Evaluation of mandatory case-based reporting system for varicella in the prevaccine era

Varicella is a mandatory reportable disease in Slovenia but it is not notifiable in most European countries. The aim of the study was to explore the completeness of mandatory varicella reporting in Slovenia. Data were extracted from three electronic datasets, including: mandatory notifiable communicable diseases dataset (SURVIVAL), health statistics dataset - consultations in primary care (ZUBSTAT), and health statistics dataset --hospitalizations (BOLOB). Age- and sex-specific reporting rates were compared during the period 1997-2006. During the ten-year period studied 168,089 cases were recorded via ZUBSTAT, and 128,222 cases by SURVIVAL. On average 76.2% (range: 62.9%-94.9%) were notified. In both datasets, the notified incidence of varicella was highest for preschool children, with a downward shift in age at contracting varicella. The percentage of notified cases decreased with increasing age. The number of hospitalized cases was low for BOLOB and SURVIVAL. On average 74% of hospitalized cases were reported. The mandatory notification system in Slovenia provides enough information to survey age/sex-specific varicella trends in the prevaccine era.