Objective: To understand the effectiveness of China Infectious Disease Automated-alert and Response System (CIDARS) for outbreak detection at the regional level.
Methods: Two counties in Hunan province (Yuelu and Shuangfeng county) and two counties in Yunnan province (Xishan and Gejiu county) were chosen as the study areas. Data from CIDARS were analyzed on the following items: reported cases, warning signals, the time interval of signal response feedback, way of signal verification, outcome of signal verification and field investigation, from July 1, 2008 to June 30, 2010.
Results: In total, 12 346 cases from 28 kinds of diseases were reported, and 2096 signals of 19 diseases were generated by the system, with an average of 4.94 signals per county per week. The median of time interval on signal verification feedback was 0.70 hours (P(25)-P(75): 0.06 - 1.29 h) and the main way of signal preliminary verification was through the review of surveillance data (account for 63.07%). Among all the signals, 34 of them (1.62%) were considered to be related to suspected events via the preliminary verification at the local level. Big differences were found to have existed on the proportion of signals related to the suspected events of the total signals among the four counties, with Shuangfeng county as 4.71%, Yuelu county as 1.88%, Gejiu county as 0.95% and Xishan county as 0.58%. After an indepth study on the fields of suspected events, 12 outbreaks were finally confirmed, including 5 on rubella, 4 on mumps, 2 on influenza and 1 on typhoid fever.
Conclusion: CIDARS could be used to assist the local public health institutions on early detection of possible outbreaks at the early stage. However, the effectiveness was different depending on the regions and diseases.