摘要
本文以１．２５×１０７Ｃ．ｂａｉｌｅｙｉ卵囊的剂量人工经口感染３～７５日龄雏鸡，通过Ｃ．ｂａｉｌｅｙｉ卵囊排出规律和临床发病情况的观察，研究了雏鸡对Ｃ．ｂａｉｌｅｙｉ感染的年龄免疫现象。结果表明，３～７５日龄雏鸡均能感染Ｃ．ｂａｉｌｅｙｉ；３～１０日龄雏鸡易感性高，感染后排出印囊的量大，排出印囊的时间长，持续到感染后第２０天；２０日龄以上的雏鸡随着年龄的增长，感染后排出卵囊的量逐渐减少，排出印囊的时间缩短，仅持续到感染后第１５天。５０日龄以下的雏鸡感染后排出卵囊的量明显地高于５０日龄以上的雏鸡，５０～７５日龄的雏鸡易感性很低，排出卵囊的量趋于恒定地极少量排出。从而揭示随着雏鸡年龄增长免疫系统发育逐步完善，感染后排出印囊的量逐渐减少、排出卵囊的时间缩短、对Ｃ．ｂａｉｌｅｙｉ的易感性逐渐降低的规律。首次实验证实Ｃ．ｂａｉｌｅｙｉ作为一种原发性病原主要侵害５０日龄以下的雏鸡，尤其是１０日龄以内的雏鸡易感性最高，发病和死亡主要见于１０日龄以内感染的雏鸡。
Age Immunity Phenomenon of 3-75 days-old chickens against C. baileyi (1.25 ×107 oocysts for each chicken) was studied by the observations of oocyst excretion and clinical illness. The experiment showed that all the chickens can be infected with C. baileyi. Chickens of 3-10 days-old had a high susceptibility to C. baileyi when there were large number of oocysts found in faeces with a long patent period that lasted to 20-th day after infection. Chickens of 20 days-old and over it. when the age became larger and larger. showed a gradually decrease in oocyst number of faeces and a shorter patent period that only lasted to 15-th dab after infection. The number of oocyst excretion was much larger in chickens under the age of 50 days than that in chickens over the age of 50 days. The chickens of 50-75 days-old had very low susceptibility to C. baileyi when there were few oocysts nearly in same number found in faeces.The above-mentioned results indicated that the oocyst excretion number. patent period and the susceptibility to C. baileyi were gradually reduced when the chickens became old and their immunity system well developed gradually. The experiment confirmed first in the world that C.baileyi had high infectivity to the chiCkens under 50 days-old as a premier pathogeny (especially. there was the highest infectivity in chickens under 10 days-old). Clinical cryptosporidiosis and death were mainly occurred in chickens under 10 days-old with experimental infection.
出处
《中国兽医寄生虫病》
1994年第4期11-15,共5页
Chinese Journal of Veterinary Parasitology
