Pooled saliva tests for congenital cytomegalovirus (cCMV) infection are both accurate and cost-efficient, potentially transforming the implementation of universal cCMV screening, suggests a study presented at IDWeek 2024.

The “[w]ide feasibility and benefits of pooled-saliva testing as an efficient, cost-sparing, and sensitive approach support its widespread implementation,” said presenting author Dr Dana Wolf, Hadassah-Hebrew University Medical Center, Jerusalem Israel.

This prospective study was conducted in two hospitals in Jerusalem from April 2022 until April 2024. Wolf and colleagues collected saliva samples of all newborns with parental consent and tested these for cCMV in 8-sample pools. Urine testing was carried out to confirm positive saliva results.

A total of 32,413 infants (94.4 percent of al live newborns) underwent screening for cCMV using the pooled approach, which proved to be highly efficient. Each PCR test covered an average of six newborns during the first 13 months of the study, reducing the number of required saliva tests by as much as 83 percent. [IDWeek 2024, abstract 380]

“PCR loss of sensitivity was minor, in accordance with the theoretical prediction for an 8-sample pool,” Wolf said.

Of the infants, 123 tested positive for cCMV, representing a birth prevalence of 3.8 per 1,000. Notably, more than half (n=71, 57.7 percent) of newborns with cCMV identified by universal screening showed no symptoms at birth and would have been missed by targeted screening. Ten infants (14.1 percent) had symptomatic cCMV, of which seven were moderate-to-severe in severity.

This pooled approach can be easily integrated in any medium or large medical laboratory, according to Wolf, noting the high parental acceptance of cCMV screening.

Early diagnosis

Furthermore, these findings stress the clinical implications toward early diagnosis, monitoring, and treatment of cCMV in infants, as well as show the true population prevalence, burden, risk factors, and long-term clinical outcomes of this infectious disease, said Wolf. The results also function as “real-life evidence” for the development of a vaccine in the future.

“Beyond the clinical implications toward early diagnosis, monitoring, and treatment of cCMV, data derived from the implemented universal screening will serve to define the burden, risk factors, and long-term clinical outcomes of cCMV,” Wolf said.

A common intrauterine infection, cCMV can result in neurodevelopmental disabilities and hearing loss, which can appear at birth or develop later during childhood.

At present, many centres conduct targeted screening of cCMV via PCR testing of saliva samples, but targeted screening of high-risk newborns misses most infants with cCMV who show no symptoms at birth but are at risk for late-onset sequelae.

“Thus, universal newborn screening of cCMV has been increasingly advocated,” Wolf said.

“In the absence of a high-throughput screening test that can identify all infected neonates, the development of an accurate and efficient testing strategy for universal cCMV screening has remained an ongoing challenge,” she added.