Objective: To investigate the incidence trend and epidemic characteristics of notifiable infectious diseases in Nanjing City from 2004 to 2022, so as to provide the basis for improving the prevention, control, and monitoring strategies of infectious diseases. Methods: Data pertaining to notifiable infectious diseases reported in Nanjing City from 2004 to 2022 were retrieved from the Infectious Disease Surveillance System of Chinese Disease Prevention and Control Information System. Infectious diseases were classified by law and transmission routes. Temporal distribution incidence of notifiable infectious diseases were descriptively analyzed. The trends in incidence of notifiable disease were analyzed using annual percent change (APC) and average annual percent change (AAPC). Results: A total of 33 types of notifiable infectious diseases with 505 275 cases were reported in Nanjing City from 2004 to 2022. The average annual reported incidence was 347.45/105, showing a decreasing trend from 2018 to 2022 (APC=-13.499%, P<0.05), and there was no significant trend overall (AAPC=-1.586%, P>0.05). A total of 203 235 cases of 25 types of class A and B notifiable infectious diseases were reported, with an average annual reported incidence of 139.75/100 000, showing an overall decreasing trend (AAPC=-4.954%, P<0.05). Eight types of class C notifiable infectious diseases with 302 042 cases were reported, with an average annual reported incidence of 207.69/100 000. The reported incidence showed an increasing trend from 2004 to 2018 (APC=10.117%, P<0.05), and a decreasing trend from 2018 to 2022 (APC=-27.467%, P<0.05). There was no trend overall (AAPC=-0.360%, P>0.05). The reported incidence of blood-borne and sexually transmitted infectious diseases was the highest in class A and B infectious diseases, with an average annual reported incidence of 69.88/100 000, which was at a high epidemic level throughout the year, except February. The reported incidence of respiratory infectious diseases was 51.30/100 000, with a high reported incidence in April and December. The reported incidence of intestinal infectious diseases was the highest (178.06/100 000) in class C infectious diseases, with a high reported incidence in June and November. Conclusions The reported incidence of notifiable infectious diseases in Nanjing City was generally stable from 2004 to 2022. The peak incidence of respiratory infectious diseases occurred in winter and spring, and that of intestinal infectious diseases was in summer and autumn. It is necessary to strengthen the surveillance and intervention of blood-borne and sexually transmitted infectious diseases, respiratory infectious diseases, and intestinal infectious diseases to reduce the risk of infectious diseases.

Objective:To understand the reported incidence level, change of the trend, epidemic characteristics and spatial clustering of scrub typhus in Nanjing, to explore key seasons, populations and areas for prevention and control, and to guide formulation of scientific and precise prevention and control strategies and measures.Methods:The reported data of scrub typhus in Nanjing from January 1, 2011 to December 31, 2020 were collected in the "Infectious Disease Surveillance System" from Chinese Center for Disease Control and Prevention. The reported incidence level and change of the trend were analyzed, and the seasonal, population and spatial distribution characteristics were described. Global spatial autocorrelation analysis was carried out by ArcGIS 10.3 software, and the spatial clustering scanning was carried out by using FleXScan 3.1.2 software.Results:A total of 192 cases of scrub typhus were reported in Nanjing from 2011 to 2020. Median annual reported incidence was 0.21/100 000 (0.12/100 000 - 0.49/100 000). Totally 87.5% (168/192) of cases were reported from October to November, and the peak occurred in November (57.8%, 111/192). Among these cases, males accounted for 64.1% (123/192); and the median age was 59 years old (6 - 84 years old). The groups ≥60 years old and 45 - 59 years old accounted for 47.9% (92/192) and 31.2% (60/192), respectively, which accounted for 79.2% (152/192) in all groups. Farmers accounted for 43.8% (84/192), household chores and unemployed people accounted for 16.7% (32/192), retired persons accounted for 15.6% (30/192) and workers accounted for 6.8% (13/192), which accounted for 82.8% (159/192) in all occupations. The top four areas in the total number of reported cases were Jiangning District (23.4%, 45/192), Luhe District (22.9%, 44/192), Gulou District (10.4%, 20/192) and Jiangbei New Area (8.9%, 17/192), which accounted for 65.6% (126/192) in all districts. According to global spatial autocorrelation analysis, Moran's I = 0.34 ( Z = 5.90, P < 0.001). FlexScan 3.1.2 software scanned and detected two spatial clusters areas, the first-class of cluster area covered three streets in Jiangning District, one street in Yuhuatai District and two streets in Pukou District [restricted log likelihood ratio ( RLLR) = 26.91, P < 0.001]. The second-class of cluster area included six townships/streets in Luhe District and four streets in Jiangbei New Area ( RLLR = 26.48, P < 0.001). All the cluster areas were agriculture-related. Conclusions:The reported incidence level of scrub typhus in Nanjing is low and stable which belongs to a typical autumn epidemic area. The middle-aged and elderly population is the key population and the agriculture-related area is key area. It is suggested that scrub typhus should be included in the management of statutory or regional key infectious diseases in Nanjing. Additionally, training on diagnosis and treatment technology and information report management of scrub typhus need to be carried out, and comprehensive prevention and control interventions such as health education, personal protection, rodent prevention and control and vector control should be strengthened and implemented in the high incidence season.