Ospedalizzazioni associate ad arbovirosi trasmesse da Aedes in Italia nel 2023 e 2024. Un confronto dei dati di sorveglianza con le schede di dimissione ospedaliera

Hospitalizations associated with Aedes-transmitted arboviruses in Italy in 2023 and 2024: a comparison of surveillance data with hospital discharge records Introduction In Italy, dengue (DEN), zika and chikungunya (Z&C) infections are increasing. This study compared hospital admissions for these arboviruses, as reported in the Hospital Discharge Records (HDR) with those reported in the national arboviruses surveillance system in 2023-2024. Materials and methods All cases reported to the HDR system and all notifications of hospitalized cases submitted to the surveillance system during the 2023-2024 period were analyzed for DEN and Z&C cases. A descriptive frequency analysis was conducted, along with a comparison of sociodemographic variables and hospitalization characteristics. Results During the study period, the HDR system reported 541 cases DEN and 30 cases of Z&C, while the surveillance system reported 565 hospitalised DEN cases and 23 cases of Z&C. For DEN, both systems showed an increase in cases in 2024 (61.2% for HDR vs 61.4% for the surveillance system), a peak in the third quarter (46.2% vs 48.4%), a slight male predominance (53.2% vs 52.0%), and similar median age (37 vs 39 years). For Z&C, temporal peaks differed (60% of cases occurred in the third quarter vs 50% in the fourth). Sex distribution was similar (50.0% males vs 52.0%), whereas median age differed (63 vs 43 years). Length of hospital stay was comparable (DEN: 5 days; Z&C: 6 days), but Intensive Care Unit admissions (0.9% vs 6.7%) and mortality (0.9% vs 6.7%) were higher among Z&C cases. Conclusions The two systems show good concordance for DEN, but there are notable discrepancies for Z&C, particularly with regard to age and seasonality. Integrating both data sources improves the quality of the data, identifies undernotification and enhances the estimation of the clinical impact of arboviruses. Key words: arboviruses; surveillance; hospitalization