University of Florida, Institute of Food and Agricultural Sciences, Florida Medical Entomology Laboratory, 200 9th St. SE, Vero Beach, FL 32962, USA.
J Med Entomol. 2009 Nov;46(6):1498-506. doi: 10.1603/033.046.0638.
Mosquito-borne arboviral epidemics tend to strike without warning. The driving force for these epidemics is a combination of biotic (vector, amplification host, and virus) and abiotic (meteorological conditions, especially rainfall and temperature) factors. Abiotic factors that facilitate the synchronization and interaction of vector and amplification host populations favor epidemic amplification and transmission. In Florida, epidemics of St. Louis encephalitis (SLE) virus (family Flaviviridae, genus Flavivirus, SLEV) have been preceded by major freezes one or two winters before the onset of human cases. Here, we analyze the relationship between severe winter freezes and epidemic SLEV transmission in peninsular Florida and show that there is a significant relationship between the transmission of SLEV and these severe freezes. We propose that by killing cold-sensitive understory vegetation in the mid-peninsular region of Florida, freezes enhance the reproductive success of ground-feeding avian amplification hosts, especially mourning doves and common grackles. In conjunction with other appropriate environmental signals, increased avian reproductive success may enhance SLEV and West Nile (WN) virus amplification and result in SLE and WN epidemics during years when all of the biological cycles are properly synchronized. The knowledge that winter freezes in Florida may enhance the amplification and epidemic transmission of SLE and WN viruses facilitates arboviral tracking and prediction of human risk of SLE and WN infection during the transmission season.
蚊媒虫媒病毒病疫情往往突然爆发。这些疫情的驱动力是生物因素（媒介、扩增宿主和病毒）和非生物因素（气象条件，特别是降雨和温度）的结合。有利于媒介和扩增宿主种群同步和相互作用的非生物因素有利于疫情的放大和传播。在佛罗里达州，圣路易斯脑炎病毒（SLE 病毒）（黄病毒科，黄病毒属，SLEV）疫情的爆发往往发生在人类病例出现前一到两个冬季的严重冰冻之后。在这里，我们分析了严重冬季冰冻与佛罗里达州半岛地区流行的 SLEV 传播之间的关系，并表明 SLEV 的传播与这些严重冰冻之间存在显著关系。我们提出，冰冻会杀死佛罗里达州半岛中部地区对寒冷敏感的下层植被，从而增强了地面觅食的鸟类扩增宿主的繁殖成功率，尤其是哀悼鸽和普通八哥。与其他适当的环境信号相结合，鸟类繁殖成功率的提高可能会增强 SLEV 和西尼罗河（WN）病毒的扩增，从而导致在所有生物周期都得到适当同步的年份出现 SLE 和 WN 疫情。了解到佛罗里达州的冬季冰冻可能会增强 SLE 和 WN 病毒的扩增和流行传播，有助于跟踪虫媒病毒并预测人类在传播季节感染 SLE 和 WN 的风险。
