[Spatio-temporal clustering of hepatitis A in Gansu provice, 2004-2018]

Objective: To understand the characteristics of spatiotemporal clustering on hepatitis A in Gansu province and to provide evidence for hepatitis A prevention and control. Methods: Data related to hepatitis A were retrieved from National Notifiable Disease Report System, ArcGIS 10.3 and SaTScan 9.1 in Gansu province from 2004 to 2018. Results: The annual average report incidence rate of hepatitis A was 10.91/100 000, showing a descending trend with no periodic or seasonal features. After the implementation of national expanded immunization program, high annual incidence rates had been seen in Linxia Hui autonomous prefecture and Gannan Tibetan autonomous prefecture. From 2004 to 2012, the lowest RR value appeared in the 0-9 age group (P=0.000) while the highest RR value was in the over 60 age group during 2013-2018 except for the age 0-9 group in 2015. The annual average incidence rate was increasing from south to north and west to east, across the territory. Results from the temporal scanning program revealed that the incidence of hepatitis A was temporally aggregated from 2004 to 2018. For spatio-temporal scanning of 2004-2008, data showed one most likely cluster area (radius: 91.95 km, Time frame: 2004-2005), apparel mainly in Linxia and Longnan cities. Results from the spatio-temporal scanning program of 2009-2018 also showed that the most likely cluster areas (radius: 183.26 km, Time frame: 2009-2012) were in Gannan, Linxia, Dingxi and Longnan areas. Conclusions: The reported incidence rates of hepatitis A were declining, without significant periodic or seasonal pattern in Gansu province from 2004 to 2018. In the 0-9 years-old group, the incidence rate showed the lowest, while the highest was in the 60 year-olds group. Spatio-temporal clustering of hepatitis A was observed in Gansu province from 2004 to 2018. Strategies on prevention and control of the disease should be targeted in the southwest regions of the province.