Bell J F, Wikel S K, Hawkins W W, Owen C R
Can J Comp Med. 1978 Jul;42(3):310-5.
Tularemia in range sheep is an occasional cause of severe economic loss from mortality and unthriftiness as well as a hazard to persons in contact with the animals. Epizootics are unpredictable and explosive, therefore, prophylaxis is more practical than therapy. Live vaccine of proven value in man and in beavers was inoculated into mature ewes and elicited antibodies without harm to the sheep. However, challenge of immunity was not possible because virulent Francisella tularensis in large doses did not cause significant mortality in healthy, well managed, unimmunized sheep. Evidence suggests that a complex of stresses such as inclement weather, lambing and concomitant ectoparasitism render sheep more susceptible to tularemia.
绵羊兔热病偶尔会因死亡和生长不良导致严重经济损失，还会对接触动物的人员构成危害。兔热病的流行不可预测且具有爆发性，因此，预防比治疗更具实际意义。已证实对人类和海狸有价值的活疫苗接种到成年母羊体内，可产生抗体且对羊无害。然而，无法对免疫效果进行激发试验，因为大剂量的强毒土拉弗朗西斯菌不会使健康、管理良好且未免疫的绵羊产生显著死亡率。有证据表明，诸如恶劣天气、产羔以及伴随的体外寄生虫感染等一系列应激因素会使绵羊更容易感染兔热病。
