Centre for Veterinary Epidemiology and Risk Analysis, UCD School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
Ir Vet J. 2009 Mar 1;62(3):182-90. doi: 10.1186/2046-0481-62-3-182.
Since 1998, there has been a steady decline in herd restrictions and de-populations in Ireland due to bovine brucellosis. There is concern that the interpretation of laboratory results may become increasingly problematic, as brucellosis prevalence falls in Ireland. Therefore, the purpose of the current study was to evaluate the infection status of Irish herds and animals with inconclusive serological evidence of bovine brucellosis. During 12 months from September 1, 2004, laboratory and observational epidemiological data were collected from all Irish herds where animal testing identified at least one animal with a complement fixation test (CFT) reading greater than zero and/or a positive result to the indirect enzyme-linked immunosorbent assay (iELISA). Due to the observational nature of the study, we have robust estimates of the relative, but not the absolute, performance of the CFT, iELISA and brucellin skin test (BST). Herds were divided into three categories (Group A, B or C) on the basis of test results at initial assessment. A total of 639 herds were enrolled into the study, and observed for at least two years following enrolment. A rising CFT titre, with a CFT reading of 111 International CFT Units (IU) or greater at the subsequent blood test, was generally associated with herds where other evidence of infection was also available. Knowledge of the CFT reading at the initial and a subsequent blood test proved useful in distinguishing false-positive and true-positive brucellosis results. There was poor correlation between the CFT and iELISA results, and between the CFT and BST results. As a result of this study, national policy has been modified to include re-sampling of all animals with CFT readings of 20 IU or greater. This project has also led to a reduction in the number of herds restricted, as well as restriction duration. It has also contributed to a reduction in the number of herds listed for contiguous tests, and therefore the potential for contiguity testing of false positive results.
自 1998 年以来，由于牛布鲁氏菌病，爱尔兰的畜群限制和减畜数量稳步下降。由于爱尔兰布鲁氏菌病的流行率下降，人们担心实验室结果的解释可能会变得越来越成问题。因此，本研究的目的是评估爱尔兰畜群和具有牛布鲁氏菌病不确定血清学证据的动物的感染状况。在 2004 年 9 月 1 日至 12 个月期间，从所有爱尔兰畜群中收集了实验室和观察性流行病学数据，这些畜群中的动物检测发现至少有一只动物的补体固定试验（CFT）读数大于零和/或间接酶联免疫吸附试验（iELISA）呈阳性。由于研究的观察性质，我们对 CFT、iELISA 和布鲁氏菌素皮肤试验（BST）的相对性能（但不是绝对性能）有可靠的估计。根据初始评估时的测试结果，将畜群分为三类（A、B 或 C 组）。共有 639 个畜群参加了该研究，并在登记后至少观察了两年。一般来说，在随后的血液检测中 CFT 滴度升高，CFT 读数为 111 国际 CFT 单位（IU）或更高，与其他感染证据也可用的畜群相关。在初始和随后的血液检测中了解 CFT 读数有助于区分假阳性和真阳性布鲁氏菌病结果。CFT 与 iELISA 结果之间以及 CFT 与 BST 结果之间相关性较差。由于这项研究，国家政策已修改，包括对所有 CFT 读数为 20IU 或更高的动物进行重新采样。该项目还减少了受限制的畜群数量以及限制持续时间。它还减少了需要进行连续检测的畜群数量，从而降低了假阳性结果的连续检测的可能性。
