Spatio-temporal evolution of Beijing 2003 SARS epidemic

ZhiDong Cao; DaJun Zeng; XiaoLong Zheng; QuanYi Wang; FeiYue Wang; JinFeng Wang; XiaoLi Wang

doi:10.1007/s11430-010-0043-x

Spatio-temporal evolution of Beijing 2003 SARS epidemic

Sci China Earth Sci. 2010;53(7):1017-1028. doi: 10.1007/s11430-010-0043-x. Epub 2010 May 12.

Authors

ZhiDong Cao¹, DaJun Zeng¹, XiaoLong Zheng¹, QuanYi Wang², FeiYue Wang¹, JinFeng Wang³, XiaoLi Wang²

Affiliations

¹ 1Key Laboratory of Complex Systems and Intelligence Science, Institute of Automation, Chinese Academy of Sciences, Beijing, 100190 China.
² 2Beijing Center for Disease Control and Prevention, Beijing, 100013 China.
³ 3State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101 China.

Abstract

Studying spatio-temporal evolution of epidemics can uncover important aspects of interaction among people, infectious diseases, and the environment, providing useful insights and modeling support to facilitate public health response and possibly prevention measures. This paper presents an empirical spatio-temporal analysis of epidemiological data concerning 2321 SARS-infected patients in Beijing in 2003. We mapped the SARS morbidity data with the spatial data resolution at the level of street and township. Two smoothing methods, Bayesian adjustment and spatial smoothing, were applied to identify the spatial risks and spatial transmission trends. Furthermore, we explored various spatial patterns and spatio-temporal evolution of Beijing 2003 SARS epidemic using spatial statistics such as Moran's I and LISA. Part of this study is targeted at evaluating the effectiveness of public health control measures implemented during the SARS epidemic. The main findings are as follows. (1) The diffusion speed of SARS in the northwest-southeast direction is weaker than that in northeast-southwest direction. (2) SARS's spread risk is positively spatially associated and the strength of this spatial association has experienced changes from weak to strong and then back to weak during the lifetime of the Beijing SARS epidemic. (3) Two spatial clusters of disease cases are identified: one in the city center and the other in the eastern suburban area. These two clusters followed different evolutionary paths but interacted with each other as well. (4) Although the government missed the opportunity to contain the early outbreak of SARS in March 2003, the response strategies implemented after the mid of April were effective. These response measures not only controlled the growth of the disease cases, but also mitigated the spatial diffusion.

Keywords: Beijing; control measures; morbidity rate; severe acute respiratory syndrome (SARS); spatial analysis; spatio-temporal evolution.