Epidemiological Characteristics of Japanese Encephalitis in Guizhou Province,China,1971-2009

Objective The aim of the study was to establish the contemporary epidemiological characteristics of Japanese encephalitis (JE) in Guizhou Province.Methods A retrospective study of National Notifiable Disease Reporting System (NNDRS) data from 1971 through 2009,was conducted to ascertain the geographical,seasonal,and age distributions of JE incidence in Guizhou Province,China.Results A total of 68 425 JE cases were reported in Guizhou from 1971-2009.The JE cases occurred sporadically in all 9 prefectures of Guizhou,mostly among residents of rural areas.Seasonal distribution of JE remained consistent over the period from 1971-2009 with the main transmission season starting from June to September and peaking in August.JE occurred mainly in children under the age of 15 years with peak incidence in the 0-6-year age group.Pearson’s correlation analysis showed that JE vaccine distribution had a negative correlation with JE incidence rates during 1971-2009 (coefficient of correlation=-0.475,P<0.01).Conclusion Over the period of 1971-2009,the JE incidence rate had declined dramatically in terms of geographical and age distributions due to JE vaccination to children at risk.