Epidemiology of bacillary dysentery in Ningbo, Zhejiang,2004-2011

Objective To understand the epidemiological characteristics of bacillary dysentery in Ningbo and provide scientific evidence for the control and prevention of bacillary dysentery. Methods Descriptive epidemiological analysis was conducted on the incidence data and etiological surveillance Results of bacillary dysentery in Ningbo from 2004 to 2011. Results The incidence of bacillary dysentery ranged from 8.35/lakh to 42.59/lakh during this period, the annual average incidence was 24.25/lakh. No outbreak of bacillary dysentery had been reported since 2007. The cases occurred all the year round and peaked during August-September. All age groups were affected by bacillary dysentery, but the incidence in age group 0-4 years was highest, followed by that in age group 85 year. The incidence was higher in males than in females in age groups 0-19 years and 75 years. Compared with neighboring counties, the incidence in urban area was higher. The cases were mainly distributed in children outside child care settings, farmers, workers and students. The etiological surveillance indicated that the major pathogens were Shigella flexneri and Shigella sonnei with the positive rates of 59.76% and 39.02%, respectively. Conclusion The incidence of bacillary dysentery declined year by year and remained at low level in Ningbo.