ABSTRACT
Objective: To analyze the epidemiological characteristic and tracing process of an outbreak of COVID-19 in a sea-land border city (D city) of Guangxi in December 2021, and provide scientific data for for the emergency management and scientific traceability of similar outbreaks in the future. Methods Epidemiological investigation of cases was carried out under the guideline of the Novel Coronavirus Epidemiological Investigation Programme on Cases of Pneumonia (Edition 8). RT-PCR method was used for samples testing. Furthermore, positive samples were analyzed by whole-genome sequence and phylogenetic analysis. R software 4.1.3 version was used for data analysis. Results There were 20 cases in this outbreak which related 6 families. The average incubation period was (4.6..2.2) d. Compared with the Wuhan reference strain (NC_045512), the genome sequence analysis showed that there were 35-36 nucleotide mutation sites in the novel Coronavirus genome sequence of 19 local cases, which belonged to VOC/Delta variant strain (AY.57 evolutionary branch). The 11 amino acid mutation sites were the same in all the novel Coronavirus spikes (S) proteins, which were highly homologous to the 2 COVID-19 genome sequences uploaded from a neighboring country in the GISAID genome database. Conclusion This outbreak was caused by fishermen who were infected by contacting with persons of neighboring country in the public sea area and causing located community transmission. The management of border villagers and the monitoring of epidemic strains should be strengthened to detect and deal with the outbreak as early as possible in the future.
ABSTRACT
To analyze the epidemiological characteristics and related factors of norovirus in Guangxi from 2015 to 2020, and to provide scientific recommendations for norovirus prevention and control. Methods The foodborne diseases surveillance data were collected from 11 sentinel hospitals through the National Foodborne Disease Monitoring and Reporting System from 2015 to 2020. R software with version 4.0.3 was used for descriptive and statistical analysis, including epidemic curve, chi-square test, and trend chi-square and so on. Logistic regression was used to analyze norovirus-related factors, OR values and 95% confidence intervals were calculated respectively with the statistical test level of P < 0.05. Results There were 1 008 norovirus cases detected, with a detection rate of 12.75% (1 008/7 903). Children with age less than 5 years (OR=1.43, 95%CI: 1.13-1.82) and patients at age 20-45 (OR=1.45, 95%CI: 1.13-1.87) were high risk population. The detection rate was higher in autumn (OR=1.29, 95%CI: 1.08-1.53) but lower in summer (OR=0.67, 95%CI: 0.55-0.80). In addition, the tourist area (Guilin City) presented a higher detection rate than other areas (OR=1.41, 95%CI: 1.10-1.80). Aquatic products (OR=1.40, 95%CI: 1.03-1.91), meat and dairy products (OR=1.31, 95%CI: 1.06-1.61) were high-risk foods for norovirus infection. The prevention and control policies of COVID-19 can reduce the possibility of norovirus by 61% (OR=0.39, 95%CI: 0.31-0.49) showed a declining trend (Trend X2=85.33, P < 0.001). In addition, prolonged visit time can lead to 19%-23% decrease in the detection rate of norovirus (OR24-48 hours=0.81, 95%CI: 0.70-0.95;OR>48 hours=0.77, 95%CI: 0.63-0.93). Conclusions The epidemic of norovirus presented seasonal and regional distribution in Guangxi with a declining detection rate trend in diarrhea patients during recent 6 years. Young children were high-risk population in infection norovirus. The intake of seafood can increase the risk of norovirus infection. The prevention and control policies of COVID-19 can sharply decrease the possibility of infection norovirus. The monitoring of key foods such as seafood should be strengthened, and the early screening of suspected cases should be taken. The norovirus monitoring should be improved to ensure the health of the population.