2018年勐腊县城区登革热暴发流行特征与媒介应急监测分析

目的分析2018年勐腊县城区登革热暴发时的流行病学特征、媒介生物学特性等变化情况,为登革热的防控提供依据。方法对勐腊城区疑似登革热病例进行流行病学调查,并开展登革病毒NS1抗原快速检测,首例病例用RT-PCR进行登革病毒核酸检测及型别鉴定;采用背负式吸蚊器法和布雷图指数法分别开展媒介伊蚊成蚊和幼虫的监测;采用三间分布法对疫情特征进行描述,计算成蚊密度和幼虫密度,采用χ^2检验对不同类型孳生阳性率进行比较分析。结果本次疫情共发现病例59例,罹患率为161.38/10万,流行历时77 d。8月份为发病高峰,患者男女比为0.68∶1,以青壮年为主,从事职业以商业服务、离退休和家中待业居多;捕获埃及伊蚊和白纹伊蚊成蚊1 340只,其中埃及伊蚊占80.15%。幼虫监测,13 148户,阳性784户,积水容器13 387个,阳性1 067个,总BI为8.12、总HI为5.96、总CI为7.97%。积水容器类型构成以水桶为主,其次为花瓶。水缸、花瓶、废旧轮胎、竹筒、菜坛、水桶、废弃瓶/罐、其他暂时性容器的伊蚊幼蚊阳性率分别为7.17%、6.07%、24.79%、15.15%、10.12%、6.51%、16.62%、和6.42%。结论 2018年勐腊城区登革热暴发流行的特征与既往比较无明显变化。埃及伊蚊和白纹伊蚊在城区均有分布,以埃及伊蚊为优势蚊种,其种群密度进一步扩大。废旧轮胎、竹筒和水桶等常见伊蚊幼虫孶生地,应及时清除,并开展居民区室内外灭蚊清除工作,同时加大宣传,提高居民的自我防护和家庭防护能力,提升居民参与防控的积极性,以达到群防群控。

Emergency monitoring and analysis of the epidemiological characteristics and vectors of a dengue fever outbreak in Mengla County in 2018

Objective To analyze the epidemiological characteristics of a dengue outbreak and the biological characteristics of vectors in an urban area of Mengla County in 2018 in order to provide evidence for dengue prevention and control. Methods An epidemiological study of suspected cases of dengue fever in Mengla City was conducted,and the dengue virus NS1 antigen was rapidly detected.In positive,the first or second dengue virus serotype was identified using RTPCR.During the peak period of adult mosquito activity(2 hours before sunrise or sunset),adult Aedes mosquitoes were captured in underground garages,parks,islands,hotels,greenhouses,and houses using backpack aspirators and brought back to the laboratory for identification,counting,and recording.The Breteau index(BI)was used to evaluate the scale and risk of a post-dengue outbreak.A household survey indicated that water containers indoors and outdoors were positive for Aedes larvae or pupae.The mosquito larvae were collected and brought back to lab for identification of species with a microscope,counting,and recording.The epidemiological characteristics of this outbreak were described including the geographic,temporal,and population distribution and the density of adult mosquitoes and larvae was determined.The chi-square test was used to compare rates of Aedes detection in different types of containers. Results This outbreak involved a total of 59 patients,with an incidence of 161.38/100,000 and a duration of 77 days.Cases peaked in August.The ratio of male and female patients was 0.68:1.Most patients were younger,and patients ranged in age from 20 to 50 years.In terms of occupation,patients mainly worked in commercial services,were retirees,or were unemployed and living at home.A total of 1,340 adult Aedes mosquitoes were captured(Ae.aegypti:80.15%).An examination of larvae indicated that 784 out of 13,148 households and 1,067 out of 13,387 water containers were positive for Aedes.Overall,the BI was 8.12%,HI was 5.96%,and CI was 7.97%.Aedes mosquitoes were detected in water tanks(7.17%),vases(6.07%),used tires(24.79%),bamboo tubes(15.15%,),vegetable jars(10.12%),buckets(6.51%),discarded bottles/cans(16.62%),and other temporary containers(6.42%).The rate of detection differed significantly(chisquared=267.046,P<0.01). Conclusion The characteristics of dengue fever had not changed markedly during this outbreak.Ae.aegypti and Ae.albopictus were wildly distributed in urban areas.Ae.aegyptiis dominant,and its population is spreading.In the future,prevention and control of dengue fever should continue to not only focus on vector control and particularly deal with Aedes larvae breeding sites both indoors and outdoors in residential areas,such as used tires,bamboo tubes,and buckets,and also prompt resident involvement in control in order to improve their ability to protect themselves and their families.