Early Detection of Dysentery Outbreaks by Cumulative Sum Method Based on National Surveillance System Data in 1393-1396

Correct and timely detection of the outbreaks of diseases with a short incubation period is of great importance in the health system. The aim of this study was to determine the detection of dysentery outbreaks using the cumulative sum method.

This time series study was conducted using the data of the National Surveillance System between 2014 and 2017. The outbreak alert threshold of each season and province was determined separately using the average of three years (1393 to 1395) in the same season and province. The dysentery outbreak in each season was exclusively predicted for Isfahan, Khuzestan, and Hamadan provinces in 2017 using the CUSUM method.

In Isfahan Province, the outbreak alert was higher in the spring and summer and lower in the autumn and winter using the current method compared to the CUSUM method. For Khuzestan Province, the current outbreak alert was significantly higher in all seasons compared to the CUSUM method, while the current outbreak alert was lower than the alert predicted by the CUSUM method in Hamadan Province in all the seasons.

Compared to constant threshold-based methods, using the CUSUM method seems to be a better way for reporting outbreaks, especially in areas with a high incidence.