目的 为降低中山市登革热暴发风险,建立登革热分级预警应对体系并评价预警效果。方法 查阅文献、结合中山市1990－2007年登革热媒介监测、病例监测数据,建立登革热分级预警应对体系;2008－2011年在全市范围实施登革热分级预警;收集1990－2011年中山市登革热暴发数据,通过比较预警体系建立前后登革热暴发规模,评估预警体系。结果 在诱蚊诱卵阳性指数、病例和月份3个指标的基础上,建立中山市0～4级登革热预警体系,其对应暴发的可能性分别为几乎无、很小、可能、危险和暴发。2008－2011年,预警体系共发出可能预警信号5次,危险预警信号2次,暴发预警信号1次。2008－2011年仅发生一起登革热暴发疫情,涉及3例患者,罹患率为1.20%(3/250),持续20 d。1990－2007年,共发生7起暴发疫情,涉及病例数14～195例(中位数37例),罹患率为0.84%～14.88%(中位数3.81%),持续16～64 d(中位数42 d)。结论 分级预警应对体系建立后,2008－2011年中山市登革热暴发规模与1990－2007年相比显著降低。分级预警应对体系在降低中山市登革热暴发风险中发挥了重要作用。

Objective To establish a graded early warning system for dengue fever and assess its effect of early warning and to reduce the risk of dengue fever outbreak in Zhongshan, China. Methods A graded early warning system for dengue fever was established based on relevant literature and the data of vector surveillance and human case surveillance in Zhongshan from 1990 to 2007. The system was used for graded early warning in Zhongshan from 2008 to 2011. The outbreak scales before and after the system was established were compared based on the data on dengue fever outbreaks in Zhongshan from 1990 to 2011 to assess the graded early warning system. Results The graded early warning system for dengue fever was established according to the following indices: mosquito and oviposition positive index (MOI), human cases, and month of year; the system divided the probability of dengue fever outbreak into 5 grades, i.e., 0: almost no probability; 1: little probability; 2: probability; 3: high probability; 4: outbreak. The system sent grade 2 early warning signals 5 times, grade 3 early warning signals twice, and grade 4 early warning signals once from 2008 to 2011. From 2008 to 2011, there was only one outbreak of dengue fever involving 3 (1.20%) of 250 persons, which lasted for 20 d; from 1990 to 2007, there were 7 outbreaks of dengue fever involving 14-195 (median, 37) (0.84%-14.88%, median 3.81%) of all individuals, which lasted for 16-64 d (median, 42 d). Conclusion After the graded early warning system for dengue fever was established, the outbreak scale of dengue fever decreased significantly during 2008-2011, as compared with those during 1990-2007. The graded early warning system plays an important role in reducing the risk of dengue fever outbreak in Zhongshan.