Martinez T A, Meltzer M I, Perry B D, Burridge M J, Mahan S M
Department of Pathobiology, College of Veterinary Medicine, University of Florida, Gainesville 32611, USA.
Prev Vet Med. 1999 Jul 20;41(2-3):105-18. doi: 10.1016/s0167-5877(99)00039-2.
An alternative control option for heartwater (Cowdria ruminantium infection) is the establishment and maintenance of endemic stability which would lessen the existing dependence on acaricides. In an endemically stable state, animals become infected by vaccination or natural challenge at an early age, following which the immunity so created is boosted by continuing tick challenge. In this study, growth rates, health and hematological parameters were monitored at regular intervals for lambs born to two matched groups of ewes until weaning at 4 mo of age. One group of ewes was infected multiple times with Cowdria ruminantium; the other group remained uninfected. The overall mean leucocyte count of lambs born to infected ewes was significantly lower than that of lambs born to uninfected ewes (P=0.04). However, there were few other significant differences in the other hematological data between the two groups. The mean birth weight of single lambs born to uninfected ewes (4.6 kg) was significantly higher than the mean birth weight of single lambs born to infected ewes (4.4 kg) (P=0.02). Trends in milk consumption and growth rates were similar for the two groups, with few significant differences detected. Likewise, there were no significant differences in the incidences of health problems or pre-weaning mortalities between the two groups of lambs. The results of this study indicate that there is no detectable effect on productivity of pre-weaning lambs when their dams are carriers of C. ruminantium--a situation likely to occur in an endemically stable state. Hence, maintenance of endemic stability would be a suitable control option for heartwater.
牛心水病（反刍动物考德里氏体感染）的另一种控制方法是建立并维持地方病稳定状态，这将减少目前对杀螨剂的依赖。在地方病稳定状态下，动物在幼年时通过接种疫苗或自然感染而被感染，此后，持续的蜱虫叮咬会增强由此产生的免疫力。在本研究中，对两组匹配的母羊所生羔羊的生长速度、健康状况和血液学参数进行定期监测，直至4月龄断奶。一组母羊多次感染反刍动物考德里氏体；另一组未感染。感染母羊所生羔羊的总体平均白细胞计数显著低于未感染母羊所生羔羊（P = 0.04）。然而，两组之间的其他血液学数据几乎没有其他显著差异。未感染母羊所生单羔的平均出生体重（4.6千克）显著高于感染母羊所生单羔的平均出生体重（4.4千克）（P = 0.02）。两组的牛奶摄入量和生长速度趋势相似，几乎没有检测到显著差异。同样，两组羔羊的健康问题发生率或断奶前死亡率也没有显著差异。本研究结果表明，当母羊是反刍动物考德里氏体携带者时，对断奶前羔羊的生产力没有可检测到的影响——这种情况很可能发生在地方病稳定状态下。因此，维持地方病稳定状态将是控制牛心水病的合适方法。
