Screening for congenital cytomegalovirus infection using newborn urine samples collected on filter paper: feasibility and outcomes from a multicentre study

Abstract

Background

As congenital cytomegalovirus (CMV) infection causes significant clinical consequences not only at birth but also later as neurological sequelae, it is critical to establish a strategy for screening congenitally infected newborns. Previous studies have identified an insufficient sensitivity in screening methods based on the use of dried blood spots (DBSs).

Objectives

To evaluate the feasibility of the authors' recently developed method for large-scale screening for congenital CMV infection and to identify risk factors for congenital infection.

Methods

More than 21 000 newborns were enrolled at 25 sites in six geographically separate areas of Japan. Urine was collected onto filter cards placed in the diapers, which were then analysed by quantitative PCR using the filter disc directly as a template. Clinical and physical findings of the newborns were extracted from their medical records. CMV strains from the cases and their siblings were genetically compared. Viral loads in DBSs obtained from some of the cases were compared with those in the urine filters.

Results

Congenital CMV infection was identified in 0.31% (95% CI 0.24% to 0.39%) of the newborns, and 30% of the cases (20/66) had typical clinical manifestations and/or showed abnormalities in brain images at birth. Although the positive predictive value of our screening was 94%, the lack of any comparison with a gold standard assay prevented calculation of the negative predictive value. Almost two-thirds of the cases had siblings, a significantly higher frequency than for uninfected newborns. Most of the cases (21/25) excreted CMV strains identical to those of their siblings. CMV DNA was undetectable in three out of 12 retrievable DBS specimens.

Conclusions

Implementation of an effective large-scale screening programme for congenital CMV infection is feasible. Siblings are the major risk factor for congenital CMV infection, which emphasises the need for education of mothers-to-be as well as vaccine development.

Article summary

Article focus

• It is critical to establish a strategy for screening newborns infected congenitally with cytomegalovirus (CMV), as they are at risk for the development of neurological sequelea. However, because of the insufficient sensitivity of newborn CMV screening based on dried blood spots, the feasibility of an alternative approach using urine specimens needs to be evaluated.

• Not only population-based epidemiological studies, but also prospective molecular studies, are necessary to clarify the transmission routes of congenital CMV infection.

Key messages

• Collection of urine specimens onto filter cards placed in the diapers made large-scale screening for congenital CMV infection feasible and effective without compromising detection sensitivity.

• One out of every 300 newborns is congenitally infected with CMV, and 30% of the cases were symptomatic in the society where the CMVseroprevalence is 70%, indicating that the frequency of congenital CMV infections is a medical problem of the same level as Down's syndrome.

• Our direct molecular evidence indicates that siblings are the major risk for congenital CMV infection.

Strengths and limitations of this study

• This multicentre large-scale screening study demonstrates that our urine-filter-based method is robust and reliable. However, the lack of any comparison with a gold standard assay prevented the determination of the exact frequency of false-negative results.

• Serological studies on mothers need to be combined with newborn screening to confirm whether transmission predominantly occurs via maternal primary infection.