OneHealth Group, Carrera de Medicina, Facultad de Ciencias de la Salud, Universidad De Las Américas (UDLA), Quito, Ecuador.
Department of Ecology and Evolutionary Biology - Biodiversity Institute, University of Kansas, Lawrence, Kansas, United States of America.
PLoS One. 2018 Oct 4;13(10):e0203811. doi: 10.1371/journal.pone.0203811. eCollection 2018.
Recently, a high prevalence of infection by the liver fluke Amphimerus spp. has been documented in the Chachi Amerindians of Ecuador. For diagnosis, no studies exist that compare the sensitivity of different coproparasitological detection techniques. The present study compares the Kato-Katz technique with three other coproparasitological methods for detecting eggs of Amphimerus in stools, as well as determines the prevalence of infection in Chachi residents in a Tropical rain forest area in the northwest coast of Ecuador.
METHODOLOGY/RESULTS: A total of 105 samples, utilizing the Kato-Katz technique (KK), the spontaneous sedimentation technique in tube (SSTT), the formalin-ether concentration technique (FEC), and direct smear microscopy (DM), were examined. Combining the four methods (fixed "gold" standard), 38 samples were positive with a prevalence of infection of 36.2%. The sensitivities of individual methods were 71%, 58%, 50% and 3% for KK, SSTT, FEC, and DM respectively. Our results indicated that KK alone had the best performance, detecting 27 (71%) of the 38 positive samples. The combination of KK and SSTT detected amphimeriasis in 36 (95%) samples, and KK and FEC in 31 (82%) samples.
DM showed the lowest sensitivity, which raises concern for its value, because it is the standard technique for stool examination for detection of parasites in both public and private laboratories in Ecuador. SSTT alone detected eggs in 22 samples (58%) and would be recommended for field studies because of its simplicity. Performing two techniques on a single sample enhances the detection of Amphimerus infection. Its sensitivity is relative to a fixed "gold" standard, determined as the combined results of the four techniques performed. This study confirms the high prevalence of human infection by Amphimerus in the indigenous Chachi group where the first human cases were described.
最近，在厄瓜多尔的查奇印第安人中发现了肝吸虫 Amphimerus spp. 的高感染率。对于诊断，尚无研究比较不同粪便寄生虫学检测技术的敏感性。本研究比较了加藤厚涂片法（Kato-Katz technique）与另外三种粪便寄生虫学方法检测粪便中 Amphimerus 虫卵的效果，并确定了在厄瓜多尔西北海岸热带雨林地区的查奇居民中的感染率。
方法/结果：共检查了 105 个样本，使用加藤厚涂片法（Kato-Katz technique，KK）、管内自然沉淀法（spontaneous sedimentation technique in tube，SSTT）、福尔马林-乙醚沉淀法（formalin-ether concentration technique，FEC）和直接涂片镜检法（direct smear microscopy，DM）。结合这四种方法（固定的“金标准”），38 个样本呈阳性，感染率为 36.2%。各方法的敏感性分别为 71%、58%、50%和 3%，用于 KK、SSTT、FEC 和 DM。结果表明，单独使用 KK 的性能最佳，可检测到 38 个阳性样本中的 27 个（71%）。KK 和 SSTT 联合检测到 36 个（95%）样本中的 Amphimeriasis，KK 和 FEC 联合检测到 31 个（82%）样本中的 Amphimeriasis。
DM 的敏感性最低，这令人对其在厄瓜多尔的公共和私人实验室中检测寄生虫的标准技术的价值产生了担忧。SSTT 单独检测到 22 个样本（58%）中的虫卵，因其简单而推荐用于现场研究。在单个样本上执行两种技术可以提高检测 Amphimerus 感染的灵敏度。其灵敏度与固定的“金标准”相关，该标准为四种技术联合检测的结果。本研究证实了在查奇土著人群中，人类感染 Amphimerus 的高流行率，这是首次在人类病例中描述的。
