Tripp Daniel W, Gage Kenneth L, Montenieri John A, Antolin Michael F
Department of Biology and Shortgrass Steppe Long-Term Ecological Project, Colorado State University, Fort Collins, Colorado 80523, USA.
Vector Borne Zoonotic Dis. 2009 Jun;9(3):313-21. doi: 10.1089/vbz.2008.0194.
Black-tailed prairie dogs (Cynomys ludovicianus) on the Great Plains of the United States are highly susceptible to plague, caused by the bacterium Yersinia pestis, with mortality on towns during plague epizootics often approaching 100%. The ability of flea-borne transmission to sustain disease spread has been questioned because of inefficiency of flea vectors. However, even with low individual efficiency, overall transmission can be increased if flea abundance (the number of fleas on hosts) increases. Changes in flea abundance on hosts during plague outbreaks were recorded during a large-scale study of plague outbreaks in prairie dogs in north central Colorado during 3 years (2004-2007). Fleas were collected from live-trapped black-tailed prairie dogs before and during plague epizootics and tested by PCR for the presence of Y. pestis. The predominant fleas were two prairie dog specialists (Oropsylla hirsuta and Oropsylla tuberculata cynomuris), and a generalist flea species (Pulex simulans) was also recorded from numerous mammals in the area. The three species differ in seasonal abundance, with greatest abundance in spring (February and March) and fall (September and October). Flea abundance and infestation intensity increased during epizootics and were highest on prairie dogs with Y. pestis-infected fleas. Seasonal occurrence of epizootics among black-tailed prairie dogs was found to coincide with seasonal peaks in flea abundance. Concentration of infected fleas on surviving animals may account for rapid spread of plague during epizootics. In particular, the role of the generalist flea P. simulans was previously underappreciated.
美国大平原上的黑尾土拨鼠（Cynomys ludovicianus）对由鼠疫耶尔森菌引起的鼠疫高度易感，在鼠疫 epizootics 期间，城镇中的死亡率通常接近 100%。由于跳蚤媒介效率低下，经跳蚤传播维持疾病传播的能力受到质疑。然而，即使个体效率较低，如果跳蚤丰度（宿主身上的跳蚤数量）增加，总体传播也会增加。在 2004 年至 2007 年的 3 年期间，对科罗拉多州中北部草原犬鼠鼠疫疫情进行大规模研究时，记录了鼠疫疫情期间宿主身上跳蚤丰度的变化。在鼠疫 epizootics 之前和期间，从活体诱捕的黑尾土拨鼠身上收集跳蚤，并通过 PCR 检测鼠疫耶尔森菌的存在。主要的跳蚤是两种草原犬鼠特有的跳蚤（多毛山蚤和瘤山蚤 cynomuris），并且还从该地区的许多哺乳动物身上记录到一种普通跳蚤物种（印鼠客蚤）。这三个物种的季节性丰度不同，春季（2 月和 3 月）和秋季（9 月和 10 月）丰度最高。在 epizootics 期间，跳蚤丰度和感染强度增加，并且在感染了鼠疫耶尔森菌跳蚤的草原犬鼠身上最高。发现黑尾土拨鼠中 epizootics 的季节性发生与跳蚤丰度的季节性峰值一致。感染跳蚤在存活动物上的集中可能解释了 epizootics 期间鼠疫的快速传播。特别是，普通跳蚤印鼠客蚤的作用以前未得到充分认识。
