding and immunological markers among seropositive children and their mothers

Background

Congenital cytomegalovirus (CMV) is the leading infectious cause of birth defects in the United States. To better understand factors that may influence CMV transmission risk, we compared viral and immunological factors in healthy children and their mothers.

Methods

We screened for CMV IgG antibodies in a convenience sample of 161 children aged 0-47 months from the Atlanta, Georgia metropolitan area, along with 32 mothers of children who screened CMV-seropositive. We assessed CMV shedding via PCR using saliva collected with oral swabs (children and mothers) and urine collected from diapers using filter paper inserts (children only).

Results

CMV IgG was present in 31% (50/161) of the children. Half (25/50) of seropositive children were shedding in at least one fluid. The proportion of seropositive children who shed in saliva was 100% (8/8) among the 4-12 month-olds, 64% (9/14) among 13-24 month-olds, and 40% (6/15) among 25-47 month-olds (P for trend = 0.003). Seropositive mothers had a lower proportion of saliva shedding (21% [6/29]) than children (P < 0.001). Among children who were shedding CMV, viral loads in saliva were significantly higher in younger children (P <0.001); on average, the saliva viral load of infants (i.e., <12 months) was approximately 300 times that of two year-olds (i.e., 24-35 months). Median CMV viral loads were similar in children's saliva and urine but were 10-50 times higher (P < 0.001) than the median viral load of the mothers' saliva. However, very high viral loads (> one million copies/mL) were only found in children's saliva (31% of those shedding); children's urine and mothers' saliva specimens all had fewer than 100,000 copies/mL. Low IgG avidity, a marker of primary infection, was associated with younger age (p = 0.03), higher viral loads in saliva (p = 0.02), and lower antibody titers (p = 0.005).

Conclusions

Young CMV seropositive children, especially those less than one year-old may present high-risk CMV exposures to pregnant women, especially via saliva, though further research is needed to see if this finding can be generalized across racial or other demographic strata.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0568-2) contains supplementary material, which is available to authorized users.

Impaired balance and neurodevelopmental disabilities among children with congenital cytomegalovirus infection

AIM

Although cytomegalovirus (CMV) is the most common congenital infection, existing research has not provided us with a full picture of how this can affect children in the future. The aim of this case-control study was to evaluate disabilities in a well-defined group of children with congenital cytomegalovirus (CMV) infection, who had been fitted with cochlear implants because of severe hearing impairment.

METHODS

A multidisciplinary team assessed 26 children with congenital CMV infection for balance difficulties, neurodevelopmental disabilities and language and visual impairment. We also included a control group of 13 children with severe hearing impairment due to connexin 26 mutations.

RESULTS

The majority of the children with congenital CMV infection (88%) displayed balance disturbances, including walking at a later age, but there were no cases in the control group. The CMV group also displayed frequent neurodevelopmental disabilities and feeding difficulties.

CONCLUSION

Congenital CMV infection affects the general development of the brain and gives rise to a complex pattern of difficulties. Identifying comorbid conditions is very important, as children with associated difficulties and disabilities need more support than children with just hearing impairment. Congenital CMV infection needs to be considered in children with hearing impairment and/or balance disturbance and/or neurodevelopmental disabilities.

Fatal pneumonia following maternal HSV-1 viraemia in late pregnancy

Neonatal Herpes simplex virus (HSV) pneumonia without apparent accompanying disseminated infection is a rare condition. We describe a case of neonatal pneumonia following maternal HSV type 1 viraemia in late pregnancy. A review of the literature shows that cases of HSV presenting as pneumonia in the first week of life are the most severe form of neonatal HSV.

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.

Development of a novel single tube nested PCR for enhanced detection of cytomegalovirus DNA from dried blood spots

Newborn screening for congenital cytomegalovirus (CCMV) using dried blood spots (DBS) has been proposed because many developed countries have DBS screening programmes in place for other diseases. The aim of this study was to develop a rapid, single tube nested polymerase chain reaction (PCR) method for enhanced detection of CMV from DBS compared to existing (single target) real time PCRs. The new method was compared with existing real time PCRs for sensitivity and specificity. Overall sensitivity of the single target PCR assays in both asymptomatic and symptomatic infants with laboratory confirmed congenital CMV was 69% (CMV PCR or culture positive before day 21 of life). In contrast, the single tube nested assay had an increased sensitivity of 81% with100% specificity. Overall the assay detected CMV from a DBS equivalent to an original blood sample which contained 500IU/ml. In conclusion this single tube nested methodology allows simultaneous amplification and detection of CMV DNA in 1.5h removing the associated contamination risk of a two step nested PCR. Owing to its increased sensitivity, it has the potential to be used as a screening assay and ultimately allow early identification and intervention for children with congenital CMV.

How to use... neonatal TORCH testing

Toxoplasma gondii, rubella, cytomegalovirus and herpes simplex virus have in common that they can cause congenital (TORCH) infection, leading to fetal and neonatal morbidity and mortality. During the last decades, TORCH screening, which is generally considered to be single serum testing, has been increasingly used inappropriately and questions have been raised concerning the indications and cost-effectiveness of TORCH testing. The problems of TORCH screening lie in requesting the screening for the wrong indications, wrong interpretation of the single serum results and in case there is a good indication for diagnosis of congenital infection, sending in the wrong materials. This review provides an overview of the pathogenesis, epidemiology and clinical consequences of congenital TORCH infections and discusses the indications for, and interpretation of, TORCH screens.

Etiology and audiological outcomes at 3 years for 364 children in Australia

Hearing loss is an etiologically heterogeneous trait with differences in the age of onset, severity and site of lesion. It is caused by a combination of genetic and/or environmental factors. A longitudinal study to examine the efficacy of early intervention for improving child outcomes is ongoing in Australia. To determine the cause of hearing loss in these children we undertook molecular testing of perinatal “Guthrie” blood spots of children whose hearing loss was either detected via newborn hearing screening or detected later in infancy. We analyzed the GJB2 and SLC26A4 genes for the presence of mutations, screened for the mitochondrial DNA (mtDNA) A1555G mutation, and screened for congenital CMV infection in DNA isolated from dried newborn blood spots. Results were obtained from 364 children. We established etiology for 60% of children. One or two known GJB2 mutations were present in 82 children. Twenty-four children had one or two known SLC26A4 mutations. GJB2 or SLC26A4 changes with unknown consequences on hearing were found in 32 children. The A1555G mutation was found in one child, and CMV infection was detected in 28 children. Auditory neuropathy spectrum disorder was confirmed in 26 children whose DNA evaluations were negative. A secondary objective was to investigate the relationship between etiology and audiological outcomes over the first 3 years of life. Regression analysis was used to investigate the relationship between hearing levels and etiology. Data analysis does not support the existence of differential effects of etiology on degree of hearing loss or on progressiveness of hearing loss.

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 is the second most frequent cause of bilateral hearing loss in young French children

OBJECTIVE

To estimate the prevalence of congenital cytomegalovirus (cCMV) among causes of bilateral hearing loss in young French children.

STUDY DESIGN

Children <3 years old with hearing loss were prospectively included at their first visit to a referral center. Cytomegalovirus polymerase chain reaction was performed on dried blood spots from Guthrie cards. Medical records were reviewed.

RESULTS

One hundred children with bilateral hearing loss were included at a median age of 15 months; the prevalence of cCMV was 8% (8/100) (95% CI, 2.7%-13.3%) in this population and 15.4% (8/52) in the subpopulation of children with profound bilateral hearing loss. Delayed neurodevelopment and brain abnormalities on computed tomography scan were found more often in children with cCMV than in children with hearing loss without cCMV (P = .027, P = .005). In 6 of 8 cCMV cases, cCMV infection had not been diagnosed before the study.

CONCLUSIONS

In a comprehensive study of the causes of bilateral hearing loss in young French children, cCMV is the second most frequent cause of hearing loss after connexin mutations. It underlines that a majority of French children with hearing loss and cCMV are not diagnosed early and therefore may not benefit from early intervention including the possibility of neonatal antiviral treatment. These results make the case for promoting systematic cytomegalovirus screening in neonates with confirmed hearing loss identified through neonatal hearing screening.

Nucleic Acid Extraction Techniques

Since thermostable Taq DNA polymerase was discovered in 1987, nucleic acid amplification techniques have made great strides and contributed greatly to progress in the life sciences. These techniques were introduced into the clinical laboratory and have produced great changes in diagnostic tools and tests. In particular, there have been many innovative molecular testing developments in the field of diagnostic microbiology.

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.

Real-time PCR-based testing of saliva for cytomegalovirus at birth

Evaluation of: Boppana SB, Ross SA, Shimamura M et al. Saliva polymerase-chain-reaction assay for cytomegalovirus screening in newborns. N. Engl. J. Med. 364, 2111-2118 (2011). Cytomegalovirus (CMV) commonly causes congenital infection. As such, CMV is a prominent etiology for nongenetic sensori-neural hearing loss. However, screening examination in the perinatal and early infant period fails to identify most children at risk for CMV-produced hearing loss because of the absence of symptoms early in life. Furthermore, generalized screening for congenital CMV infection has yet to be implemented. Currently, newborns are tested via means of a rapid saliva culture but large-scale automation of this test would be difficult. Fortunately, newer potential replacement tests have been created. An important advance includes testing newborns via means of PCR using liquid or dried saliva samples. In a large-scale, prospective, multi-institutional study both types of salivary samples were compared with the gold standard of saliva culture. Of the 34,989 neonates tested, 0.5% or 177 samples tested positive for CMV. Testing of both liquid and dried saliva were sensitive (>97%) as well as specific (>98%) when measured against CMV culture. PCR testing of dried saliva has the potential benefit of adapting to generalized screening of neonates for congenital CMV infection. The advantages of early detection, intervention for and treatment of cases that are not clinically apparent needs to be carefully evaluated before proposing universal newborn screening for CMV infection as a valuable public health strategy.

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.

Differentiating inherited human herpesvirus type 6 genome from primary human herpesvirus type 6 infection by means of dried blood spot from the newborn screening card

To differentiate active human herpesvirus type 6 (HHV-6) infection from inherited HHV-6 (iHHV-6), we analyzed dried blood spots from archived newborn screening cards in 3 patients with high HHV-6 DNA copy numbers. Two patients were positive for HHV-6 DNA as neonates suggesting iHHV-6. In 1 patient, the absence of HHV-6 DNA excluded iHHV-6.

Prevalence of congenital cytomegalovirus infection in Slovenia: a study on 2,841 newborns

Human cytomegalovirus (CMV) is the most frequent cause of congenital infection in humans. In the first prevalence study of congenital CMV infection in Eastern and Central Europe, all neonates born in a 22-month period in two Slovenian maternity units (total of 2,841 newborns) were screened prospectively for congenital CMV infection by a real-time polymerase chain reaction (PCR) in urine. In all newborns with positive screening results, plasma and dried blood spots (DBS) collected at birth were tested additionally for CMV DNA. Congenital CMV infection was confirmed by virus isolation from a urine sample collected within the first 2 weeks of life. Congenital CMV infection was identified in four out of 2,841 newborns tested (incidence 0.14%; 95% CI, 0.05-0.39%). In four newborns with confirmed congenital infection, the concentration of CMV DNA in urine ranged from 4.68 to 8.18 log(10)  copies/ml, all four newborns had detectable CMV DNA in plasma taken at birth (1.26-3.34 log(10)  copies/ml) and two out of four had detectable CMV DNA in DBS collected during newborn metabolic screening. None of the four newborns with confirmed congenital CMV infection was symptomatic. The study showed that the prevalence of congenital CMV infection at birth in Slovenia is among the lowest in the world and that CMV DNA PCR testing of urine is a suitable and affordable real-time screening strategy for congenital CMV infection. If it is performed in 24 mini-pools, the cost of screening is 1.4 €/newborn and the cost of detecting a single newborn with congenital CMV infection 1,000 €.