Identification of the spatial-temporal cluster and risk factors of hepatitis E from 2017 to 2022 in Shanghai, China

Background Hepatitis E, caused by the Hepatitis E virus (HEV), is a global infectious liver disease primarily transmitted through fecal-oral and zoonotic routes. Despite the launch of a vaccine in China in 2011, hepatitis E remains a public health concern due to its diverse transmission routes and increasing sporadic cases. Herein, we aim to identify the potential case clusters and risk events at community-level in Shanghai to inform tailored strategy. Methods Data on HEV cases from 2017 to 2022 in Shanghai were collected from the National Notifiable Disease Reporting System (NNDRS) and supplemented with population and socio-economic data from Shanghai's communities. Descriptive and temporal analysis were applied to describe the epidemiological patterns, spatial-temporal scan analysis was used to identify potential case clusters, and binary logistic regression tests were conducted to explore the associations between risk factors and potential clusters. Results A total of 4,668 HEV cases were analyzed, with an average annual notification rate of 3.14 per 100,000 population in Shanghai from 2017 to 2022. Temporal analysis identified a significant temporal cluster from January 1st of 2017 to May 31th of 2019(RR  =  1.73, LLR =  135.74, P  < 0.001), and a seasonal cluster from December to May. Spatial-temporal analysis revealed the most likely cluster in urban areas, with additional clusters in suburban towns. Binary logistic regression indicated positive associations between the risk rank of the clusters and population density (OR _PD =7.367, P _PD <0.001), as well as the count of malls (OR _COM =1.531, P _COM =0.050), and a negative association with the distance to river (OR _DTR =0.742, P _DTR =0.048). Conclusions The spatial-temporal pattern of HEV in Shanghai during 2017 to 2022 suggested that although the communities with higher notification rate distribute in the southeast of Shanghai, the most likely cluster through spatial-temporal analysis per year locates in urban area, which is corresponding with the one scanned over 6 years. Investigation about HEV infectious cases related to potential transmission routes could be further operated to testify the causal effects and inform a more focused strategy to prevent the transmission of HEV.