Performance of automatic early warning system of communicable diseases in Shaanxi, 2008-2012

Objective To evaluate the performance of the automatic early warning system of communicable diseases in Shaanxi province during 2008-2012 and provide scientific evidence for the improvement of the system. Methods Descriptive epidemiological analysis was conducted on the results generated by the automatic early warning system during this period. Results Totally 51245 warning signals of disease outbreaks in Shaanxi were generated, involving 30 kinds of communicable diseases, the positive rate of early warning was 0.05%. A positive correlation between the number of signals and the case numbers of notifiable communicable diseases was observed in all areas in Shaanxi. The generation of signals had obvious seasonality, the peaks were during at summer and winter. The major diseases involved included other infectious diarrhea diseases, mumps, hand foot and mouth disease, dysentery and measles, accounting for 81.77% of total signals (41 905/51 245). The annual response rate was 86.11%, 84.44%, 83.17%, 99.97% and 99.97% respectively. The verifying of the signals was mainly through surveillance data analysis, accounting for 57.39%. The response time ranged from 0.84 hours to 2.27 hours. Conclusion The performance of the communicable disease automatic early warning system was stable, which played an important role in the early detection of the index case and disease outbreaks. However, further improvement should be made on the early warning system, including choosing more appropriate early warning thresholds.