Evaluation of the National Notifiable Disease Surveillance System in Taiwan: an example of varicella reporting.

Despite the mandatory reporting by laws, the incompleteness of notifiable infectious disease reporting is well-documented in many countries for various diseases. The purpose of this study is to investigate the completeness of varicella reporting in Taiwan. Annual reports of National Notifiable Disease Surveillance System in Taiwan were compared to the annual outpatient claims of National Health Insurance (NHI) in the years of 2000, 2001, and 2002. Age and area-specific reporting rates of varicella were calculated by dividing the respective reported cases by the number of incidence cases. The reporting rate was the highest in aged 0 year in all years, followed by the 20-29- and 30-39-year groups. The reporting rate in each age group increased gradually during the study period. Other than Taipei City, the reporting rates in all regions were below 9% during this period. This study suggested that varicella reporting rate is very low in Taiwan. In addition, the reporting rates were inconsistent in 2000-2002, making the estimation of prevalence and vaccine efficacy using data from the National Notifiable Disease Surveillance System almost impossible. This study indicated that the physicians in Taiwan should improve their knowledge and attitude toward notifiable infectious diseases.