Human cytomegalovirus quantification in toddlers saliva from day care centers and emergency unit: a feasibility study

Cytomegalovirus (CMV) infection is the most important cause of congenital viral infection in developed countries. In utero transmission occurs at higher rates in seronegative women during primary infection, especially those in contact with young children in day-care centers (DCC). Nevertheless data on variability of CMV excretion among children in French DCCs are lacking, and are important for public health planning.

Our main objective was to assess the feasibility of a salivary sample in DCCs in order to study CMV excretion among toddlers. Our secondary aims were to assess prevalence of CMV excretion in children attending Hospital Emergency Unit (EU) in comparison with various types of DCCs and to validate the analytical chain for collected specimens.

Excretion of CMV in saliva was quantified using a real-time PCR assay in children aged from 3 months to 6 years old in EU and in DCC, with gB, gH and gN genotypes determined in infected children. Salivary sampling was performed using small sponges placed into a DNA conservation medium. Socio cultural and medical information were collected from attending parents.

A total of 625 children were included, with 256 from six DCCs and 369 from one EU. In DCCs, the acceptability of the procedure was 87.3% (95%CI 78.5-96.2) amongst parents and children, and in the EU, acceptability was higher at 97.6% (95%CI 95.5-98.9). CMV shedding overall prevalence was 21.7% (95%CI 17.6-26.2), with CMV shedding prevalence in DCCs of 51.9% (95%CI 22.8-81.1).

We validated the feasibility and acceptability of measuring CMV shedding in the saliva of French toddlers. The discrepancy between CMV infection rates in day care centers and in the general population (as sampled in the EU) indicates the need for a further study to determine risk factors and shedding levels in the DCC population.