Department of Veterinary Microbiology, College of Veterinary and Animal Sciences, Mannuthy, Thrissur, Kerala, India- 680 651.
Dept. of Veterinary Microbiology, College of Veterinary Science, Mamnoor Warangal Dist., India.
Trop Biomed. 2019 Sep 1;36(3):654-663.
A study was undertaken to evaluate the relevance of detecting IgM and IgG antibodies in diagnosis of canine leptospirosis in Kerala, a southern state of India, which is endemic for the disease. A total of 205 blood (35 from healthy vaccinated, 30 from healthy unvaccinated and 140 from diseased dogs) and 151 urine samples (11 from healthy vaccinated and 140 from diseased dogs) were collected from three districts of Kerala, Thrissur, Palakkad and Kozhikode with high incidence of leptospirosis. Recombinant LipL41 protein was used as antigen and IgG and IgM based ELISAs were standardized. The results were compared with the gold standard test, microscopic agglutination test (MAT). The MAT positive samples (146 samples) were divided into those having titre >1:800 and those between 1:100 and 1:400 in view that the former constituted the acute cases. It was found that IgM ELISA was more specific and sensitive in detecting acute cases (MAT >1:800) whereas IgG ELISA was less specific. In case of seroprevalence studies (MAT titre 1:100 to 1: 400), IgG ELISA was found to be more sensitive and specific than IgM ELISA. Receiver operating characteristic curves when plotted, revealed the accuracy of IgM ELISA in acute leptospirosis. Many samples were positive for both IgG and IgM antibodies. Polymerase Chain Reaction (PCR) targeting lipl41 gene was standardized and urine and blood samples from the same dogs were tested. PCR was found to be the specific test for the early detection of leptospires in blood even before seroconversion. However, PCR analysis of the urine samples was found to be insensitive. Hence, it can be concluded that the diagnostic strategies should be modified, and a combination of serological and molecular tests is recommended in endemic areas rather than simple detection of IgM or IgG antibodies, for the early detection of acute clinical cases of leptospirosis.
一项研究旨在评估在印度南部的喀拉拉邦（该邦是该疾病的流行地区）检测犬钩端螺旋体病的 IgM 和 IgG 抗体的相关性。总共从三个地区收集了 205 份血液（35 份来自健康接种疫苗的狗，30 份来自健康未接种疫苗的狗和 140 份来自患病狗）和 151 份尿液样本（11 份来自健康接种疫苗的狗和 140 份来自患病狗）。这些样本来自喀拉拉邦的三个地区，分别是 Thrissur、Palakkad 和 Kozhikode，这些地区的钩端螺旋体病发病率很高。使用重组 LipL41 蛋白作为抗原，对 IgG 和 IgM 基于 ELISA 进行了标准化。将结果与金标准检测（微量凝集试验，MAT）进行比较。MAT 阳性样本（146 个样本）分为滴度>1：800 的样本和 1：100 到 1：400 之间的样本，因为前者构成了急性病例。结果发现，IgM ELISA 在检测急性病例（MAT>1：800）时更具特异性和敏感性，而 IgG ELISA 的特异性较低。在血清流行率研究（MAT 滴度为 1：100 至 1：400）中，发现 IgG ELISA 比 IgM ELISA 更敏感和特异。绘制的受试者工作特征曲线显示，IgM ELISA 在急性钩端螺旋体病中的准确性。许多样本同时检测出 IgG 和 IgM 抗体阳性。针对 lipl41 基因的聚合酶链反应（PCR）也进行了标准化，并对来自同一狗的尿液和血液样本进行了测试。PCR 被发现是血液中钩端螺旋体早期检测的特异性试验，甚至在血清转换之前。然而，尿液样本的 PCR 分析发现不敏感。因此，可以得出结论，在流行地区，诊断策略应该进行修改，建议采用血清学和分子检测相结合的方法，而不是简单地检测 IgM 或 IgG 抗体，以早期检测钩端螺旋体病的急性临床病例。
