Objective: To investigate risk factors and epidemiological characteristics of bacillary dysentery outbreaks in three schools, and to provide scientific basis for the prevention and control of the epidemic in the future. Methods: Case definition was established. All suspected, possible and confirmed cases of all students and faculty members from 3 schools (A, B, C) were selected for epidemiological investigation. Control group was used for case-control analysis, and relevant samples were collected for laboratory testing. Results: A total of 132 cases were found in 3 schools, all of which were from students, with the incidence rate of 17.74%. The morbidity in kindergarten A was 20.00%, in center primary school B it was 21.74%, and in junior middle school C it was 11.61%. Cohort studies and casecontrol studies suggested that schools are exposed places and that washing hands with raw water in schools was possible risk factor [OR(95%CI) =4.50(1.01-20.11)]. Nine stool samples were tested in laboratory, among which 8 were positive for Shigella(88.99%), and Shigella was detected in the end nodes of school s pipeline network, the water samples from canteen bucket, and the floor drains of sewer pipe. Conclusion The bacillary dysentery outbreaks in 3 schools was caused by Shigella, which may be due to fecal contamination of domestic water in 3 schools before the start of the school year. It is suggested to strengthen the management of centralized water supply and construction in rural areas, intensify the supervision at all levels, and sanitation and disinfection before school opens at all levels.

Objective To learn the diagnosis and treatment of brucellosis patients in Suide County of Shaanxi Province in 2015,and to provide a scientific basis for making accurate prevention and control measures.Methods All the cases diagnosed as brucellosis in Suide County from January 1 to December 31 in 2015 and lived in this county were retrospectively investigated by case questionnaire survey,including basic information,medical procedures,and epidemiological contacts.Descriptive statistical analysis was performed using SPSS 18.0 software.Results In 2015,75 cases of brucellosis were diagnosed in Suide County,75 questionnaires were distributed,with 53 completed questionnaires returned.The average age of respondents was (49 ± 14) years old,of which 84.9％ (45/53) were male and 94.3％ (50/53) were farmers,except one case was actively monitored by Suide County Centre for Disease Control and Prevention then treated,the rest of the patients were treated after the onset of the disease.Of the 52 patients,one patient was diagnosed after one visit,accounting for 25.0％ (13/52);one patient was diagnosed after at least 4 visits,accounting for 3.8％ (2/52).The cumulative diagnosis rate at provincial-level hospitals was 1/3 and that at disease prevention and control institutions was 92.7％ (51/55),there were no confirmed cases in municipal hospitals,county hospitals,township hospitals,village clinics and individual clinics.For the first reason to see a doctor,65.4％ (34/52) of the patients were fever or accompanied by sweating,fatigue,arthralgia and waist and leg pain.The medians from onset to treatment between the first diagnosis,and 2,3,4 visits were 15,18,27,45 days,respectively;the median from onset to diagnosis was 21 days,ranging from 2 to 182 days.Totally 84.9％ (45/53) patients had a history of exposure to animals,of which 97.8％ (44/45) had contacted the sheep.Conclusions The cases in Suide County are mainly adult male farmers,and the diagnosis rate at hospitals below municipal level is low.It is recommended to strengthen the health intervention of high-risk groups and improve the level of diagnosis and treatment of primary medical staff.

Objective:To study the epidemic characteristics of kala-azar in Shaanxi Province, and to provide scientific basis for formulating effective prevention and control measures.Methods:Information of kala-azar confirmed cases and clinically diagnosed cases whose current addresses were reported in Shaanxi Province in the Surveillance Report Management System of China Disease Control and Prevention Information System from 2011 to 2022 was collected. Trend analysis was made on the number of cases in each year, and descriptive epidemiological methods were used to analyze the onset time, regional and population distribution characteristics and the time interval from onset to diagnosis of kala-azar cases.Results:A total of 225 kala-azar cases were reported in Shaanxi Province from 2011 to 2022, and the number of cases showed an increasing trend (χ 2trend = 98.50, P < 0.001), with the highest number in 2020 (42 cases). The onset time was mainly from March to May (77 cases, 34.22%). The top three cities with the number of reported cases were Hancheng (65 cases, 28.89%), Shangluo (47 cases, 20.89%) and Weinan cities (44 cases, 19.56%). The male to female ratio was 1.74∶1.00 (143/82), the age of onset was mainly concentrated in the age group of 36 - 60 years old (111 cases, 49.33%), and the occupation was mainly farmers (150 cases, 66.67%). The median interval from onset to diagnosis was 11 days, and 78.22% (176/225) of the cases were diagnosed within 1 month. Conclusions:From 2011 to 2022, the overall incidence of kala-azar in Shaanxi Province has showed an upward trend, with the main population being middle-aged male farmers. The main affected areas are Hancheng, Shangluo and Weinan cities. It is urgent to strengthen the surveillance and prevention and control of kala-azar in key populations and key regions.

Objective: To understand the dynamics and epidemiological characteristics of hand, foot and mouth disease (HFMD) in Shaanxi province during 2009-2018 and provide evidence for prevention and control of HFMD. Methods: Information on HFMD was collected from the Chinese Disease Prevention and Control Information System in Shaanxi Province during 2009-2018 and was analyzed by descriptive, dynamic geometric series averaging and circular distribution methods. Results: The annual average incidence rate of HFMD was 140.04/100 000 in Shaanxi province during 2009-2018. The highest incidence rates were seen in age groups as 1-year olds (3 494.24/100 000), 2-year olds (2 734.79/100 000) and 3-year olds (2 608.58/100 000). The highest reported mortality rates appeared in: 1-year olds as 1.42/100 000, 2-year olds as 0.77/100 000) and 0-year olds (0.53/100 000). The incidence rate increased most rapidly in the 1-year olds and the 0-year olds groups. The top three incidence rates were reported in Xi’an (251.34/100 000), Weinan (161.21/100 000) and Xianyang (123.73/100 000) cities in Guanzhong area of Shaanxi province. In the whole province, incidence rate was on the rise, and the average increases of incidence rates were all greater than zero in these cities. The proportion of severe cases in most cities somehow declined. Results from the circular distribution method estimated that the peak incidence would appear in April 10-11 each year, and the high incidence season was from April to July. In 2018, the composition of enterviruses (EV) 71 was 26.47% (1 303/4 922). In 2014 to 2018, the proportion of Coxsackie virus A16 (Cox A16) was between 20.06%(753/3 753) and 23.08% (855/3 705). The proportions of other EVs increased from 6.09% (14/230) to 51.91% (2 555/4 922) during 2009-2018. Conclusions The overall incidence rate of HFMD was increasing, with high risk population appeared in children under 3 year olds, in Shaanxi province during 2009-2018. However, both mortality and fatality rates were declining, with severe cases also showing a downward trend in most of the areas. Composition of pathogens was changing over time.

A total of 245 cases of COVID-19 in Shaanxi Province reported in the China information system for disease control and prevention as of February 24, 2020 were selected as the research objects, the cases are divided into imported cases (116 cases, 47.3%) and local cases (129 cases, 52.7%), their basic characteristics, time distribution, transmission mode, intergenerational interval and latent period transmission are analyzed. The age of local cases [(51.74±15.67) years old], female patients (69 cases, 53.5%), housework and retired staff (40 cases, 31.0%), and patients isolated at the time of onset (50 cases, 38.8%) were higher than imported cases, respectively[(40.66±15.41) years old, (45 cases, 38.8%), (21 cases, 18.1%), (17 cases, 14.6%)] ( P values were < 0.05); The infection rate was 0.8% (31/3 666) in close contacts with local cases, which was lower than imported cases 2.0% (69/3 435) ( P<0.001); The main source of infection in local cases was relatives (70 cases, 54.3%), and the main way of infection was living together and party (90 cases, 69.8%); the proportion of latent period transmission in our province was 15.5% (20 cases), and the interval between the second-generation case and the source of infection was about 4 days, and the interval between generations was about 6 days. In summary, the main way of infection of local cases in Shaanxi Province was living together and party, there were a certain proportion of latent period transmission cases at present, it's suggested that the investigation of close contacts should be started 4 days or earlier before the onset of the case.

A total of 245 cases of COVID-19 in Shaanxi Province reported in the China information system for disease control and prevention as of February 24, 2020 were selected as the research objects, the cases are divided into imported cases (116 cases, 47.3%) and local cases (129 cases, 52.7%), their basic characteristics, time distribution, transmission mode, intergenerational interval and latent period transmission are analyzed. The age of local cases [(51.74±15.67) years old], female patients (69 cases, 53.5%), housework and retired staff (40 cases, 31.0%), and patients isolated at the time of onset (50 cases, 38.8%) were higher than imported cases, respectively[(40.66±15.41) years old, (45 cases, 38.8%), (21 cases, 18.1%), (17 cases, 14.6%)] ( P values were < 0.05); The infection rate was 0.8% (31/3 666) in close contacts with local cases, which was lower than imported cases 2.0% (69/3 435) ( P<0.001); The main source of infection in local cases was relatives (70 cases, 54.3%), and the main way of infection was living together and party (90 cases, 69.8%); the proportion of latent period transmission in our province was 15.5% (20 cases), and the interval between the second-generation case and the source of infection was about 4 days, and the interval between generations was about 6 days. In summary, the main way of infection of local cases in Shaanxi Province was living together and party, there were a certain proportion of latent period transmission cases at present, it's suggested that the investigation of close contacts should be started 4 days or earlier before the onset of the case.

Objective:By analyzed the transmission patterns of 4 out of the 51 COVID-19 cluster cases in Shaanxi province to provide evidences for the COVID-19 control and prevention.Methods:The epidemiological data of RT-PCR test-confirmed COVID-19 cases were collected. Transmission chain was drawn and the transmission process was analyzed.Results:Cluster case 1 contained 13 cases and was caused by a family of 5 who traveled by car to Wuhan and returned to Shaanxi. Cluster case 2 had 5cases and caused by initial patient who participated family get-together right after back from Wuhan while under incubation period. Cluster case 3 contained 10 cases and could be defined as nosocomial infection. Cluster case 4 contained 4 cases and occurred in work place.Conclusion:Higher contact frequency and smaller places were more likely to cause a small-scale COVID-19 cluster outbreak, with potential longer incubation period. COVID-19 control strategies should turn the attention to infection prevention and control in crowded places, management of enterprise resumption and prevention of nosocomial infection.

Objective:To understand the incidence trend and epidemiological characteristics of COVID-19 in Shaanxi province.Methods:The incidence data of COVID-19 reported in Shaanxi as of 22 February, 2020 were collected for an epidemiological descriptive analysis.Results:A total of 245 confirmed cases of COVID-19 were reported in Shaanxi. Most cases were mild (87.76%). As time passed, the areas where confirmed cases were reported continued to increase. The case number in Xi’an was highest, accounting for nearly half of the total reported cases in the province. The epidemic pattern in Shaanxi had gradually shifted from imported case pattern to local case pattern, and the transmission of local cases was mainly based on family cluster transmission. The confirmed cases from different sources had caused the secondary transmission in Shaanxi. After February 7, the number of reported cases began to fluctuate and decrease stably, indicating a decrease-to-zero period.Conclusions:At present, the overall epidemic of COVID-19 in Shaanxi has gradually been mitigated. However, considering the approaching of return to work and study and the increasing of imported cases from other countries, the prevention and control of COVIS-19 in Shaanxi will face new challenges.

【Objective】 To assess the epidemiological characteristics and transmission risk of asymptomatic COVID-19 infection in Shaanxi Province. 【Methods】 A dense population database of COVID-19 cases in Shaanxi Province was constructed as of March 26, 2020, and 28 asymptomatic infected patients were selected through case epidemiological investigation report for descriptive analysis. 【Results】 In Shaanxi Province, the majority of asymptomatic COVID-19 infections were in the 20-59 years old group, and women took up a higher proportion than men. 82.14% of asymptomatic infections were found in the centralized isolation state. Nearly 80% of asymptomatic infections and confirmed cases were mainly exposed by living together in the family. The median number of days from last contact with the source of infection for all asymptomatic infected persons was 13, with 3 (10.71%) showing clinical symptoms. Epidemiological investigations showed that asymptomatic infections could spread as a result of shared family life. 【Conclusion】 At present, imported cases in Shaanxi Province continue to exist. Considering the concealed transmission of asymptomatic infections, prevention and control work is still facing challenges.