National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, 080-8555, Japan.
Unit for Environmental Sciences and Management, North-West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom, 2520, South Africa.
Ticks Tick Borne Dis. 2019 Jun;10(4):875-882. doi: 10.1016/j.ttbdis.2019.04.008. Epub 2019 Apr 15.
Ticks are involved in the transmission of many public health and veterinary important pathogens. Although tick-borne pathogens are widely distributed in South Africa, information on tick-pathogen relationship needs to be updated particularly using modern molecular techniques. This study used PCR and sequencing to confirm the identity of the tick species collected from cattle and sheep from KwaZulu-Natal, Free State and Eastern Cape. Furthermore, presence of Babesia spp., Theileria spp., Anaplasma marginale, Rickettsia spp., Ehrlichia ruminantium and Coxiella burnetii was detected from tick DNA using species-specific PCR or nested PCRs. The study samples consisted of 390 adult ticks (male and female) which were pooled according to species, host animal and sampling site (three ticks per pool) for DNA extraction. The PCR results revealed that out of 130 tick DNA pools, 30 (23.1%) were positive for at least one pathogen. The most frequent pathogen was C. burnetii (9.2%), followed by Rickettsia spp. (7.7%), A. marginale (3.8%), T. mutans (3.1%), T. taurotragi (2.3%) and E. ruminantium (1.5%). The highest prevalence of pathogens was observed in ticks collected from cattle in Eastern Cape (16/42) and the lowest was in ticks obtained from sheep in Free State (1/21). Infected ticks were identified as Rhipicephalus evertsi evertsi (n = 13), R. appendiculatus (n = 3), R. decoloratus (n = 7) and Amblyomma hebraeum (n = 7). Coinfection with two pathogens was found in 21% of pathogen-positive pools. Analysis of Theileria taurotragi 18S rRNA, T. mutans 18S rRNA, C. burnetii htpB, Rickettsia spp. gltA, Rickettsia spp. ompA, E. ruminantium pCS20 and A. marginale Msp5 sequences showed that the pathogens detected in this study were genetically related to isolates previously reported in Africa. These findings provide important information on distribution of ticks and tick-borne pathogens of ruminants and will contribute in the formulation of future control strategies in South Africa.
蜱虫在传播许多公共卫生和兽医重要病原体方面发挥着作用。尽管在南非广泛分布着蜱传病原体，但需要利用现代分子技术更新有关蜱虫-病原体关系的信息。本研究使用 PCR 和测序技术，从夸祖鲁-纳塔尔省、自由州和东开普省的牛和羊身上采集的蜱虫样本，确认其物种身份。此外，还使用种特异性 PCR 或巢式 PCR 从蜱虫 DNA 中检测到巴贝虫属、泰勒虫属、边缘无形体、立克次体属、埃立克体属和寇热螺旋体。本研究样本包括 390 只成年蜱虫（雌雄），根据物种、宿主动物和采样地点将其合并为 3 只蜱虫/组，用于 DNA 提取。PCR 结果显示，在 130 个蜱虫 DNA 池中，有 30 个（23.1%）至少有一种病原体呈阳性。最常见的病原体是寇热螺旋体（9.2%），其次是立克次体属（7.7%）、边缘无形体（3.8%）、突变泰勒虫（3.1%）、塔氏泰勒虫（2.3%）和埃立克体属（1.5%）。在东开普省采集的牛蜱虫中观察到的病原体患病率最高（16/42），在自由州采集的绵羊蜱虫中观察到的病原体患病率最低（1/21）。鉴定出感染的蜱虫为钝缘蜱（n=13）、扇头蜱（n=3）、无色革蜱（n=7）和荒地革蜱（n=7）。在 21%的病原体阳性池中发现了两种病原体的混合感染。对塔氏泰勒虫 18S rRNA、突变泰勒虫 18S rRNA、寇热螺旋体 htpB、立克次体属 gltA、立克次体属 ompA、埃立克体属 pCS20 和边缘无形体 Msp5 序列的分析表明，本研究中检测到的病原体与之前在非洲报道的分离株在遗传上具有相关性。这些发现为反刍动物的蜱虫和蜱传病原体的分布提供了重要信息，并将有助于制定南非未来的控制策略。
