Universal and Expanded Screening Strategy for Congenital Cytomegalovirus Infection: Is Pool Testing by a Rapid Molecular Test in Saliva a New Choice in Developing Countries?

BACKGROUND: Several screening strategies for identifying congenital CMV (cCMV) have been proposed; however, the optimal solution has yet to be determined. We aimed to determine the prevalence of cCMV by universal screening with saliva pool testing and to identify the clinical variables associated with a higher risk of cCMV to optimize an expanded screening strategy. METHODS: We carried out a prospective universal cCMV screening (September/2022 to August/2023) of 2186 newborns, analyzing saliva samples in pools of five (Alethia-LAMP-CMV®) and then performed confirmatory urine CMV RT-PCR. Infants with risk factors (small for gestational age, failed hearing screening, HIV-exposed, born to immunosuppressed mothers, or <1000 g birth weight) underwent expanded screening. Multivariate analyses were used to assess the association with maternal/neonatal variables. RESULTS: We identified 10 infants with cCMV (prevalence: 0.46%, 95% CI 0.22-0.84), with significantly higher rates (2.1%, 95% CI 0.58-5.3) in the high-risk group (p = 0.04). False positives occurred in 0.09% of cases. No significant differences in maternal/neonatal characteristics were observed, except for a higher prevalence among infants born to non-Chilean mothers (p = 0.034), notably those born to Haitian mothers (1.5%, 95% CI 0.31-4.34), who had higher odds of cCMV (OR 6.82, 95% CI 1.23-37.9, p = 0.04). Incorporating maternal nationality improved predictive accuracy (AUC: 0.65 to 0.83). CONCLUSIONS: For low-prevalence diseases such as cCMV, universal screening with pool testing in saliva represents an optimal and cost-effective approach to enhance diagnosis in asymptomatic patients. An expanded screening strategy considering maternal nationality could be beneficial in resource-limited settings.

Optimizing congenital cytomegalovirus detection by pool testing in saliva by a rapid molecular test.

Universal congenital cytomegalovirus (cCMV) screening in saliva is increasingly recommended. The aim of our study was to correlate the performance of a point-of-care rapid molecular test with CMV real time PCR (CMV RT-PCR) detection, using saliva pool-testing in newborns under a universal screening strategy. Saliva swabs were prospectively collected from newborns < 21 days old and tested by Alethia-LAMP-CMV assay in pools of 5 samples. In positive pools, subjects were tested individually and by saliva and urine CMV RT-PCR. A subset of negative pools were studied with both techniques and viral loads in whole blood were determined in positive patients. From 1,642 newborns included in 328 pools, 8 were confirmed by urine CMV RT-PCR, (cCMV prevalence 0,49%). The PPA and NNA of the pooled saliva Alethia-LAMP-CMV testing were 87,5% and 99,8% with a negative and positive predictive value of 99,9% and 77,7%, respectively. Two false positives were detected (0,12%). A subset of 17 negative pools (85 samples), studied by saliva CMV RT-PCR, showed 100% concordance.  Conclusion: CMV pool-testing using a rapid molecular test in saliva proved feasible when compared to PCR gold standards. This strategy could improve cost-effectiveness for cCMV universal neonatal screening, based on the low prevalence of the infection and could be a more affordable approach in less developed regions with reduced detection capacity. What is Known: • cCMV is the most frequent congenital infection and a leading nongenetic cause of sensorineural hearing loss and brain disease. • Universal screening could allow early detection of congenitally infected infants, improving clinical outcome. • Saliva PCR is the preferred and non-invasive test for newborn cCMV screening. What is New: • The feasibility of a universal cCMV screening by pool-testing in saliva using a rapid test in pools of 5 samples. • PPA and NPA were 87,5 and 99,8% compared to CMV PCR in urine. • This strategy could be relevant specially in LMIC where detection capacity is reduced and could improve cost-effectiveness. • cCMV prevalence in our center was 0,49%.