Peregrine A S, Ogunyemi O, Whitelaw D D, Holmes P H, Moloo S K, Hirumi H, Urquhart G M, Murray M
International Laboratory for Research on Animal Diseases, Nairobi, Kenya.
Vet Parasitol. 1988 Apr;28(1-2):53-64. doi: 10.1016/0304-4017(88)90018-0.
The duration of a single isometamidium chloride (Samorin) prophylactic treatment against Trypanosoma congolense ILNat. 3.1 and T. congolense IL 285 was examined in 24 Boran steers with regard to (1) the dose of drug, (2) the level of metacyclic challenge and (3) the influence of infection with an unrelated serodeme at the time of treatment. The cattle were repeatedly challenged at monthly intervals between 2 and 7 months following treatment, either by five infected Glossina morsitans centralis or by intradermal inoculation of 5 X 10(3) or 5 X 10(5) in vitro-derived metacyclic trypanosomes. A dose of 1 mg kg-1 afforded complete protection for 4 months and 0.5 mg kg-1 for 3 months against the two T. congolense serodemes examined, irrespective of the method or weight of challenge. In another group of cattle, which had an established infection at the time of treatment, the duration of chemoprophylaxis against an unrelated serodeme was the same as the other groups which had no previous experience of trypanosome infection. Antibodies to metacyclics did not appear in any of the cattle as long as the chemoprophylaxis was effective. An exception to this was the group challenged with 5 X 10(5) in vitro-derived metacyclic parasites, in which low antibody titres were detected. In all cases these proved to be non-protective. It was concluded that, under the experimental conditions employed, (1) there was a direct relationship between drug dosage and the duration of chemoprophylaxis, (2) the weight of metacyclic challenge did not affect the duration of chemoprophylaxis and (3) when used to treat an existing infection, isometamidium chloride exerted the same degree of chemoprophylactic activity.
在24头博拉安公牛中，研究了单剂量氯异美啶（Samorin）对刚果锥虫ILNat. 3.1和刚果锥虫IL 285的预防性治疗持续时间，涉及以下方面：（1）药物剂量；（2）循环后期锥虫攻击水平；（3）治疗时感染无关血清型的影响。在治疗后的2至7个月期间，每月对牛进行重复攻击，攻击方式为五只感染的中喙采采蝇，或皮内接种5×10³或5×10⁵体外培养的循环后期锥虫。无论攻击方法或攻击量如何，1 mg kg⁻¹的剂量对所检测的两种刚果锥虫血清型提供了4个月的完全保护，0.5 mg kg⁻¹的剂量提供了3个月的完全保护。在另一组治疗时已有感染的牛中，针对无关血清型的化学预防持续时间与之前无锥虫感染经历的其他组相同。只要化学预防有效，任何牛都未出现针对循环后期锥虫的抗体。例外情况是用5×10⁵体外培养的循环后期寄生虫攻击的组，其中检测到低抗体滴度。在所有情况下，这些抗体均无保护作用。得出的结论是，在所采用的实验条件下：（1）药物剂量与化学预防持续时间之间存在直接关系；（2）循环后期锥虫攻击量不影响化学预防持续时间；（3）氯异美啶用于治疗现有感染时，发挥相同程度的化学预防活性。
