Angkwanish Taweepoke, Vernooij Hans J C M, Sirimalaisuwan Anucha, Charernpan Pattara, Nielen Mirjam, Rutten Victor P M G
Department Biomolecular Health Sciences, Division Infectious Diseases and Immunology, Section Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands.
National Elephant Institute, Forest Industry Organization, Lampang, Thailand.
Front Vet Sci. 2021 Nov 2;8:713663. doi: 10.3389/fvets.2021.713663. eCollection 2021.
To address putative TB statuses of elephants and to identify and quantify potential demographic risk factors for TB, three ELISAs specific for different mycobacterial antigens (ESAT6, CFP10, MPB83) and the TB Stat-Pak assay were used as surrogate serological markers for TB infection in elephants. In view of the low number of animals of which the infected status could be confirmed (4 out of 708) Latent Class Analyses of TB serology test outcomes was used to predict the putative TB status of each of 708 elephants as positive (17.3%), inconclusive (48.7%), or negative (34%) when assessed on a population basis. Correlation between test performance of the individual assays was high between the ELISAs, but low with that of the TB Stat-Pak assay. Risk factors, assessed based on cut off values for each of the ELISAs determined by ROC analysis, included sex, BCS, age, working time, feed type, management system, camp size and region. Old age elephants were more likely to show a positive TB serology test outcome, than younger ones. Elephants working 7 h per day and the ones in good condition BCS (7-11) were less likely to be positive in TB serology testing. In addition, fewer animals in the large camp size (31-50 elephants) were found to be positive in ELISA tests, compared to elephants in the other camp sizes. In this study, the North region had the lowest percentages of elephants with positive TB test outcome, the West region and to a lesser extend the other regions showed clearly higher percentages of positive animals. Even though assays used in the present study have not been validated yet, results obtained showed promise as diagnostic or screening tests. For the diagnosis of animals suspected to be infected, the ELISA tests, once further optimized for the individual antigens, can be used in parallel. For screening of complete camps for presence or absence of infection, a single optimized ELISA test can be utilized.
为了确定大象假定的结核病状况，并识别和量化结核病潜在的人口统计学风险因素，使用了三种针对不同分枝杆菌抗原（ESAT6、CFP10、MPB83）的酶联免疫吸附测定（ELISA）以及结核病快速检测试剂盒作为大象结核病感染的替代血清学标志物。鉴于能够确认感染状况的动物数量较少（708头中有4头），在对总体进行评估时，采用结核病血清学检测结果的潜在类别分析来预测708头大象中每头大象假定的结核病状况为阳性（17.3%）、不确定（48.7%）或阴性（34%）。各ELISA检测之间的个体检测性能相关性较高，但与结核病快速检测试剂盒的相关性较低。根据ROC分析确定的每种ELISA的临界值评估的风险因素包括性别、体况评分、年龄、工作时间、饲料类型、管理系统、营地规模和地区。老年大象比年轻大象更有可能呈现结核病血清学检测阳性结果。每天工作7小时的大象以及体况良好（体况评分7 - 11）的大象在结核病血清学检测中呈阳性的可能性较小。此外，与其他营地规模的大象相比，大型营地规模（31 - 50头大象）中ELISA检测呈阳性的动物较少。在本研究中，北部地区结核病检测呈阳性的大象百分比最低，西部地区以及在较小程度上其他地区显示阳性动物的百分比明显更高。尽管本研究中使用的检测方法尚未经过验证，但获得的结果有望作为诊断或筛查检测方法。对于疑似感染动物的诊断，一旦针对各个抗原进一步优化，ELISA检测可并行使用。对于筛查整个营地是否存在感染，可使用单一优化的ELISA检测。
