Spatial and Temporal Patterns of Primary Syphilis and Secondary Syphilis in Shenzhen, China

Objective To learn the spatial and temporal patterns of primary syphilis and secondary syphilis in Shenzhen and to provide evidence for carrying out further research on syphilis.Methods Primary syphilis and secondary syphilis cases among residents in Shenzhen between 2005and 2009(n=11 303) were geocoded at street office level (n=55) based on residence at the time of diagnosis. Both spatial and space-time scan statistics were used to identify clusters of street office by using SaTScan software. Results In the purely spatial analyses, clusters were seen in the junction of the Baoan district and Nanshan district (Xinan, Xixiang, Nanshan and Nantou street office) and in the region near Hong Kong (Dongmen, Shekou, and Futian street office), as well as in the other streets where entertainment industry was relatively developed (Longhua, Huafu, Huangbei and Cuizu street office). The clusters had not changed much in the first four years, but nine clusters appeared in 2009.Annually, the most likely clusters were located in Longhua (2005, P≤0.001, RR=3.34), Bamboo (2006, P≤0.001, RR=9.59), Huafu (2007, 2008 years, P≤0.001, RR values were 4.18 and 4.75)and Cuizu (2009, P≤0.001, RR=8.02). In the space-time scan analysis, we found 16 significant clusters, which were similar to the pure spatial analyses. However, regional difference were also found, with the most likely cluster was the Guiyuan street office in 2006. Conclusion Spatial and space-time scan statistics seemed to be effective ways in describing the circular disease clusters. We have had a better understanding on spatial and temporal patterns of primary syphilis and secondary syphilis in Shenzhen through spatial and space-time scan statistics of syphilis surveillance data in the recent years. The changes of spatial and temporal patterns of primary syphilis and secondary syphilis were also described by SaTScan software, which also provided useful reference for the preventive strategies on sexually transmitted diseases as well as on HIV. Useful information was also provided for financial investment and cost-effective studies. Key words: Syphilis; Space-time scan statistic; Epidemiology