[Discussion on five methods used for the determination of temporal clustering on infectious diseases].

To demonstrate and evaluate five different methods in the determination of temporal clustering on infectious diseases. The incidence rates of bacillary dysentery in Jinshui district, Zhengzhou city, Henan province from 2008 to 2010 were analyzed by 5 different methods-Cluster Analysis, Runs Test, Negative Binomial Distribution, Circular Distribution and Concentration Ratio. Through Cluster Analysis, data showed that the epidemic period was from May to Sept. with August as the peak. Runs Test confirmed a cluster of month-incidence in 2008 and 2009 (P < 0.05) and a random distribution in 2010. The Concentration Ratio showed a weakened seasonal incidence cluster to a certain extent by M from 2008 to 2010. The Circular Distribution demonstrated an inclining cluster of time (P < 0.01) and it was on July 11(th) and 29(th), as well on August 24(th) in 2008, 2009 and 2010. In terms of day-incidence, the Negative Binomial Distribution presented a cluster in 2008 and 2010, but with no significant difference in 2009. The five above said methods could flexibly be used in determining the temporal clustering of infectious disease at different occasions.