在尼日利亚自然感染的狗中鉴定布氏冈比亚锥虫。
Identification of Trypanosoma brucei gambiense in naturally infected dogs in Nigeria.
机构信息
Department of Veterinary Medicine, Faculty of Veterinary Medicine, University of Abuja, Abuja, Nigeria.
Department of Veterinary Medicine, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Nigeria.
出版信息
Parasit Vectors. 2019 Aug 27;12(1):420. doi: 10.1186/s13071-019-3680-8.
BACKGROUND
Animal trypanosomosis is endemic in Nigeria, while the human disease caused by Trypanosoma brucei gambiense is rarely reported nowadays after efforts to bring it under control in the 20th century. The University of Nigeria Veterinary Teaching Hospital (UNVTH) is a reference centre located within the Nsukka area and serves Enugu and neighboring states, Benue, Kogi, Anambra and Delta. Among dogs presented to the UNVTH with canine trypanosomosis, T. brucei is frequently reported as the causative agent. However, this is by morphological identification under the microscope, which does not allow distinction of human-infective (T. b. gambiense) and non-human-infective (T. b. brucei) subspecies. Here, we used subspecies-specific PCR tests to distinguish T. b. gambiense and T. b. brucei.
METHODS
Blood samples were collected on FTA cards from 19 dogs presenting with clinical signs of trypanosomosis at the UNVTH from January 2017 to December 2018. All dogs had a patent parasitaemia. DNA was extracted from the FTA cards using Chelex 100 resin and used as template for PCR.
RESULTS
All infections were initially identified as belonging to subgenus Trypanozoon using a generic PCR test based on the internal transcribed spacer 1 (ITS1) of the ribosomal RNA locus and a PCR test specific for the 177 bp satellite DNA of subgenus Trypanozoon. None of the samples were positive using a specific PCR test for T. evansi Type A kinetoplast DNA minicircles. Further PCR tests specific for T. b. gambiense based on the TgsGP and AnTat 11.17 genes revealed that two of the dogs harboured T. b. gambiense. In addition to trypanosomes of subgenus Trypanozoon, T. congolense savannah was identified in one dog using a species-specific PCR test for this taxon.
CONCLUSIONS
Nineteen dogs presenting with canine African trypanosomosis at UNVTH were infected with trypanosomes of the T. brucei group and in two cases the trypanosomes were further identified to subspecies T. b. gambiense using specific PCR tests. Thus T. b. gambiense is one of the parasites responsible for canine African trypanosomosis in the Nsukka area of Nigeria and represents a serious danger to human health.
背景
动物锥虫病在尼日利亚流行，而 20 世纪以来，通过努力控制布氏冈比亚锥虫引起的人类疾病已很少见。尼日利亚大学兽医教学医院（UNVTH）是位于恩苏卡地区的一个参考中心，为埃努古州和邻近的贝努埃州、科基州、阿南布拉州和三角洲州提供服务。在因犬类锥虫病而到 UNVTH 就诊的犬中，通常报告的病原体是布氏锥虫。然而，这是通过显微镜下的形态学鉴定得出的，无法区分人类感染（布氏冈比亚锥虫）和非人类感染（布氏布鲁斯锥虫）亚种。在这里，我们使用亚种特异性 PCR 测试来区分布氏冈比亚锥虫和布氏布鲁斯锥虫。
方法
2017 年 1 月至 2018 年 12 月，从 UNVTH 出现锥虫病临床症状的 19 只犬中采集 FTA 卡血液样本。所有犬均有明显的寄生虫血症。使用 Chelex 100 树脂从 FTA 卡中提取 DNA，并将其用作 PCR 模板。
结果
所有感染最初都被鉴定为属于内转录间隔区 1（ITS1）核糖体 RNA 基因座的通用 PCR 测试确定的原生动物亚属，以及针对原生动物亚属 177 bp 卫星 DNA 的 PCR 测试。没有一个样本对特定位点的 PCR 测试呈阳性，该特定位点用于检测埃氏锥虫 A 动基体 DNA 微环。进一步的基于 TgsGP 和 AnTat 11.17 基因的布氏冈比亚锥虫特异性 PCR 测试显示，其中 2 只犬携带布氏冈比亚锥虫。除了原生动物亚属的锥虫外，还通过针对该分类单元的物种特异性 PCR 测试在 1 只犬中鉴定出了热带草原锥虫。
结论
在 UNVTH 就诊的 19 只犬因犬类非洲锥虫病而感染布氏布鲁斯锥虫组的锥虫，在两种情况下，通过特定的 PCR 测试进一步将这些锥虫鉴定为亚种布氏冈比亚锥虫。因此，布氏冈比亚锥虫是尼日利亚恩苏卡地区引起犬类非洲锥虫病的寄生虫之一，对人类健康构成严重威胁。
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