Gil Juliana, Pavía Paula, Montilla Marleny, Florez Astrid C, Quintero Claudia, Mercado Marcela, Vacca Miguel, Nicholls Santiago, Puerta Concepción
Laboratorio de Parasitología Molecular, Departamento de Microbiologia, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia.
Biomedica. 2007 Jan;27 Suppl 1:83-91.
Diagnosis of Chagas disease in its latent and chronic phase is difficult because of the low parasitemia levels. Therefore, serological and molecular techniques are necessary to achieve an appropriate diagnosis.
The polymerase chain reaction based on the amplification of the SIRE element inserted into H2A encoding genes was compared with classical serological tests for the diagnosis of Chagas disease in Colombian patients.
An agreement study was carried out by comparing the PCR with ELISA (enzyme linked immuno sorbent assay) and IFAT (indirect immunofluorescence) tests. In addition, the PCR sensitivity and specificity were determined. A sample of 156 individuals was tested with the H2A PCR primers after a Chagas disease classification based on clinical, epidemiological and serological data associated with each patient. In addition, 97 out of 156 samples were also compared with the S35/S36 PCR primers.
Eighty-nine of 156 samples (57%) were positive by both IFAT and ELISA and 84 (53.8%) presented the expected 234 bp amplification fragment. The sensitivity of the TcH2AF/ R PCR was 88% (95% C.I.: 75%--95%) and its specificity 92.5% (95% C.I.: 87.7%--97.2%). The kappa index for concordance between serological tests and TcH2AF/R PCR was 0.8 (95% C.I.: 73%--86%), and between the TcH2AF/R and S35/S36 PCR primers was 0.9 (95% C.I.: 84%-96%). These indices indicated a "good" and "almost perfect" agreement, respectively.
The TcH2AF/R PCR is a promising diagnostic tool for the detection of T. cruzi and is suggested as a tool complementary to the classical serological tests.
恰加斯病处于潜伏和慢性阶段时，由于寄生虫血症水平较低，诊断较为困难。因此，血清学和分子技术对于进行准确诊断是必要的。
将基于插入H2A编码基因的SIRE元件扩增的聚合酶链反应与用于诊断哥伦比亚患者恰加斯病的经典血清学检测进行比较。
通过将聚合酶链反应与酶联免疫吸附测定（ELISA）和间接免疫荧光法（IFAT）检测进行比较，开展了一项一致性研究。此外，还测定了聚合酶链反应的敏感性和特异性。根据与每位患者相关的临床、流行病学和血清学数据对恰加斯病进行分类后，用H2A聚合酶链反应引物对156名个体的样本进行检测。此外，还将156个样本中的97个与S35/S36聚合酶链反应引物进行了比较。
156个样本中有89个（57%）通过IFAT和ELISA检测均呈阳性，84个（53.8%）出现预期的234 bp扩增片段。TcH2AF/R聚合酶链反应的敏感性为88%（95%置信区间：75% - 95%），特异性为92.5%（95%置信区间：87.7% - 97.2%）。血清学检测与TcH2AF/R聚合酶链反应之间的一致性kappa指数为0.8（95%置信区间：73% - 86%），TcH2AF/R与S35/S36聚合酶链反应引物之间的kappa指数为0.9（95%置信区间：84% - 96%）。这些指数分别表明“良好”和“几乎完美”的一致性。
TcH2AF/R聚合酶链反应是检测克氏锥虫的一种有前景的诊断工具，建议作为经典血清学检测的补充工具。
