Keith L B, Cary J R
Department of Wildlife Ecology, University of Wisconsin, Madison 53706.
J Wildl Dis. 1990 Oct;26(4):427-34. doi: 10.7589/0090-3558-26.4.427.
Prevalence and intensity of the tick, Haemaphysalis leporispalustris, were monitored during 1963 to 1976 in a cyclic snowshoe hare (Lepus americanus) population near Rochester, Alberta, Canada. Prevalence was near zero from December through March, and near 100% among adult hares from May through September. Prevalence among juvenile hares approached 100% by age 2 mo. Intensity peaked for both adults and juveniles during May-June and again in August. Mean intensities were significantly higher among adult males than adult females in 5 of 13 yr, and almost significant in two others. Tick intensities were lowest during 3 yr, 1969 to 1971, when hare densities were highest. Tick intensities in spring were correlated with intensities the previous fall. Survival of marked adult and juvenile hares was unrelated to intensities of infestation. Mean numbers of corpora lutea and embryos tended to be lower among adult females with heavy tick infestations, and intra-uterine losses rose steadily from about 3 to 13% as tick intensities increased from none to heavy. Comparison of average tick intensities on adults 1-, 2-, and greater than or equal to 3-yr-old yielded no evidence of increased immunity with age.
1963年至1976年期间，在加拿大艾伯塔省罗切斯特附近一个呈周期性变化的白靴兔（美洲兔）种群中，对沼泽血蜱的患病率和感染强度进行了监测。12月至次年3月期间患病率接近零，5月至9月成年野兔的患病率接近100%。2月龄幼兔的患病率接近100%。成年兔和幼兔的感染强度在5月至6月以及8月达到峰值。在13年中的5年里，成年雄兔的平均感染强度显著高于成年雌兔，另外两年也几乎有显著差异。1969年至1971年这3年野兔密度最高时，蜱的感染强度最低。春季蜱的感染强度与前一年秋季的感染强度相关。标记的成年兔和幼兔的存活率与感染强度无关。蜱虫大量寄生的成年雌兔的黄体和胚胎平均数往往较低，随着蜱虫感染强度从无到有增加，子宫内损失率从约3%稳步上升至13%。对1岁、2岁以及大于或等于3岁成年兔的平均蜱感染强度进行比较，没有发现随年龄增长免疫力增强的证据。
