Objective: To analyze the epidemiological characteristics of dengue fever outbreaks in schools from Guangzhou in 2024, so as to provide a reference for formulating targeted prevention and control policies and measures. Methods: By using the National Infectious Disease Surveillance Information Reporting Management System to obtain information on dengue fever cases in Guangzhou from January 1st to December 31st, 2024. Descriptive data analysis was conducted on the temporal distribution, regional distribution, and school distribution of dengue fever outbreaks in schools. A mediation effect model was used to analyze the mediating effect of the time between onset and reporting between the type of school and the occurrence of recurrent cases. Results: In 2024,12.41% (385 cases) of dengue fever cases in Guangzhou involved schools, with 300 schools affected. Among these, 16 schools (5.33%) reported cluster outbreaks, and 24 schools (8.00%) reported secondary cases. The first dengue case at the school was reported at 26 July and the last case was reported at 4 December, the peak reporting period for cases was October 7 to November 3. The incidence of secondary cases in schools in central urban areas (5.19%) was lower than that in suburban schools ( 17.39 %), and the difference was statistically significant ( χ 2=9.15, P <0.01). The time from onset to reporting partially mediated the relationship between school type and the occurrence of recurrent cases ( β=0.23, P <0.05), accounting for 21.50% of the total effect. Conclusions Dengue fever is a key infectious disease facing schools in Guangzhou during summer and autumn. Surveillance of dengue fever outbreaks in schools should be strengthened during the peak season to reduce the risk of cluster outbreaks and the occurrence of secondary cases.

Objective:To identify a novel reassortant H3N2 avian influenza virus using nanopore sequencing technology and analyze its genetic characteristics.Methods:The positive samples of the H3N2 avian influenza virus, collected from the external environment in the farmers' market of Guangzhou, were cultured in chicken embryos. The whole genome was sequenced by targeted amplification and nanopore sequencing technology. The genetic characteristics were analyzed using bioinformatics software.Results:The phylogenetic trees showed that each gene fragment of the strain belonged to the Eurasian evolutionary branch, and the host source was of avian origin. The HA gene was closely related to the origin of the H3N6 virus. The NA gene was closely related to the H3N2 avian influenza virus from 2017 to 2020. The PB1 gene was closely related to the H5N6 avian influenza virus in Guangxi Zhuang Autonomous Region and Fujian Province from 2016 to 2022 and was not related to the PB1 gene of the H5N6 avian influenza epidemic strain in Guangzhou. The other internal gene fragments had complex sources with significant genetic diversity. Molecular characteristics indicated that the strain exhibited the molecular characteristics of a typical low pathogenic avian influenza virus and tended to bind to the receptors of avian origin. On important protein sites related to biological characteristics, this strain had mutations of PB2-L89V, PB1-L473V, NP-A184K, M1-N30D/T215A, and NS1-P42S/N205S.Conclusions:This study identified a novel reassortant H3N2 avian influenza virus by nanopore sequencing, with the PB1 gene derived from the H5N6 avian influenza virus. The virus had a low ability to spread across species, but further exploration was needed to determine whether its pathogenicity to the host was affected.