Day J F, Curtis G A
Florida Medical Entomology Laboratory, University of Florida, Vero Beach 32962, USA.
J Med Entomol. 1999 Mar;36(2):176-81. doi: 10.1093/jmedent/36.2.176.
A widespread epidemic of St. Louis encephalitis (SLE) virus was reported from central Florida from late July through December 1990 with 226 clinical cases and 11 deaths in humans. The abundance of blood-fed and gravid Culex nigripalpus Theobald females, the vector of SLE in Florida, was monitored at a resting site in Indian River County, FL, for the 3 yr before the epidemic, the epidemic year, and for 1 yr following the epidemic. Each study year was divided into four 3-mo periods that depict the subtropical SLE transmission cycle; a January-March maintenance phase, an April-June amplification phase, a July-September early transmission phase, and an October-December late transmission phase. The abundance of blood-fed and gravid females was significantly greater during the amplification, early transmission, and late transmission phases of the 1990 SLE epidemic when compared with the 3 pre-epidemic years. Throughout the study, Cx. nigripalpus blood feeding and oviposition was driven by epic (> 50 mm) rainfall events. The abundance of gravid females decreased, whereas the number of blood-fed females increased following heavy rainfalls. Epizootic and epidemic transmission of SLE to sentinel chickens and humans in Indian River County was greatest immediately following heavy rainfalls that synchronized Cx. nigripalpus oviposition and blood feeding.
据报道，1990年7月下旬至12月，佛罗里达州中部爆发了圣路易斯脑炎（SLE）病毒的广泛流行，出现了226例临床病例，11人死亡。在疫情爆发前3年、疫情当年以及疫情后的1年里，对佛罗里达州印度河县一个休息点的黑胸库蚊（SLE在佛罗里达州的传播媒介）中吸食过血的雌蚊和孕蚊数量进行了监测。每个研究年份分为四个3个月的时间段，以描述亚热带地区的SLE传播周期：1月至3月的维持阶段、4月至6月的扩增阶段、7月至9月的早期传播阶段以及10月至12月的晚期传播阶段。与疫情爆发前的3年相比，1990年SLE疫情的扩增、早期传播和晚期传播阶段，吸食过血的雌蚊和孕蚊数量显著更多。在整个研究过程中，黑胸库蚊的吸血和产卵受到暴雨（降雨量超过50毫米）事件的驱动。暴雨过后，孕蚊数量减少，而吸食过血的雌蚊数量增加。在同步了黑胸库蚊产卵和吸血行为的暴雨过后，印度河县SLE在哨兵鸡和人类中的流行和爆发性传播最为严重。
