Sherman D M, Bray B, Gay J M, Bates F
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul 55108.
Am J Vet Res. 1989 Apr;50(4):525-30.
Concurrent bacteriologic culture of feces and agar gel immunodiffusion (AGID) testing was performed on all cows and bred heifers over 14 months old in 10 dairy herds during a 32-month period to determine the effectiveness of the AGID test for the detection of subclinical paratuberculosis. Herds were sampled 5 times and, when possible, culled animals were tested again at slaughter. During 5 herd-wide samplings, Mycobacterium paratuberculosis was isolated from 139 fecal specimens obtained from 109 cattle. Results of the AGID test were simultaneously positive 40 of 139 times (28.8%). Thirty-six of the 109 cattle (33.0%) determined to be infected had a positive AGID test result at some point during the 5 herd-wide samplings. When results of tests performed at time of slaughter were included, 117 cattle were identified as infected by culture methods; 55 of these (47.0%) were AGID test-positive at some point during the study. The upper limit of the maximal false-positive rate for the AGID test was 2.1%. On the basis of colony counts from cultures, subclinically infected cows shedding higher numbers of M paratuberculosis in their feces were more likely to have positive AGID test results (P less than 0.0001). In known infected cattle, neither the culture nor AGID test results were consistently positive on repeated testing. Of 48 official calfhood paratuberculosis vaccinates tested as adults, 3 had positive AGID test results and in 1 of these, M paratuberculosis was also isolated from the feces, indicating that the rate of false-positive AGID test results in calfhood vaccinates is low.
在32个月的时间里，对10个奶牛场中所有14个月以上的奶牛和经产小母牛进行了粪便的同步细菌培养和琼脂凝胶免疫扩散（AGID）检测，以确定AGID检测对亚临床型副结核病的检测效果。对牛群进行了5次采样，并且在可能的情况下，对淘汰动物在屠宰时再次进行检测。在5次全群采样期间，从109头牛的139份粪便样本中分离出了副结核分枝杆菌。AGID检测结果在139次中有40次（28.8%）同时呈阳性。在确定感染的109头牛中，有36头（33.0%）在5次全群采样期间的某个时间点AGID检测结果呈阳性。当纳入屠宰时进行的检测结果时，通过培养方法确定有117头牛感染；其中55头（47.0%）在研究期间的某个时间点AGID检测呈阳性。AGID检测的最大假阳性率上限为2.1%。根据培养物中的菌落计数，粪便中排出较多副结核分枝杆菌的亚临床感染奶牛更有可能AGID检测结果呈阳性（P<0.0001）。在已知感染的牛中，重复检测时培养和AGID检测结果都并非始终呈阳性。在作为成年牛进行检测的48头官方犊牛期副结核病疫苗接种牛中，有3头AGID检测结果呈阳性，其中1头的粪便中也分离出了副结核分枝杆菌，这表明犊牛期疫苗接种牛中AGID检测结果的假阳性率较低。
