Objective  To analyze variations in incidence and prevalence characteristics of Japanese encephalitis (JE) in Gansu province between 2004 and 2017 for providing evidences to the prevention and control of JE.

  Methods  We collected data on JE in Gansu province from National Notifiable Disease Information Reporting System and analyzed the data with descriptive epidemiology methods.

  Results  Totally 1 018 JE cases were reported during the period in the province. With vaccinations of JE vaccine, the peak incidence interval of JE changed from 3 – 4 years to 9 – 10 years; the JE epidemic area extended from the southeastern to the central region of the province; the population with high incidence shifted from the children under 14 years old to the adults, with a decreased proportion of the reported cases less than 14 years old from 69.56% in 2004 to 4.70% in 2017 (χ²_trend = 215.766, P < 0.001). The proportion of the JE cases aged 15 – 39 years old showed no significant variation (χ²_trend = 1.29, P = 0.256), with an average ratio of 23.97%. The proportion of JE cases aged 40 years and above increased from 6.52% in 2004 to 70.72% in 2017 (χ²_trend = 148.466, P < 0.001). The majority of the JE cases shifted from farmers, students, small and scattered living children to farmers (χ²_trend = 178.646, P < 0.001).

  Conclusion  The area with high incidence of JE extended and JE epidemic was well controlled among children but not in the adults in Gansu province between 2004 and 2017.