Epidemic area and geographic distribution of Japanese encephalitis in Gansu province

Objective To analyze changing trend of Japanese encephalitis(JE) epidemic in Gansu province and Hexi Corridor and to examine the characteristics of JE epidemic in Hexi Corridor. Methods The data of field study and surveillance on JE in Gansu from 1958 to 2010 from National Notifiable Disease Reporting System were abstracted to analyze the changes in incidence and regional distribution of JE in Hexi Corridor before and after immunization of JE vaccine using descriptive epidemiology methods. Results From 1958 to 1980,the average annual incidence of JE was 0.65/100 000 in Gansu. There was no epidemic of JE in Gansu after JE vaccination in 1980 and the incidence of JE in 2010 dropped to 0.14/100 000.The areas at higher risk of JE epidemic were located in Tianshui,Pingliang,and Longnan city,which were the key areas of JE control and prevention in Gansu. From 1958 to 1980,there were totally 88 JE cases and the average annual incidence of JE was 0.13/100 000 in Hexi Corridor.From 1981 up to now,only one nonlocal incidence case of JE was reported. In August 2011,a total of 587 cases of suspected encephalitis were found through a survey among inpatient cases of country or above country level hospitals in seven countries in Hexi Corridor. Conclusion JE incidence in Gansu was significantly decreased in JE immunization era. The southeast of Gansu was key area of prevention and control and further investigation was necessitated to assess whether JE epidemic being undercontrol in Hexi Corridor.