Cooney Joseph C, Burgdorfer Willy, Painter Martin K, Russell Cynthia L
Northwest Shoals Community College, R O. Box 101 George Wallace Blvd., Muscle Shoals, AL 35662, USA.
J Vector Ecol. 2005 Dec;30(2):171-80.
Studies were conducted over a four-county area of northwest Alabama to determine the association of eastern cottontail rabbits with Dermacentor variabilis, the eastern United States vector of Rocky Mountain spotted fever. A secondary objective was to compare infestations of this tick on rabbits with infestations on commonly encountered rodent species as a means of determining the relative importance of each in the disease transmission cycle. These epidemiologic surveys were conducted in response to reported fatal cases of Rocky Mountain Spotted Fever in two counties of the study area. From 202 eastern cottontail rabbits, 3,956 ticks were collected. Of this total, 79.87% were Haemphysalis leporispalustris, 9.15% Amblyomma americanum, 8.22% Ixodes dentatus, and 2.76% D. variabilis. Only immature stages of D. variabilis were collected from cottontail rabbits. Ticks were collected on rabbits in all months except November, and only one specimen was taken in January. Based on the average number of ticks per host collected in each month, April was the peak month for D. variabilis and I. dentatus. High values for H. leporispalustris also occurred at this time, but even higher values occurred in October and December. The heaviest infestation of A. americanum occurred during the month ofAugust and coincides with the activity period for the larvae of this species. Two hundred sixty-nine of the smaller Rodentia, comprising 13 species, yielded 264 ticks, all D. variabilis, and all but two were immature stages. Five rodent species, Microtus ochragaster Orozomys palustris, Peromyscus gossypinus, Peromyscus leucopus, and Sigmodon hispidus accounted for 95.83% of the ticks collected, and appeared to be preferred hosts for D. variabilis; all five had higher infestation levels per host than did the eastern cottontail rabbit. Data on host relationships in association with seasonal activity are presented.
在阿拉巴马州西北部的四个县开展了研究，以确定东部棉尾兔与变异革蜱（落基山斑疹热在美国东部的传播媒介）之间的关联。次要目标是比较这种蜱在兔身上的寄生情况与在常见啮齿动物物种身上的寄生情况，以此确定每种动物在疾病传播周期中的相对重要性。这些流行病学调查是针对研究区域内两个县报告的落基山斑疹热致死病例而开展的。从201只东部棉尾兔身上采集到3956只蜱。其中，79.87%为沼泽血蜱，9.15%为美洲钝缘蜱，8.22%为具齿硬蜱，2.76%为变异革蜱。从棉尾兔身上采集到的变异革蜱均为未成熟阶段。除11月外，其他月份均在兔身上采集到蜱，1月仅采集到1只标本。根据每月每只宿主采集到的蜱的平均数量，4月是变异革蜱和具齿硬蜱的高峰期。沼泽血蜱在此时的数量也较多，但10月和12月的数量更高。美洲钝缘蜱的寄生高峰出现在8月，与该物种幼虫的活动期一致。269只小型啮齿动物（包括13个物种）身上采集到264只蜱，均为变异革蜱，除2只为成熟阶段外，其余均为未成熟阶段。5种啮齿动物，即奥氏田鼠、沼泽稻鼠、棉鼠、白足鼠和刚毛棉鼠，占采集到的蜱的95.83%，似乎是变异革蜱的偏好宿主；这5种动物每只宿主的寄生水平均高于东部棉尾兔。文中呈现了与季节性活动相关的宿主关系数据。
