Epidemiological aspects of the use of live anticoccidial vaccines for chickens
Epidemiological aspects of the use of live anticoccidial vaccines for chickens
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DOI：
10.1016/s0020-7519(98)00066-6
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发表时间：
1998-07-01
影响因子：
4
通讯作者：
Williams, RB
中科院分区：
文献类型：
--
作者：
Williams, RB
本文综述了商品鸡球虫病的流行病学（流行病学），重点介绍了活疫苗使用的影响。调查显示，鸡球虫七种有效种（无膝艾美耳球虫、布氏艾美耳球虫、大艾美耳球虫、密氏艾美耳球虫、网状艾美耳球虫、提前艾美耳球虫和柔嫩艾美耳球虫）普遍存在。所有的物种都有不同程度的致病性。本文报道了针状芽孢杆菌、密支性芽孢杆菌和提前芽孢杆菌致病性的新结果。除非被鸡吞食，否则鸡舍垃圾中的卵囊可在约3周后死亡。卵囊的产孢在干燥的凋落物中比在潮湿的凋落物中更好。无论是否有孢子，高达20%的被摄入的卵囊可能会完好无损地通过鸡的肠道。排出的带有孢子的卵囊可立即被重新摄入，从而引发感染；未产孢子的卵囊在穿过肠道后仍能产孢子。这七个品种在商业禽群中出现的时间不同；因此，可为饲养标准肉鸡至多6周或种畜设计特殊疫苗。疫苗中的衰减、早熟艾美耳球粒系具有较低的生殖潜力，因此避免拥挤，发育最佳，并以最小的组织损伤刺激免疫反应。艾美耳球虫物种之间的交叉免疫可能微乎其微。鸡的免疫状态和每一种鸡的卵囊排泄之间存在着相互作用，确保了产仔鸡免疫反应的持续刺激。Paracox（TM）疫苗包含所有7种艾美耳球虫，在这里显示的是单独刺激对每一种艾美耳球虫的免疫。接种弓形虫后第1周窝产中总卵囊积累在2-4周出现一个小峰值，然后在4-7周出现一个更高的峰值，然后迅速减弱。减毒的药物敏感疫苗卵囊可能与相应的野生物种杂交，从而降低了当地种群的毒力和耐药性。抗球虫疫苗可能无法诱导因应激源（包括某些病毒性疾病）导致免疫能力降低的鸡产生完全免疫。标准肉鸡活疫苗的未来开发有望在相对较短的时间内完成。通过与活疫苗轮流使用，抗球虫药物的有效寿命可能会延长。(C) 1998澳大利亚寄生虫学学会。Elsevier Science Ltd.出版。
This review addresses the epidemiology (epizootiology) of coccidiosis in commercial chickens with emphasis on the effects on the use of live vaccines. Surveys suggest that all seven valid species of chicken coccidia (Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox and Eimeria tenella) are ubiquitous. All species are pathogenic to various extents. New results are presented on the pathogenicities of E. acervulina, E. mitis and E. praecox. Unless ingested by chickens, oocysts in poultry-house litter may die after about 3 weeks. Oocyst sporulation may be better in drier, rather than wetter, litter. Whether sporulated or not, up to 20% of ingested oocysts may pass undamaged through a chicken's intestine. The excreted, sporulated oocysts can be immediately reingested to initiate an infection; the unsporulated oocysts can still sporulate after passing through the intestine. The seven species differ in their times of appearance in commercial flocks; hence particular vaccines may be designed for rearing standard broilers for up to about 6 weeks or for breeding stock. Attenuated, precocious lines of Eimeria in vaccines have low reproductive potentials, thus avoiding crowding, developing optimally, and stimulating immune responses with minimal tissue damage. Cross-immunity between Eimeria species is probably minimal. There is reciprocity between the immune status of chickens and their excretion of oocysts for each species, ensuring continual stimulation of immune responses in birds on litter. Paracox(TM) vaccine, comprising all seven Eimeria species, is shown here to stimulate immunity to each of them independently. Total oocyst accumulation in litter following Paracox(TM) vaccination at 1 week comprises a small peak of vaccinal oocysts at 2-4 weeks, then a higher peak of the local virulent population at 4-7 weeks, which rapidly wanes. The attenuated drug-sensitive vaccinal oocysts probably interbreed with the corresponding wild species, reducing both virulence and drug-resistance in the local population. Anticoccidial vaccines may not induce complete immunity in chickens with lowered immunocompetence due to stressors, including certain viral diseases. Future development of live vaccines for standard broilers may be expected in the relatively short term. The useful lives of anticoccidial drugs might be extended by rotating them with live vaccines. (C) 1998 Australian Society for Parasitology. Published by Elsevier Science Ltd.