Influence of age and purpose for testing on the cut-off selection of serological methods in bovine neosporosis
Influence of age and purpose for testing on the cut-off selection of serological methods in bovine neosporosis
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DOI：
10.1051/vetres:2003009
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发表时间：
2003-05-01
影响因子：
4.4
通讯作者：
Ortega-Mora, LM
中科院分区：
文献类型：
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作者：
Alvarez-García, G;Collantes-Fernández, E;Ortega-Mora, LM
这项研究的目的是根据动物年龄和检测目的，调查在牛新孢子虫病中最广泛使用的两种血清学技术IFAT和粗抗原ELISA(Civtest(R)，HIPRA)是否需要不同的界点。因此，使用的人群参考血清是使用多种标准的组合来定义的，例如流行病学/临床和组织病理学参数以及免疫印迹试验。首先，将胎儿和种牛(小母牛和母牛)作为单独的亚群进行血清学评估。其次，根据受试者工作特征(ROC)分析，根据年龄组(胎儿和种牛)和不同的实际应用(检测感染和流产)计算每种血清学技术(IFAT和ELISAT)的临界点。对于流产的种牛，定义了IFAT和ELISAT的分界点，在胎儿的情况下，假设假阳性和阴性结果的成本相等，单独使用IFAT。在感染的种牛、IFAT和ELISA法以及用于ELISA法的胎儿中，获得了两个可能的临界值，一个是最高灵敏度，另一个是最大特异度，并定义了结果不明确的间隔。在这种情况下，同样的灵敏度和特异度的分界值也被估计。当感染种牛的分界点为1：100~1：250时，IFAT的分界点为1：100~1：250，ELISAT的分界点为0.306~0.451，观察到最佳的和相似的阴性和阳性预测值，以及相似的表观和真实流行结果，表明两种检测方法交替使用的可能性。
The aim of this study was to investigate the need for different cut-off points, according to animal age and the purpose of testing, for two of the most widely used serological techniques in bovine neosporosis, IFAT and a crude antigen ELISA (Civtest(R), HIPRA). Therefore, the population reference sera used were defined using a combination of multiple criteria such as epidemiological/clinical and histopathological parameters and an immunoblot test. Firstly, foetuses and breeding cattle (heifers and cows) were considered as separate subpopulations for serological evaluation. Secondly, cut-off points for each serological technique (IFAT and ELISA) according to age group (foetuses and breeding cattle) and the different practical applications (detection of infection and abortion) were calculated following the receiver operating characteristics (ROC) analysis. Cut-off points were defined, for IFAT and ELISA for aborted breeding cattle and for IFAT alone in the case of the foetuses, assuming an equivalent cost of false positive and negative results. In infected breeding cattle, for IFAT and ELISA and in foetuses for ELISA, two possible cut-off values were obtained, one for a maximum sensitivity and one for a maximum specificity and the intervals of unclear results were defined. In this case, a cut-off value for equal sensitivity and specificity was also estimated. When cut-off points for infected breeding cattle, 1:100-1:250 for IFAT and 0.306-0.451 for ELISA were applied to a target population, optimal and similar negative and positive predictive values together with similar apparent and true prevalence results were observed suggesting the possibility of using both tests interchangeably.