ABSTRACT
Objective@#To analyze the epidemiological characteristics and influencing factors of norovirus aggregation in primary and secondary schools in Haidian District of Beijing from 2015 to 2018,and to provide scientific basis for the prevention and control of school aggregation epidemic situation.@*Methods@#An epidemiological method was used to analyze the epidemic characteristics of norovirus aggregation in the primary and secondary schools in Haidian District of Beijing from January 2015 to December 2018. Multivariate Logistic was used to analyze the influencing factors of norovirus aggregation.@*Results@#A total of 74 cases of norovirus aggregation in primary and secondary schools in Haidian District of Beijing from 2015 to 2018 were reported, involving 52 primary and secondary schools. Totally 1 291 suspected cases and a median of 12.5 cases of single epidemic were reported. Winter and spring were high incidence season. There was significant difference in the incidence rate of epidemic situation in primary and secondary schools(χ2=98.82, P<0.01). There was significant difference in the incidence rate between men and women(χ2=55.56, P<0.01). A total of 648 samples and 486 positive samples were collected, with a positive rate of 75.00%, mainly GⅡ virus, accounting for 87.45%. Multivariate Logistic regression showed that the scale of school(>2 000，1 000~2 000), student’s hand hygiene habit,requirement for medical care after the outbreak is the influence factor of the outbreak(OR=3.78，2.95，8.25，2.88).@*Conclusion@#Poor hand hygiene habits are the most important risk factors for the outbreak, so schools and parents should cultivate children to develop good hygiene habits of washing hands before and after meals, and timely isolation of cases found in schools is also an important measure to prevent and control the epidemic.
ABSTRACT
Presummer, summer, and autumn bolls (PSB, SB and AB, respectively) in cotton are related to both maturity and yield. Therefore, studying their genetic basis is important for breeding purposes. In this study, we developed an association analysis panel consisting of 169 upland cotton accessions. The panel was phenotyped for PSB, SB and AB across four environments and genotyped using a Cotton SNP80K array. Single-nucleotide polymorphisms (SNPs) associated with these three traits were identified by a genomewide association study. A total of 53,848 high-quality SNPs were screened, and 91 significant trait-associated SNPs were detected. Of the 91 SNPs 33 were associated with PSB, 21 with SB and 37 with AB. Three SNPs for PSB (TM10410, TM13158 and TM21762) and five for AB (TM13730, TM13733, TM13834, TM29666 and TM43214) were repeatedly detected in two environments or by two methods. These eight SNPs exhibited high phenotypic variation of more than 10%, thus allowing their use formarker-assisted selection. The candidate genes for target traits were also identified. These findings provide a theoretical basis for the improvement of early maturity and yield in cotton breeding programmes.