Abstract: Objective　To investigate the epidemiological characteristics and control measures of dengue fever in Zhongshan City in 2024, so as to provide insights into optimization of dengue fever control strategies in the city. Methods　Data pertaining to dengue fever cases in Zhongshan City in 2024 were collected from the Infectious Disease Reporting System of China Disease Prevention and Control Information System, and the epidemiological characteristics of the cases were analyzed using a descriptive statistical method. The density of Aedes albopictus mosquito was monitored across all 23 townships (subdistricts) using Breteau index (BI) and mosquito ovitrap index (MOI) at midmonth each month from March to December 2024. In addition, the climatic characteristics, case reporting patterns, and corresponding control measures were analyzed during different phases of dengue fever epidemics in Zhongshan in 2024. Furthermore, real⁃time quantitative reverse transcription PCR (RT⁃qPCR) assay was employed to serotype the dengue virus among local dengue fever cases with unknown sources of infections. The dengue virus envelope (E) gene was sequenced using Sanger sequencing among dengue fever cases without apparent epidemiological links. A phylogenetic tree was constructed using the neighbor⁃joining method to infer major transmission chains during the dengue fever epidemics.  Results　A total of 952 dengue fever cases were reported in Zhongshan City in 2024, including 879 local cases, 57 domestically imported cases from other regions, and 16 overseas imported cases, representing the largest outbreak in nearly two decades. The first local dengue fever case was reported on July 5, and the last one was detected on December 19, with all townships and subdistricts affected. Mosquito monitoring data indicated that both MOI and BI rose rapidly from March to May, and then remained at high levels with fluctuations, and began to decline in October. The dengue fever epidemic was categorized into five distinct phases in Zhongshan, including non⁃epidemic, pre⁃epidemic, early⁃epidemic, peak, and receding stages. During the pre⁃epidemic and early⁃epidemic phases, key measures included enhancing sensitivity of case detection, implementing isolation and treatment of hospitalized cases, and carrying out standardized vector control measures in affected communities. In the peak phase, the strategy shifted towards targeted mosquito control in key communities and clinical rescue and treatment emphasized on “preventing severe cases and deaths”. Among 481 local cases with unknown sources of infections, RT⁃qPCR assay revealed that 68.8% (331/481) were infected with dengue virus typeⅠ and 31.2% (150/481) with type Ⅱ among local dengue fever cases in Zhongshan City in 2024. Phylogenetic analysis revealed two major transmission chains: one originating from imported cases within Guangdong Province around Zhongshan City, and another from cases imported from Malaysia. Late detection of local dengue fever cases contributed to widespread community outbreaks.  Conclusions　The 2024 dengue fever epidemic in Zhongshan City was of considerable scale, which was primarily driven by imported cases from overseas and surrounding regions, leading to local community outbreaks. The epidemic began in early July, increased rapidly during August and September, peaked in October, and subsequently declined, with a trend consistent with the average pattern observed in previous high⁃incidence years. By implementing differentiated control measures tailored to each phase of the epidemic, the local transmission of dengue fever was successfully contained in Zhongshan in 2024. 

Key words: Dengue fever, Epidemiological characteristic, Control measure, Zhongshan City

摘要： 目的　分析2024年中山市登革热流行特征和防控措施，为优化该市登革热防控策略提供参考。方法　自中国疾病预防控制信息系统传染病报告管理平台收集2024年中山市登革热病例信息，采用描述性统计方法对病例特征进行分析。2024年3—12月，于每月中旬对中山市全部23个镇街采用布雷图指数（Breteau index，BI）法和诱蚊诱卵指数（mosquito ovitrap index，MOI）法开展白纹伊蚊密度监测。对2024年中山市登革热疫情不同阶段气候特征、病例报告情况及采取的防控措施进行分析。此外，对感染来源不明的登革热本地病例采用实时荧光定量PCR技术开展登革病毒血清分型，对其中无明显流行病学关联的病例采用Sanger测序法进行登革病毒E基因测序，并基于邻接法构建登革病毒系统发育树，分析登革热疫情主要传播链。结果　2024年中山市累计报告登革热病例952例，其中本地病例879例，境内其他地区输入病例57例，境外输入病例16例，登革热疫情规模为近20年来最大。首例本地病例于7月5日报告，末例本地病例于12月19日报告，疫情波及中山市全部镇街。蚊媒监测数据显示，MOI值和BI值于3—5月快速上升，随后一直在高位波动，至10月开始下降。2024年中山市登革热疫情可划分为非流行期、流行前期、流行早期、高峰期和收尾期5个阶段；在流行前期和流行早期，提升病例监测灵敏度、落实病例住院隔离治疗、规范开展病例所在社区的蚊媒控制为主要措施；进入高峰期后，防控策略逐步调整为以重点社区为主的蚊媒防控，临床救治则以“防重症、防死亡”为目标。481例感染来源不明的本地病例登革病毒血清分型结果显示，2024年中山市感染登革病毒Ⅰ型、Ⅱ型的本地病例分别占68.8%（331/481）、31.2%（150/481）。系统发育树分析结果显示，2024年中山市疫情存在两条主要传播链，分别源自广东省内中山市周边地区输入病例和马来西亚输入病例，本地疫情发现晚，最终形成社区暴发。结论　2024年中山市登革热疫情规模较大，主要由境外及周边地区输入病例引发，进而导致本地社区暴发。疫情从7月初开始，8—9月迅速上升，10月达峰值后逐渐回落，整体趋势与既往高发年份本地病例报告的平均水平较为一致。通过在疫情不同阶段采取差异化防控策略，该市2024年登革热本地疫情得以有效控制。

关键词: 登革热, 流行特征, 防控措施, 中山市