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 characterize the epidemiology of hand, foot and mouth disease (HFMD) cases caused by coxsackievirus group A type 6 (CV-A6) in Xi’an from 2016 to 2020 and provide evidence for the prevention and control of HFMD.Methods:The enterovirus (EV) types were identified using real-time RT-PCR. The data of HFMD cases were collected from the National Notifiable Infectious Diseases Reporting System of China Center for Disease Control and Prevention. Descriptive epidemiological method were used to analyze the distributions and the data were statistically analyzed with Excel 2007 and SPSS 18.0.Results:In the 4 034 HFMD cases, 17.85% had enterovirus group A type 71 (EV-A71) infections, 23.92% had coxsackievirus group A type 16 (CV-A16) infections, and 47.79% had other EV infections. 2 571 HFMD cases were randomly selected, including 1 268 other EV positive cases. The detection rate of CV-A6 in HFMD cases was 34.73% (893/2 571), and the constituent ratio of CV-A6 in other EV positive cases was 70.43% (893/1 268). The cases mainly occurred in children aged≤5 years (95.18%), more boys were affected than girls (1.47∶1). HFMD caused by CV-A6 was concentrated in April to June. Compared with EV-A71 and CV-A16, the clinical classification had significant difference in CV-A6 group ( χ2=139.55, P<0.001), but the ratio of sex and age-group had no significant difference ( F=2.74, P=0.065; χ2=2.43, P=0.297). Conclusions:The predominant pathogen of HFMD in Xi’an from 2016 to 2020 were other EV, among which CV-A6 accounted for the highest proportion in other EV positive cases. It is necessary to strengthen the prevention and control of HFMD caused by CV-A6 and carry out the surveillance for various pathogens of HFMD.

Objective:To explore the positive rates of 2019-nCoV nucleic acid at different time of courses of COVID-19.Methods:Patients with confirmed COVID-19 were enrolled in this study. Nasal and throat swabs were collected from different courses of disease. Real-time RT-PCR was used to detect 2019-nCoV nucleic acid.Results:From January 23 to February 20, 2020, a total of 120 confirmed cases of COVID-19 were reported in Xi’an, and 85 cases(70.83%) were positive in first detection. The COVID-19 cases included consistently nucleic acid positive and intermittently nucleic acid positive patients. 2019-nCoV nucleic acid could be detected in incubation period, and the longest observed duration of nucleic acid positive in this study was 26 days. The positive rate of 2019-nCoV nucleic acid was up to 84.21% on the 6th day, and the positive rate decreased as time passed during the course of COVID-19. Three patients (2.86%) were tested positive for 2019-nCoV nucleic acid again in nasal and throat swabs after discharge.Conclusions:The positive rate of 2019-nCoV nucleic acid was higher in the early stage of disease. 2019-nCoV nucleic acid can be detected in incubation period, and virus shedding may last for a long period.

Objective To investigate the effect of fluoxetine-exposure during pregnant period on depression-like behaviors and hippocampal BDNF in offspring mice.Methods Sixteen C57BL/6 pregnant mice were randomly divided into fluoxetine group (Flu group) and normal saline group (NS group),including 8 mice in each group.And the mice in the Flu group and NS group were treated with fluoxetine (10 mg/kg) and normal saline respectively by intragastric administration from the date of conception 9 to day 18.The adult offspring mice were divided into 8 groups including 4 subgroup with 8 in each group based on gender and circadian rhythm.That was Flu-MD group,Flu-MN group,Flu-FD group,Flu-FN group,NS-MD group,NS-MN group,NS-FD group and NS-FN group;"M" and "F" stands for gender;and "D"and "N" stands for circadian rhythm.The depression-like behavior of offspring adult mice was observed by tail suspension and forced swimming test,and the expression of brain derived neurotrophic factor (BDNF) in hippocampus was detected by Western blot.Results (1) There was no deformity in the adult offspring mice of NS group and Flu group;(2) In the tail suspension test and forced swimming test,there was no significant difference in cumulative immobility time between the Flu group and the NS group (P＞0.05).There was no significant difference in cumulative immobility time between male and female mice in NS group or Flu group (P＞0.05).There were significant differences in immobility time between Flu-MD group and Flu-MN group (tail suspension test:Flu-MD group (175.94± 30.93)s,Flu-MN group (127.65±44.91)s;forced swimming test:Flu-MD group (108.17±44.92)s,Flu-MN group (169.00±62.50) s,P＜0.05),and there were no significant difference in the rest groups.(3) There was no significant difference in the expression of BDNF protein between the Flu group and NS group (P＞0.05).Conclusion There is no phenotypic abnormalities on offspring when female mice were exposed to fluoxetine during their pregnancy period.It does not increase the occurrence of depression-like behavior of the adult offspring and does not affect the expression of BDNF in hippocampus.