Socio-climatic factors and Japanese Encephalitis transmission in Shaanxi, China

Abstract

Background: Evidences indicated that climate and socio-demographical factors were associated with incidence of Japanese Encephalitis (JE). However, most of them did not consider seasonality when using spatial analytical approaches. This study explored the association of climate and socio-demographical factors with JE incidence in Shaanxi, China using spatial analysis. Methods: Aggregated JE data (2007-2014) from 107 counties in Shaanxi were supplied by Shaanxi Provincial Center for Disease Control and Prevention. Climate and socio-demographical and climate data were provided by China Meteorological Administration and China Bureau of Statistics, respectively. A Bayesian conditional autoregressive model was used to examine the association of climate and socio-demographical factors with JE across different counties within Shaanxi after adjusting for seasonality. Results: A total of 674 JE cases were included in this study. 671 cases occurred between June and October and 658 occurred between July and September across the whole study period. The north of Shaanxi had lowest JE incidence while the south had highest JE incidence in general. In the first model (data from June to October), humidity was positively associated with JE incidence across counties (RR=1.062, 95%CI: 1.026-1.097). Counties with higher percentage of urban population (PUP) had lower JE incidence (RR=0.990, 95%CI: 0.980-0.999). In the second model (data from July to September), counties with higher humidity were accompanied with lower JE incidence (RR=1.054, 95%CI: 1.013-1.096). Other variables (e.g., rainfall, temperature and population density) were not significantly associated with JE incidence in this study. Conclusion: Humidity and urbanization were more significantly associated with JE incidence across counties than other variables. JE control and prevention program should be strengthened in rural areas, particularly during summer and early autumn.