Departamento de Microbiologia e Imunologia, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, SP, Brasil, 18618-000.
Mem Inst Oswaldo Cruz. 2010 Feb;105(1):57-61. doi: 10.1590/s0074-02762010000100008.
More sensitive methodologies are necessary to improve strongyloidiasis diagnosis. This study compared the sensitivities of the McMaster modified technique and polymerase chain reaction (PCR) assays, both performed in faecal samples. Lewis rats were subcutaneously infected with 4,000, 400 or 40 infective third-stage larvae, considered as high, moderate or low infection, respectively. Seven days later, they were euthanized to count adult nematodes recovered from the small intestine. Stool samples were used to count the number of eggs per gram (EPG) of faeces and to detect parasite DNA by PCR performed with a species and a genus primer pair. The sensitivity of these assays depended upon parasite burden and the primer specificity. All assays presented 100% sensitivity at the highest parasite load. In the moderate infection, EPG and PCR with the genus primer maintained 100% specificity, whereas PCR sensitivity with the species primer decreased to 77.7%. In low infection, the sensitivity was 60% for EPG, 0% for PCR with the species primer and 90% for PCR done with the genus primer. Together, these results suggest that PCR with a genus primer can be a very sensitive methodology to detect Strongyloides venezuelensisin faeces of Lewis rats infected with very low parasite burden.
需要更敏感的方法来提高粪类圆线虫病的诊断水平。本研究比较了 McMaster 改良技术和聚合酶链反应（PCR）检测在粪便样本中的敏感性。将 4000、400 或 40 条感染性第三期幼虫分别皮下感染到路易斯大鼠，分别认为是高、中、低感染。7 天后，处死大鼠，计算从小肠中回收的成年线虫数量。使用粪便样本计算粪便每克虫卵数（EPG），并使用种和属引物对通过 PCR 检测寄生虫 DNA。这些检测的敏感性取决于寄生虫负担和引物特异性。在最高寄生虫负荷时，所有检测方法的敏感性均为 100%。在中度感染中，EPG 和使用属引物的 PCR 保持 100%的特异性，而使用种引物的 PCR 敏感性下降至 77.7%。在低感染中，EPG 的敏感性为 60%，种引物的 PCR 敏感性为 0%，属引物的 PCR 敏感性为 90%。综上所述，使用属引物的 PCR 可以是一种非常敏感的方法，可用于检测感染非常低寄生虫负担的路易斯大鼠粪便中的委内瑞拉类圆线虫。
