Congenital cytomegalovirus infection is a significant cause of ...

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doi:10.1111/jpc.12776

ORIGINAL ARTICLE

Congenital cytomegalovirus infection is a significant cause of moderate to profound sensorineural hearing loss in Queensland children Christopher J Toumpas,1,2,3 Julia Clark,4,5 Alison Harris,4,5 Rachael Beswick6 and Clare B Nourse4,5 1 Department of Paediatrics, Mater Children’s Hospital, 2Department of Paediatrics, Greenslopes Private Hospital, 3School of Medicine, University of Queensland, 4Department of Paediatrics, Lady Cilento Children’s Hospital, 5Department of Paediatrics, University of Queensland, South Brisbane, and 6Health Services Support Agency, Brisbane, Queensland, Australia

Aim: To investigate the proportion of children with moderate to profound hearing loss who have congenital cytomegalovirus (cCMV) infection. Method: Retrospective analysis of CMV dried blood spot (DBS) polymerase chain reaction (PCR) in children with moderate to profound hearing impairment referred to tertiary referral centres in Queensland. Participants were under 18 years old with no readily identified cause of hearing impairment, between 2008 and 2011. The primary outcome measure was DBS CMV PCR. Other outcome measures for cases referred to the Childhood Hearing Clinic (CHC) at the Mater Children’s Hospital were level of hearing impairment and the neonatal hearing screen result. Results: Of DBS CMV PCR testing for 106 children at the CHC for 2008 to 2011 inclusive, nine (8.5%) were positive (five with bilateral hearing impairment, four with unilateral hearing impairment). The prevalence of cCMV infection in children with moderate to profound hearing impairment was 8.4%, consistent with the statewide rate of 9.4% for 2008 to mid-2011. Conclusion: cCMV is a significant cause of hearing impairment in Queensland children. Investigation for cCMV by retrospective DBS CMV PCR should be part of the routine investigation of all babies and young children with hearing impairment. However early diagnosis is preferable and could be achieved by routine early screening of all newborns with hearing impairment for CMV before 3 weeks of age. The healthy hearing screening programme is a routine part of neonatal care. Enhancing the integration of screening for cCMV may reduce the current delays in diagnosis and should be evaluated.

What is already known on this topic

What this paper adds

1 Congenital cytomegalovirus (cCMV) is the leading non-genetic cause of moderate to profound sensorineural hearing loss. 2 The contribution of cCMV to hearing impairment in the Australian context has not been established. 3 Therapeutic interventions to prevent progressive hearing loss in newborns with cCMV are now available and if used, should be commenced in the first 4 weeks of life.

1 This study suggests that at least 8–10% of hearing-impaired babies in Queensland have cCMV as the underlying cause. 2 This is comparable to international findings and confirms that cCMV is a significant cause of hearing impairment in the Queensland population. 3 Screening for cCMV during the neonatal period may reduce the current delays in diagnosis and should be evaluated.

Hearing impairment is a common and important sequela of congenital cytomegalovirus (cCMV) occurring in 10–15% of infections.1,2 cCMV infection is the leading non-genetic cause of hearing impairment responsible for 15–20% of moderate to profound sensorineural hearing loss (SNHL).3,4 Therapeutic interventions to prevent progressive hearing loss in newborns with cCMV, such as treatment with ganciclovir or its oral prodrug valganciclovir, are now available and if used, should be commenced in the first 4 weeks of life.5,6 It is thereCorrespondence: Dr Christopher J Toumpas, Department of Paediatrics, Suite 2D, G10 Building, Greenslopes Private Hospital, Brisbane, Qld, 4120, Australia. Fax: +07 3177 2001; email: ctoumpas@greenslopespaediatrics .com.au Conflict of interest: The authors declare no conflict of interests. Accepted for publication 11 October 2014.

fore important to identify children with hearing loss due to cCMV as soon after birth as possible. The contribution of cCMV to hearing impairment in the Australian context has not been established.7 This study aimed to describe the prevalence of cCMV in children with moderate to profound hearing loss, providing data on the burden of disease and informing health economic modelling for cCMV screening.

Methods Data on all children presenting to tertiary centres in Queensland with moderate to profound hearing impairment were collected retrospectively from two databases maintained at the Mater Children’s Hospital, a tertiary paediatric centre in Brisbane, Queensland: 1 The clinical database on children with moderate to profound hearing impairment attending a paediatric hearing clinic

Journal of Paediatrics and Child Health 51 (2015) 541–544 © 2014 The Authors Journal of Paediatrics and Child Health © 2014 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

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(currently called the Childhood Hearing Clinic or CHC) at the Mater Children’s Hospital between 2008 and 2011 inclusive. 2 The Healthy Hearing Program’s (HHP) database and patient records from 2008 to mid-2011. This database is maintained by audiologists as part of the Healthy Hearing Program using the eScreenerPlus (eSP) software, version 4.2 (2003–2006) (http://www.oz-systems.com). The HHP eSP database also contains data for all children screened through the Queensland HHP, thus allowing a statewide calculation of the rate of positive dried blood spot (DBS) CMV polymerase chain reaction (PCR) tests. Hearing impairment was the only diagnosed pathology in all cases. Cases with readily identified causes of hearing impairment were excluded and identified using local medical guidelines, which recommend assessments by an ear, nose and throat (ENT) surgeon, paediatrician, geneticist and an ophthalmologist as well as an investigation protocol, which includes imaging, genetic testing, metabolic screening and serology for congenital infections (full list of investigations is available in the online supplement). The DBS CMV PCR is routinely performed locally as part of the investigation of SNHL and is recorded in the two databases and records. The CHC database was used in this study in order to provide clinical details of the hearing impairment in a subset of patients presenting to the Mater Children’s Hospital. The HHP database was used to collect data on the larger population of all Queensland children presenting with hearing impairment. Details obtained for all cases included test dates, age when investigated and DBS CMV PCR results. Further clinical details available specifically from the CHC database included the level of hearing impairment and the results of the neonatal hearing screen. The result of the neonatal hearing screen is included because children with SNHL may either be referred to tertiary centres for failing the neonatal screen or may present at a later age. Congenital CMV infection was defined as a positive urine CMV PCR test within the first 3 weeks of life or a positive DBS CMV PCR test. Hearing impairment was classified as moderate (loss of 40–65 dB), severe (65–95 dB); or profound (if the threshold was 95

dB). The Queensland neonatal hearing screening programme uses automated auditory brainstem response (AABR) for neonatal screening. Results were stored in the eSP and CHC databases as a pass or refer for further assessment. CMV PCR testing was performed by Pathology Queensland (Clinical and Statewide Services Laboratory) using a standard diagnostic Nucleic Acid Amplification (NAA) assay.8 Samples were extracted from the DBS and placed into labelled Eppendorf tubes, treated with tissue lysis and placed in a 55°C heating block for at least 1 h and then pulse spun. The laboratory used CMV oligonucleotides described in a previously published paper to develop a TaqMan probe for NAA using the Rotor-Gene PCR machine.9 This method was previously described to be highly sensitive in immunosuppressed children,9 but is not necessarily sensitive when used to test newborn DBS for cCMV.10 Ethics approval was granted by the Mater Human Research and Ethics Committee. There was no funding required for this study. The authors have full access to all of the data used in this study.

Results A total of 118 children were referred to the CHC from 2008 to 2011 inclusive with moderate to profound hearing impairment. Twelve children were excluded as they already had an identified cause or diagnosis for their hearing impairment. Nine of the 106 children had a positive DBS CMV PCR test (8.4%). The HHP screened 213 206 Queensland children from 2008 to mid 2011. Three hundred and forty children identified with hearing on the HHP eSP database were investigated by DBS CMV PCR. Thirty-two (9.4%) were positive. Hearing impairment details and the results of the neonatal hearing screen were available only for those children identified within the CHC database (Table 1). All nine children with positive DBS CMV PCR were previously identified as having moderate to profound sensorineural hearing impairment (five had bilateral and four had unilateral hearing impairment). Seven of the nine cases were referred for further assessment to the CHC following the neonatal hearing screen through the Queensland

Table 1 Congenital CMV at the CHC: Neonatal hearing screen results, description of hearing impairment and age of patients with positive DBS CMV PCR Year

Patient number

Outcome from neonatal hearing screen

Description of hearing impairment following audiological assessment

Age at the time DBS CMV PCR was tested

2008

1 2

Refer Refer

5 weeks 10 months

2009

3

Refer

4 5 6 7

Refer Pass Refer Patient was born before routine screening Refer Refer

Bilateral, profound hearing loss Left moderate sensorineural hearing loss Right profound sensorineural hearing loss Bilateral profound sensorineural hearing loss (possible genetic cause contemplated) Bilateral, profound hearing loss Unilateral, moderate hearing loss Unilateral, profound hearing loss Bilateral, profound hearing loss (from 2 years)

2 weeks 7 months 4 months 8 years

Left profound sensorineural hearing loss Left profound sensorineural hearing loss

14 weeks 5 months

2010

2011

542

8 9

1 week

Journal of Paediatrics and Child Health 51 (2015) 541–544 © 2014 The Authors Journal of Paediatrics and Child Health © 2014 Paediatrics and Child Health Division (Royal Australasian College of Physicians)

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HHP. One case passed the neonatal hearing screen and was later referred to the CHC with a hearing impairment. The other case was 8 years old at the time of referral to the CHC – a hearing screen outcome was unavailable as the patient was born before the implementation of the HHP. Congenital CMV was not suspected or diagnosed before the investigation of SNHL at the CHC. Retrospective DBS CMV PCR was requested at the time of CHC referral, but all children were over 3 weeks old when congenital cCMV was diagnosed. Therefore, urine CMV PCR was not tested.

Discussion The proportion of CMV associated SNHL has not been established in Australia, with CMV often overlooked as a significant factor in childhood hearing impairment. In an international systematic review of 43 studies (37 retrospective studies, 3 prospective studies and 3 population-based studies) on the aetiology of bilateral SNHL in children, genetic non-syndromic causes (29.2%) and causes of unknown aetiology (37.7%) were identified as the two most common causes. None of these studies used retrospective or prospective neonatal screening for CMV infection within the newborn period to examine cCMV infection. Thus CMV was implicated in only 0.75% in the retrospective studies and 1.6% in prospective studies with no information for CMV available from any population based studies.11 Since this systematic review, several studies have evaluated the contribution of CMV to SNHL in children using retrospective analysis of DBS for CMV by PCR, similar to this study. CMV was identified by PCR on DBS in 17% (22/130) of children with SNHL >40 dB in Italy,12 in 7.3% (4/41) of children with moderate to profound SNHL in Belgium,13 in an estimated 9.9% (35/354) of children with hearing loss in Washington,14 and recently in 20% (18/91) of children with SNHL of unknown cause in Sweden.15 In Australia, a recent New South Wales study reported up to 9.6% (9/94) of hearing impaired infants assessed may be due to CMV.16 The implication of these studies is that 7% to 20% of children with SNHL have a hearing loss due to congenital infection with CMV. This study is one of the first published from Australia to estimate the proportion of infant hearing loss, which may be due to CMV, and with CMV identified by PCR on DBS in 32 of 340 hearing-impaired children tested, represents one of the largest described in terms of denominator (hearing loss) population. Our findings, suggesting that at least 8–10% of hearing-impaired babies in Queensland have cCMV as the underlying cause, fit realistically within these international parameters and confirm that cCMV is a significant cause of SNHL in the Queensland population. The variation in the severity and unilateral or bilateral nature of hearing impairment is also similar to that reported in current literature.17 Distinguishing between congenital and acquired CMV infection is difficult in children in whom testing is performed after 3 weeks of age. CMV is commonly acquired in the first weeks after birth and until recently, retrospective diagnosis of cCMV was not possible.18 However, CMV DNA can now be retrospectively detected in DBS.18 Boppana et al. (2010) reported the largest cohort screened for CMV by DBS CMV PCR testing to date.10 All births were included in their study, as opposed to a referred


sample in this study. They found a low sensitivity of 34.4% using a two-primer CMV PCR assay on DBS compared with saliva culture. This low sensitivity may be due to the method used for DNA extraction or the real-time PCR techniques, or the possibility that not all infants with cCMV infection have detectable CMV DNA in their blood at birth. As the sensitivity is so low, DBS testing cannot reliably exclude cCMV infection. However, it is the only test available for retrospective diagnosis after 3 weeks of age and with its high specificity a positive test indicates cCMV infection. Given the limitations of retrospective CMV testing, there are considerable advantages in diagnosing cCMV infection within the first 3 weeks of life.5 Universal screening has been advocated; however, a more focused approach where identifying both hearing impairment and cCMV in babies would allow the possibility of therapeutic antiviral interventions (e.g. ganciclovir/valganciclovir) may be more feasible. This study suggests that up to 10% of Queensland children with moderate to profound hearing loss may have benefited from this treatment, potentially improving their hearing outcomes or preventing deterioration. More efficient screening and earlier diagnosis of cCMV could lead to better outcomes. With the success of the newborn hearing screening programme, which identifies babies with possible hearing loss early, screening babies who have hearing impairment with CMV PCR before 3 weeks of age is a realistic proposition. It may also allow for earlier identification of deterioration of the hearing impairment associated with cCMV, which occurs after the time of the neonatal hearing screen,15 and other long-term sequelae such as neurodevelopmental delay and retinopathy.19 Saliva, urine and DBS from newborns can all be tested for CMV PCR,13,20 with both saliva and urine being highly sensitive. Although the best method of testing has yet to be confirmed, it is likely that testing of saliva will be reliable and easier to perform, given the practical difficulties of urine collection in young babies.21 There are limitations to this study both in terms of potential under and over estimating the contribution of cCMV to hearing impairment. Like all studies evaluating the contribution of CMV to SNHL in children,12–15 detecting congenital CMV infection presumes that CMV is the cause of the hearing impairment, especially in the absence of other diagnoses. However, despite careful evaluation it is possible that a proportion of the cases of hearing impairment attributed to cCMV in this study may in fact have an alternative underlying pathology. The likelihood of this occurring would be small as all cases were investigated for other genetic or syndromic causes. On the other hand, it is quite possible that some children with congenital CMV were not detected, given the low sensitivity of DBS CMV PCR. Also, 12 children from the CHC were excluded from this study as an alternative diagnosis was already identified that caused the hearing impairment. However, it is possible that the hearing impairment in these children may have been caused by congenital CMV, and not the diagnosis proposed. Statewide data on the number of children with hearing impairment that were not investigated by DBS CMV PCR were not available and may underestimate the calculated statewide rate of congenital CMV. In conclusion, this report confirms that cCMV is a significant cause of hearing impairment in Queensland children.


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Investigation for cCMV by retrospective DBS CMV PCR should be part of the routine investigation of SNHL in all babies over the age of 3 weeks and young children. However early diagnosis is preferable, and could be achieved by routine early screening of all newborns with hearing impairment for CMV before 3 weeks of age. The healthy hearing screening programme is now part of routine neonatal care. Enhancing the integration of screening for cCMV through these may reduce the current delays in diagnosis and should be evaluated.

References 1 Cheeran MC, Lokensgard JR, Schleiss MR. Neuropathogenesis of congenital cytomegalovirus infection: disease mechanisms and prospects for intervention. Clin. Microbiol. Rev. 2009; 22: 99–126. Table of Contents. PubMed PMID: 19136436. Pubmed Central PMCID: 2620634. Epub 2009/01/13.eng. 2 Yamamoto AY, Mussi-Pinhata MM, Isaac ML et al. Congenital cytomegalovirus infection as a cause of sensorineural hearing loss in a highly immune population. Pediatr. Infect. Dis. J. 2011; 30: 1043–6. PubMed PMID: 21814153. Pubmed Central PMCID: 3222783. 3 Fowler KB, Dahle AJ, Boppana SB, Pass RF. Newborn hearing screening: will children with hearing loss caused by congenital cytomegalovirus infection be missed? J. Pediatr. 1999; 135: 60–4. PubMed PMID: 10393605. Epub 1999/07/07.eng. 4 Grosse SD, Ross DS, Dollard SC. Congenital cytomegalovirus (CMV) infection as a cause of permanent bilateral hearing loss: a quantitative assessment. J. Clin. Virol. 2008; 41: 57–62. PubMed PMID: 17959414. Epub 2007/10/26.eng. 5 Nassetta L, Kimberlin D, Whitley R. Treatment of congenital cytomegalovirus infection: implications for future therapeutic strategies. J. Antimicrob. Chemother. 2009; 63: 862–7. 6 Oliver SE, Cloud GA, Sanchez PJ et al. Neurodevelopmental outcomes following ganciclovir therapy in symptomatic congenital cytomegalovirus infections involving the central nervous system. J. Clin. Virol. 2009; 46 (Suppl. 4): S22–6. PubMed PMID: 19766534. 7 McMullan BJ, Palasanthiran P, Jones CA et al. Congenital cytomegalovirus – time to diagnosis, management and clinical sequelae in Australia: opportunities for earlier identification. Med. J. Aust. 2011; 194: 625–9. PubMed PMID: 21692718. Epub 2011/06/23.eng. 8 LeCornec G. Queensland Pathology – Standard Procedure Policy – CMV TaqMan NAA Blood Spot Method. 2009. 9 Watzinger F, Suda M, Preuner S et al. Real-time quantitative PCR assays for detection and monitoring of pathogenic human viruses in immunosuppressed pediatric patients. J. Clin. Microbiol. 2004; 42: 5189–98. PubMed PMID: 15528714. Pubmed Central PMCID: 525141. Epub 2004/11/06. eng. 10 Boppana SB, Ross SA, Novak Z et al. Dried blood spot real-time polymerase chain reaction assays to screen newborns for congenital cytomegalovirus infection. JAMA 2010; 303: 1375–82. PubMed PMID: 20388893. Epub 2010/04/15. eng.

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11 Morzaria S, Westerberg BD, Kozak FK. Systematic review of the etiology of bilateral sensorineural hearing loss in children. Int. J. Pediatr. Otorhinolaryngol. 2004; 68: 1193–8. PubMed PMID: 15302152. 12 Barbi M, Binda S, Caroppo S et al. A wider role for congenital cytomegalovirus infection in sensorineural hearing loss. Pediatr. Infect. Dis. J. 2003; 22: 39–42. PubMed PMID: 12544407. Epub 2003/01/25. eng. 13 Boudewyns A, Declau F, Smets K et al. Cytomegalovirus DNA detection in Guthrie cards: role in the diagnostic work-up of childhood hearing loss. Otol. Neurotol. 2009; 30: 943–9. PubMed PMID: 19730140. Epub 2009/09/05. eng. 14 Misono S, Sie KC, Weiss NS et al. Congenital cytomegalovirus infection in pediatric hearing loss. Arch. Otolaryngol. Head Neck Surg. 2011 Jan; 137: 47–53. PubMed PMID: 21242546. Pubmed Central PMCID: 3164953. 15 Karltorp E, Hellstrom S, Lewensohn-Fuchs I et al. Congenital cytomegalovirus infection – a common cause of hearing loss of unknown aetiology. Acta Paediatr. 2012; 101: e357–62. PubMed PMID: 22519989. 16 Rawlinson W, Wilkinson M, Hall B et al. Universal Newborn Hearing Screening, Sensorineural Hearing Loss and Contribution of Congenital CMV to the Aetiology. Australasian Society of Infectious Diseases Conference; 27/03/2014; Adelaide 2014. 17 Dollard SC, Grosse SD, Ross DS. New estimates of the prevalence of neurological and sensory sequelae and mortality associated with congenital cytomegalovirus infection. Rev. Med. Virol. 2007; 17: 355–63. PubMed PMID: 17542052. Epub 2007/06/02. eng. 18 Atkinson C, Walter S, Sharland M et al. Use of stored dried blood spots for retrospective diagnosis of congenital CMV. J. Med. Virol. 2009; 81: 1394–8. PubMed PMID: 19551829. Epub 2009/06/25. eng. 19 Luck S, Sharland M. Congenital cytomegalovirus: new progress in an old disease. Paediatr Child Health (Oxford) 2009; 19: 178–84. 20 Boppana SB, Ross SA, Shimamura M et al. Saliva polymerase-chain-reaction assay for cytomegalovirus screening in newborns. N. Engl. J. Med. 2011; 364: 2111–18. PubMed PMID: 21631323. Pubmed Central PMCID: 3153859. Epub 2011/06/03. eng. 21 Williams E, Kadambari S, Berrington J et al. Targeted salivary screening for congenital CMV in the UK is feasible, acceptable and may improve hearing outcomes. Arch. Dis. Child. 2012; 97 (Suppl. 1): A31.

Supporting Information Additional Supporting Information may be found in the online version of this article at the publisher’s web-site: Appendix S1. Medical guideline used in the tertiary centres for the investigation of hearing impairment
