Crawford R P, Adams L G, Williams J D
Department of Veterinary Public Health, College of Veterinary Medicine, Texas A&M University, College Station 77840.
Am J Vet Res. 1988 Jul;49(7):1037-9.
Heifers injected with 10(8) (n = 40), 10(9) (n = 39), or 10(10) (n = 39) colony-forming units of Brucella abortus strain 19 were conjunctivally exposed to 10(7) colony-forming units of strain 2308 during gestation. At parturition, milk from each quarter of the udder, a piece of placenta, and 2 swab specimens of the uterus from the dam plus a swab specimen of the rectum from each calf were cultured for Brucella. If the calf was dead or died, additional specimens of lung, stomach contents, and a mediastinal lymph node also were cultured. Days in gestation was determined for each heifer, using data from rectal palpation after breeding and crown-rump length and weight of calf at parturition, with the median value used for data analysis. In each vaccine dosage group, the proportion (%) of heifers developing brucellosis increased as days in gestation at exposure increased. Strain 2308 was isolated from 3 (11%) of 26, 16 (25%) of 64, and 18 (64%) of 28 heifers that were grouped as less than 121, 121 to 150, and greater than 150 days in gestation at time of exposure, respectively. Thirty-two (86%) of the 37 infected heifers were less than 260 days in gestation at parturition, and calves were premature. Heifers with premature calves were more likely to be infected, and tissues were more likely to yield multiple isolations of strain 2308, regardless of days in gestation at exposure or of days after exposure to parturition. Days after exposure to premature parturition of infected heifers ranged from 35 to 110.
给妊娠期间的小母牛结膜接种10⁸（n = 40）、10⁹（n = 39）或10¹⁰（n = 39）个流产布鲁氏菌19菌株的菌落形成单位，然后结膜暴露于10⁷个2308菌株的菌落形成单位。分娩时，对每头小母牛每个乳房象限的乳汁、一块胎盘、来自母牛子宫的2个拭子标本以及每头小牛直肠的一个拭子标本进行布鲁氏菌培养。如果小牛死亡，还要对肺、胃内容物和一个纵隔淋巴结的额外标本进行培养。利用配种后直肠触诊数据以及分娩时小牛的顶臀长度和体重确定每头小母牛的妊娠天数，取中位数进行数据分析。在每个疫苗剂量组中，随着暴露时妊娠天数的增加，患布鲁氏菌病的小母牛比例（%）也增加。在暴露时妊娠天数分别少于121天、121至150天和大于150天的26头、64头和28头小母牛中，分别有3头（11%）、16头（25%）和18头（64%）分离出2308菌株。37头受感染的小母牛中有32头（86%）分娩时妊娠天数少于260天，小牛早产。早产小牛的小母牛更易感染，且组织更易多次分离出2308菌株，无论暴露时的妊娠天数或暴露至分娩的天数如何。受感染小母牛暴露至早产的天数为35至110天。
