Kamani Joshua, Baneth Gad, Harrus Shimon
Parasitology Division, National Veterinary Research Institute (NVRI), PMB 01 Vom, Plateau State, Nigeria.
Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel.
Vet Parasitol Reg Stud Reports. 2019 Jan;15:100255. doi: 10.1016/j.vprsr.2018.12.001. Epub 2018 Dec 3.
Tick-borne pathogens are transmitted by the bite of a tick vector or the ingestion therein by a susceptible host. Conventionally, the diagnosis of tick-borne parasites in Nigeria is achieved through the demonstration of their developmental stages in the host's blood or tissues. These classical methods are limited in their capability to detect chronic cases or healthy carriers and to differentiate between pathogens of similar morphological features. Molecular diagnostic techniques of high sensitivity have been developed to overcome these shortfalls by detecting the pathogen's DNA, elucidating their genetic makeup and comparing their phylogenetic relationship to other pathogens, sometimes necessitating taxonomic changes. Detection of DNA of canine tick-borne pathogens (CTBPs) such as Ehrlichia canis, Hepatozoon canis, and Mycoplasma haemocanis has been reported in Nigerian dogs corroborating earlier microscopic findings. Furthermore, DNA of Anaplasma platys, Ehrlichia ewingii, 'Candidatus Mycoplasma haemobos' and Theileria sp. hitherto considered to be absent in Nigeria has been detected, thereby expanding the spectrum of CTBPs in the country. However, in some cases, diagnoses based on the detection of single short DNA fragments from pathogens can cause considerable confusion. This occurred in the case of the large canine Babesia, previously referred to as Babesia canis which has been reported in Nigerian dogs. There appears to be confusion regarding the accurate status of this pathogen in Nigeria due to the subsequent classification into Babesia canis, Babesia vogeli and Babesia rossi. Moreover, several molecular studies failed to detect the DNA of Babesia gibsoni previously reported in Nigerian dogs by light microscope. These findings necessitate regular update of the list of CTBPs of veterinary and medical importance, in order to keep practitioners abreast with these changes. Herein, an annotated checklist of tick-borne pathogens of dogs in Nigeria, based on available data from both classical and molecular studies, with notes explaining any discrepancies between the methods and probable explanations thereof, is presented.
蜱传病原体通过蜱虫媒介的叮咬或易感宿主的摄入而传播。传统上，尼日利亚蜱传寄生虫的诊断是通过在宿主血液或组织中显示其发育阶段来实现的。这些经典方法在检测慢性病例或健康携带者以及区分形态特征相似的病原体方面能力有限。已经开发出高灵敏度的分子诊断技术来克服这些不足，通过检测病原体的DNA，阐明其基因组成，并比较它们与其他病原体的系统发育关系，有时这需要进行分类学上的改变。在尼日利亚的犬类中已报告检测到犬埃立克体、犬肝簇虫和犬支原体等犬蜱传病原体（CTBP）的DNA，这证实了早期的显微镜检查结果。此外，还检测到了此前认为在尼日利亚不存在的扁平无形体、尤因埃立克体、“嗜血型假支原体”和泰勒虫属的DNA，从而扩大了该国CTBP的种类范围。然而，在某些情况下，基于检测病原体单个短DNA片段的诊断可能会造成相当大的混淆。尼日利亚犬类中曾报道过一种大型犬巴贝斯虫，之前称为犬巴贝斯虫，就出现了这种情况。由于随后该病原体被分类为犬巴贝斯虫、沃氏巴贝斯虫和罗氏巴贝斯虫，其在尼日利亚的确切分类似乎存在混淆。此外，几项分子研究未能检测到此前通过光学显微镜在尼日利亚犬类中报告的吉氏巴贝斯虫的DNA。这些发现有必要定期更新具有兽医和医学重要性的CTBP清单，以便从业者了解这些变化。在此，根据经典研究和分子研究的现有数据，列出了一份尼日利亚犬类蜱传病原体的注释清单，并对方法之间的任何差异及其可能的解释进行了说明。
