Improving surveillance of infectious diseases in child daycare settings: insights from a pilot study in the Netherlands.

Child daycare centres (DCCs) are high-risk settings for infectious disease transmission. Although Dutch DCCs are legally required to report unusually high numbers of infections to Public Health Services (PHS), underreporting is common. Our pilot study aims to enhance DCC surveillance using a simple paper-based syndromic tool and wastewater monitoring. Large DCCs in the Dutch PHS-region Zuid-Holland Zuid were invited. During 16 weeks in summer and winter, DCCs recorded weekly counts of children (0-4 years) and staff with respiratory, gastrointestinal and skin infections using tally sheets. Incidence rates/100 persons/week were calculated and compared between seasons (Wilcoxon signed-rank test; DCC-level). In parallel, feasibility of local wastewater surveillance was assessed in stand-alone DCCs through sewer map review, on-site inspection and dye testing to identify DCC-specific sampling points, with planned analysis for parvovirus B19, norovirus and respiratory syncytial virus. Twenty-six DCCs participated in summer and 23 in winter. DCCs reported 7 mandatory outbreak notifications in summer and 4 in winter. Tally sheets showed a higher incidence in winter than in summer (20.1 vs. 8.8/100 persons/week; p < 0.001). Respiratory infections predominated in summer and winter. Ten DCCs were assessed for wastewater surveillance feasibility. Due to infrastructural constraints, no DCC was suitable and wastewater surveillance was not performed. In our pilot study, paper-based syndromic surveillance provided insights into infectious disease incidences in DCCs beyond mandatory notifications, but was perceived as burdensome, whereas wastewater surveillance proved infeasible. Future DCCs surveillance should prioritize low-burden, scalable systems independent of healthcare-seeking, testing and reporting behaviour.