Performance of national communicable disease automatic early warning system in Wenzhou, Zhejiang

Objective To evaluate the performance of national communicable disease automatic early warning system in Wenzhou, Zhejiang province, and provide evidence for the improvement of the system. Methods Descriptive epidemiological analysis was conducted on the data of disease early warning in Wenzhou from 21 April 2008 to 31 December 2011 obtained from the system. Results A total of 8491 warning signals of 24 diseases were generated by the system. The response rate of the signals was 100% and the verifying rate of the signals within 24 hours was 71.75%. Eighty one signals were considered as suspected events after preliminary analysis and 7 outbreaks were finally confirmed by field investigation. The sensitivity of the system was 43.75%. Conclusion The system works on the automatic early warning of communicable diseases, but the sensitivity and positive predictive value were relatively low. More effort should be made to improve the system, such as setting the thresholds according to the local disease situation.