Immunisation against Theileria parva in eastern Zambia: influence of maternal antibodies and demonstration of the carrier status.
Immunisation against Theileria parva in eastern Zambia: influence of maternal antibodies and demonstration of the carrier status.
复制标题
赞比亚东部针对细小泰勒虫的免疫：母体抗体的影响和携带者状态的证明。
DOI：
10.1016/s0304-4017(02)00314-x
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发表时间：
2002
影响因子：
2.6
通讯作者：
D. Berkvens
中科院分区：
文献类型：
--
作者：
T. Marcotty;J. Brandt;M. Billiouw;G. Chaka;B. Losson;D. Berkvens
在赞比亚的东部省，通过感染和治疗方法（I & T）对小牛进行免疫接种已被广泛用于控制东海岸热（ECF），这是一种原生动物蜱传疾病。本文介绍了一个现场纵向研究的结果，其中包括共148安戈尼小牛。在对ECF进行免疫接种后，对它们进行了一个完整的雨季监测，与小泰勒虫病媒（蜱Rhipicephalus approxulatus）的主要活动高峰期一致。免疫不良（I & T免疫产生的急性反应）、血清转化和死亡率是记录的参数。母源抗体对这些参数的影响进行了分析，并在实验条件下对两头小牛进行了研究。免疫前，幼龄小牛的血清阳性率高于老龄动物（母体抗体），但其免疫后血清阳性率较低。没有证据表明其免疫保护较弱，但这表明免疫后血清转化可能不是监测小牛免疫效力的可靠工具。在实验条件下对三头牛进行免疫接种后牛的带菌者状态研究，而在田间，使用蜱虫负荷与T.幼鲸与幼鲸接触。幼虫和若虫的能力。apapriculatus对T.评估了从携带者身上传播parva并在换羽后将其传播给初生动物的可能性。结果表明，两种虫态均能传播临床和致死性ECF，但T。小孢子虫感染率远低于成人，证实了成人在地方性条件下ECF传播中的主要作用。从ECF峰对应于成虫R峰的现场获得了类似的结果。附着活动然而，蜱的感染率在田间比在实验条件下低得多，这表明它们中的一个重要部分以替代宿主为食。老蜱似乎失去了部分传染性。
Immunisation of calves by the infection and treatment method (I & T) has been extensively used in the eastern province of Zambia to control East Coast fever (ECF), a protozoan tick-borne disease. This paper presents the results of a field longitudinal study, which included a total of 148 Angoni calves. After immunisation against ECF, they were monitored for a full rainy season, coinciding with the main peak of activity of the vector of Theileria parva, the tick Rhipicephalus appendiculatus. Dysimmunisation (acute reaction generated by I & T immunisation), seroconversion and mortality are among the parameters recorded. The effect of maternal antibodies on these parameters was analysed and also studied in experimental conditions on two calves. Before immunisation, young calves had a higher seroprevalence than older animals (maternal antibodies) but their post-immunisation seroprevalence was lower. There was no evidence that their immunoprotection was weaker but this indicates that the post-immunisation seroconversion is probably not a reliable tool to monitor the efficacy of calf immunisation. The carrier state of cattle after immunisation was investigated in experimental conditions on three bovines whereas in the field, the infection prevalence in the ticks was estimated using the relation between the tick burden and the T. parva contacts with the calves. The ability of larval and nymphal R. appendiculatus ticks to pick-up T. parva from carriers and to transmit it to naı̈ve animals after moulting was assessed. It was found that both instars are able to transmit clinical and lethal ECF but that the prevalence of T. parva infection in nymphs is much lower than in adults, confirming the primary role of adults in the transmission of ECF in endemic conditions. Similar results were obtained from the field whereby the ECF peak corresponds with the peak of adult R. appendiculatus activity. The infection prevalence in the ticks was however much lower in the field than in experimental conditions indicating that an important proportion of them feed on alternative hosts. Old ticks seemed to have lost part of their infectivity.