An analysis on time distribution of Japanese encephalitis in Baoshan by using concentration degree and circular distribution methods

Objective To understand the time distribution of Japanese encephalitis in Baoshan from 2005 to 2014. Methods Concentration degree and circular distribution methods were used to analyze the time distribution of Japanese encephalitis in Baoshan during this period. Results The concentration degree (M) was 0.818, the circular distribution (r) was 0.820 for Japanese encephalitis in Baoshan during this period (average angle=203.87, Z=205.08, P0.0001). The incidence peaks was on 238th day, the epidemic was during 200th day-274th day. Conclusion The seasonality of Japanese encephalitis was obvious in Baoshan from 2005 to 2014. The concentration degree and circular distribution indexes reflected the time distribution for Japanese Encephalitis in Baoshan accurately.