腺鼠疫周期性地发生在黑尾旱獭(Cy-nomys Ludovicianus Ord)种群中,在其大部分分布区都有流行。黑尾旱獭中,一次动物流行病期间的死亡率常高于99%。旱獭鼠疫动物流行病通常发生于比较孤立或人烟稀少的地区,人类感染的危险性很小;然而,过去20年间,美国西部各州,特别是近市中 The bubonic plague occurs periodically in the population of Cy-nomys Ludovicianus Ord, and is endemic in most of its distribution. In black tailed marmot, the mortality rate during a single animal epidemic is often higher than 99%. The malaria epidemic usually occurs in relatively isolated or sparsely populated areas and the risk of human infection is minimal; however, over the past two decades, western United States, particularly in the immediate vicinity