The risk of cytomegalovirus infection in daycare workers: a systematic review and meta-analysis

Purpose The primary aim of this review was to summarize the evidence on the relationship between being a daycare worker working with children and the possible increased risk of cytomegalovirus infection. Methods We searched the Medline and Embase databases using search strings defined according to the population, exposure, comparison, and outcomes (PECO) applicable to our research questions in order to find studies published since 2000. Two independent reviewers evaluated the search hits using predefined inclusion and exclusion criteria. A manual search was performed to identify additional relevant literature. We extracted the resulting studies and assessed them in eight domains of bias. The pooled CMV seroprevalence for daycare workers compared to the general population was calculated. Results After evaluating the 6879 records, six methodologically adequate studies were identified: five cross-sectional studies and one cohort study. The pooled seroprevalence of daycare workers was 59.3% (95% CI 47.6-70.9). The four studies investigating risk of infection indicated an increased seroprevalence for daycare workers compared to a reference population (prevalence ratio, PR = 1.54, 95% CI 1.33-1.77). No study evaluated CMV seroconversions for daycare workers. Conclusions Our findings suggest a higher CMV seroprevalence for daycare workers compared to the general population. Notwithstanding the need for longitudinal and intervention studies, preventative efforts are needed. A pooled PR of 1.54 is compatible with a doubled seroconversion risk corresponding to a vocational probability of 50% if the substantial underestimation of the actual occupational seroconversion risk by prevalence-based estimators is considered.