ABSTRACT
Objective@#To investigate the epidemiological characteristics of 45 norovirus clusters in Baoshan District, Shanghai Municipality from 2019 to 2021, so as to provide the evidence for improving the management of norovirus clusters. @*Methods@#The epidemiological characteristics and laboratory testing of 45 norovirus clusters were collected in Baoshan District from 2019 to 2021, and the temporal distribution, population distribution, distribution of places of norovirus clusters, clinical manifestations, laboratory testing results, origin of norovirus infection and transmission routes of norovirus clusters were analyzed using a descriptive epidemiological method. @*Results@#A total of 45 norovirus clusters involving 29 379 individuals were reported in Baoshan District from 2019 to 2021, and 435 cases with norovirus infections were identified, with an average attack rate of 1.48%. Norovirus infection most often occurred from November to April of the following year, and the infection predominantly occurred among students (408 cases, 93.79%). There were 25 norovirus clusters in kindergartens (55.56%), 18 clusters in primary and middle schools (40.00%), one cluster in a social care facility and one cluster in a geriatric ward. Vomiting was the predominant clinical symptom (416 cases, 95.63%). The positive rate of norovirus was 37.35% in 597 samples. There were 40 norovirus clusters caused by the norovirus GⅡ genotype (88.89%), and the median duration of the norovirus cluster was 6 days (interquartile range, 1 day). In addition, 82.22% of the norovirus clusters reported to centers for disease control and prevention within 1 day,and 88.89% of the clusters were transmitted through human to human transmission or vomitus of cases.@*Conclusion@#The norovirus clusters predominantly occur in winter/spring and among students in Baoshan District from 2019 to 2021. Kindergartens and primary and middle schools are main places of norovirus infections, and the norovirus GⅡ genotype is the main type of pathogens. Human-to-human transmission and exposure to patients' vomitus are the main routes of transmission.
ABSTRACT
Objective@#To describe the clinical features, causal agent and transmission mode of a fever outbreak in a school in Shanghai.@*Methods@#Field epidemiological approaches including case definition development, searching for contacts, distribution of diseases description, environmental sampling and laboratory testing.@*Results@#A total of 16 influenza like cases were included, all concentrated in the one class of grade two, including 15 students and 1 teacher. Among student cases, the incidence rate was 36.59% (15/41), the average age was 7.4 years, the incidence rate was 36.84%(7/19) for boys, 36.36%(8/22) for girls. The clinical course was 5-15 days, with the median of 9 days, and 18.75%(3/16) of the cases stayed studying while sick. The nasopharyngeal swab specimens in 16 cases all tested positive for influenza B, of which 11 tested positive for mycoplasma pneumoniae and 1 case also tested positive for coronavirus OC43. Body temperature, number of mononuclear cells, and treatment time of patients infected with Influenza B and mycoplasma pneumoniae were higher than those of patients infected with influenza B alone( P <0.05). The outbreak lasted for 12 days, all sick students were treated and discharged from hospital, with no severe cases or death, and the outbreak was effectively controlled.@*Conclusion@#This campus cluster outbreak caused by influenza B and mycoplasma pneumoniae. Patients with influenza B with mycoplasma pneumoniae have severe symptoms and a long course of illness, suggesting the importance of early management of the epidemic.