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.

Objective:To understand the relationship between the RNA shedding time of SARS-CoV-2 infected persons and the single nucleotide mutation of the virus, the population of infected persons, underlying diseases and other factors, so as to provide more clues for the study of SARS-CoV-2 infection dynamics.Methods:The data of epidemiology, clinical manifestations, and underlying diseases of infected persons in a cluster epidemic of COVID-19 in Jiangsu province from July to September 2021 were collected. Nasopharyngeal swab samples of cases were collected, and the whole genome of the virus was sequenced by second-generation sequencing technology. The online analysis platform was used to judge the virus type and analyze the mutation site, and Cox proportional risk model was used to analyze the relationship between the RNA shedding time of SARS-CoV-2 and various research factors.Results:There were 350 persons who finally obtained the whole genome sequence of the virus in this COVID-19 outbreak, of which 60.3% were female, the median age was 49 years old (interquartile range, IQR: 37-65 years old)), and the median time of virus shedding was 33 days ( IQR, 26-44 days). The whole-genome sequencing analysis showed that compared with the Wuhan reference strain sequence, the infected persons’ sequence had 34~41 nucleotide mutation sites, belonging to VOC/Delta variant (B.1.617.2 evolutionary branch), and C346T, C1060T, T2803C, T7513C, A29681C were the main single nucleotide polymorphisms (SNPs) of this epidemic. Cox regression analysis showed that age, underlying disease, clinical classification, vaccination, SNP T2803C and T7513C had an impact on the RNA shedding time of SARS-CoV-2. The adjusted multivariate Cox regression result showed that age [ HR=0.73, 95% CI (0.55, 0.95)] and T7513C [ HR=0.37, 95% CI (0.18, 0.77)] were still the risk factors for the extension of SARS-CoV-2 RNA shedding time. Conclusions:This study analyzed the effects of the individual factors and viral single nucleotide variations on the time of viral RNA shedding. Those who were older, suffered from hypertension, had more severe clinical symptoms, were not vaccinated or incompletely vaccinated, and had T7513C mutation in the infected virus, had a risk of a long RNA shedding time of SARS-CoV-2, which should be given special attention and follow-up after rehabilitation.

Objective:To analyze the epidemiological and clinical characteristics of respiratory syncytial virus (RSV) infection in children in Jiangsu Province from 2014 to 2023.Methods:The acute respiratory infection cases in children aged 0-14 years were selected from outpatient/emergency or inpatient departments in 2 surveillance sentinel hospitals, respectively, in Nanjing, Suzhou and Taizhou of Jiangsu from 1 July 2014 to 31 December 2023, and RSV nucleic acid test was conducted and the intensity of the RSV infection was accessed by WHO influenza epidemiological threshold method, and case information and clinical data were collected. χ2 test was used to compare the differences between groups, and the Bonferroni method was used for pairwise comparisons between groups. Results:In 4 946 cases of acute respiratory infections, the RSV positive rate was 8.21% (406/4 946), and the age M( Q1, Q3) of the cases was 1 (0, 3) years. The RSV positive rate was 10.92% (258/2 362) during 2014-2019 and 6.06% (118/1 948) during 2019-2023, the difference was significant ( χ2=31.74, P<0.001). RSV infection mainly occurred from October to March during 2014-2019, with the incidence peak in December and moderate or higher intensity. The seasonality of RSV infection was not obvious during 2019-2023, with low intensity. The RSV positive rate was highest in children in age group 0- years (17.85%, 151/846), and the positive rate declined gradually with age ( χ2=184.51, P<0.001). The RSV positive rate was higher in inpatient cases (9.84%, 244/2 480) than in outpatient/emergency cases (6.57%, 162/2 466) ( χ2=17.54, P<0.001). In the 155 RSV infection cases with complete clinical data, the clinical symptoms mainly included cough (99.35%, 154/155), fever (55.48%, 86/155), and shortness of breath (45.16%, 70/155). In the cases aged <6 months, the proportion of those with fever was low, but the proportion of those with shortness of breath, transferred to intensive care units, and receiving oxygen therapy were higher (all P<0.05). Children aged <6 months and those with underlying diseases were more likely to have severe RSV infection (all P<0.05). Conclusions:RSV infection in children in Jiangsu Province showed seasonal prevalence in winter from 2014 to 2019. Since 2020, the seasonal characteristics of the epidemic have changed, the epidemic period has been dispersed and the epidemic intensity has decreased. Infants <1 year old were at high risk for RSV infection, and those <6 months old and with underlying diseases might have severe infection.