Laboratorio de Parasitología Básico-Clínico, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
PLoS One. 2019 Aug 21;14(8):e0221100. doi: 10.1371/journal.pone.0221100. eCollection 2019.
Chagas disease, a vector-borne parasitosis caused by Trypanosoma cruzi, is endemic to Latin America and has spread to other countries due to immigration of infected persons. It is estimated that 160,000 people are infected in Chile, most of them in the chronic phase and without etiological treatment. The infection is confirmed by conventional serological methods while molecular methods have become in valuable tools to evaluate parasitemia in treated and non-treated chronic Chagas disease patients. The objective of this study was to determine, by conventional Polymerase Chain Reaction, the presence of T. cruzi kinetoplastid DNA in peripheral blood samples from 114 adult individuals with confirmed chronic Chagas disease, before and 6.6 years (average) after treatment with nifurtimox. The samples were received and preserved in guanidine-EDTA until DNA purification. Conventional PCR assays were performed in triplicate with T. cruzi kinetoplastid DNA primers 121 and 122. The amplified products were fractionated by electrophoresis in 2% agarose gels. A 330 bp product represented a positive assay. 84.2% (96 cases) and 6.1% (7 cases) of the samples taken before and after the treatment, respectively, were positive. The McNemar test showed a statistically significant difference between the groups of samples (p<0.001). Since serological negativization (the current cure criterion) delay many years after therapy and positive parasitological results represent a treatment failure, the conversion of pre-therapy positive conventional PCR is a qualitative and complementary tool that could be included in protocols of prolonged follow-up.
恰加斯病是一种由克氏锥虫引起的虫媒寄生虫病，流行于拉丁美洲，由于受感染者的移民，已传播到其他国家。据估计，智利有 16 万人感染，其中大多数处于慢性期且未接受病因治疗。该感染通过常规血清学方法确认，而分子方法已成为评估治疗和未治疗的慢性恰加斯病患者寄生虫血症的有价值工具。本研究的目的是通过常规聚合酶链反应（PCR），确定 114 例经确诊患有慢性恰加斯病的成年个体在接受硝呋莫司治疗前后 6.6 年（平均）时外周血样本中是否存在克氏锥虫动基体 DNA。这些样本在收到并保存在胍-EDTA 中直至 DNA 纯化。使用克氏锥虫动基体 DNA 引物 121 和 122 进行了三次常规 PCR 检测。扩增产物在 2%琼脂糖凝胶中电泳分离。330 bp 的产物表示阳性检测。治疗前和治疗后分别有 84.2%（96 例）和 6.1%（7 例）的样本呈阳性。McNemar 检验显示两组样本之间存在统计学显著差异（p<0.001）。由于血清学转阴（当前的治愈标准）在治疗后多年才出现，并且阳性寄生虫学结果表示治疗失败，因此治疗前阳性常规 PCR 的转化是一种定性和补充工具，可以纳入延长随访的方案中。
