Objective: To investigate an outbreak of acute gastroenteritis at a vocational and technical school in Shaanxi Province in 2024, ao as to provide the reference for the handling of school outbreaks. Methods: The conducted case searches, individual case investigations, and on-site hygienic investigations were established in accordance with the Guidelines on outbreak investigation, prevention and control of Norovirus infection (2015). The potential risk factors were analyzed by case-control study. Anal swab samples from cases and all canteen staff, as well as environmental swab samples were collected to detect common intestinal pathogens. All reserved food samples in canteen were collected to test for common pathogenic bacteria. Results: From October 26 to November 5, 2024, a cumulative total of 53 cases were reported, with an attack rate of 1.47%. The main clinical symptoms included vomiting (83.02%), abdominal pain (56.60%), diarrhea (30.19%), and fever (26.42%). The epidemic curve suggested an intermittent common-source outbreak, with no obvious clustering characteristics in terms of the population and spatial distribution of cases. The case-control analysis revealed that having dinner at the rice-with-dishes-on-top stall on the first floor of the canteen on October 28 was a risk factor for illness (OR=11.025, 95%CI: 2.186-55.601). GⅡ norovirus was detected as positive in anal swab samples from 6 cases and 2 asymptomatic infected canteen staff, as well as in 3 environmental swab samples from the rice-with-dishes-on-top stall. The test results for common pathogenic bacteria in the reserved food samples were all negative. Conclusions This outbreak was caused by an acute gastroenteritis epidemic induced by GⅡ norovirus infection, with a transmission pattern consistent with an intermittent homologous outbreak. The possible source of infection was asymptomatic infected canteen staff mainly through foodborne trasmission, and having meals at the rice-with-dishes-on-top stall was the primary risk factor for this outbreak.

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 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.

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.