Mossaad Ehab, Salim Bashir, Suganuma Keisuke, Musinguzi Peter, Hassan Mohammed A, Elamin E A, Mohammed G E, Bakhiet Amel O, Xuan Xuenan, Satti Rawan A, Inoue Noboru
Department of Pathology, Parasitology and Microbiology, College of Veterinary Medicine, Sudan University of Science and Technology, P.O. Box 204, Khartoum, Sudan.
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, 080-8555, Japan.
Parasit Vectors. 2017 Apr 13;10(1):176. doi: 10.1186/s13071-017-2117-5.
This study was conducted in response to recurring reports from eastern Sudan of camel trypanosomosis that can no longer be treated by currently available trypanocidal drugs. One hundred and eighty-nine blood samples were obtained from camels in different herds and local markets in the western part of Sudan, and a cross-sectional study was carried out between December 2015 and February 2016 to identify the causative agents and possible circulating genotypes.
The prevalence of trypanosomes detected using the conventional parasitological techniques of Giemsa-stained blood smears, wet blood smears and the microhematocrit centrifugation technique (MHCT) was 7% (13/189), 11% (21/189) and 19% (36/189), respectively. However, a multi-species KIN-PCR targeting the ITS region revealed that the prevalence of Trypanosoma evansi was 37% (70/189), while that of T. vivax was 25% (47/189). Consequently, we used a T. evansi-specific PCR (RoTat1.2 VSG gene) to analyse the KIN-PCR-positive samples and a T. vivax-specific PCR (Cathepsin L-like gene) to analyse all of the samples. The prevalence of T. evansi was 59% (41/70), while the prevalence of T. vivax was 31% (59/189). Mixed infections were detected in 18% (34/189) of the samples. These results were further confirmed by sequencing and a phylogenetic analysis of the complete internal transcribed spacer (ITS) region of T. evansi and the TviCatL gene of T. vivax.
We conclude that T. vivax was newly introduced to the camel population and that T. evansi is no longer the single cause of camel trypanosomosis in Sudan. The presence of T. vivax in camels detected in this study is a challenge in the choice of diagnostic approaches, particularly serology, and PCRs. However, an analysis of drug resistance should be performed, and the genotypic variation should be verified. To our knowledge, this is the first molecular study on T. vivax and mixed-infection with T. vivax and T. evansi in Sudanese camels.
本研究是针对苏丹东部不断传来的骆驼锥虫病报告而开展的，目前可用的杀锥虫药物已无法治疗这种疾病。从苏丹西部不同畜群和当地市场的骆驼身上采集了189份血样，并于2015年12月至2016年2月开展了一项横断面研究，以确定病原体和可能传播的基因型。
使用吉姆萨染色血涂片、湿血涂片和微量血细胞比容离心技术（MHCT）等传统寄生虫学技术检测到的锥虫患病率分别为7%（13/189）、11%（21/189）和19%（36/189）。然而，针对ITS区域的多物种KIN-PCR显示，伊氏锥虫的患病率为37%（70/189），而间日锥虫的患病率为25%（47/189）。因此，我们使用伊氏锥虫特异性PCR（RoTat1.2 VSG基因）分析KIN-PCR阳性样本，并使用间日锥虫特异性PCR（组织蛋白酶L样基因）分析所有样本。伊氏锥虫的患病率为59%（41/70），而间日锥虫的患病率为31%（59/189）。在18%（34/189）的样本中检测到混合感染。通过对伊氏锥虫完整内部转录间隔区（ITS）区域和间日锥虫TviCatL基因进行测序和系统发育分析，进一步证实了这些结果。
我们得出结论，间日锥虫是新传入骆驼群体的，并且伊氏锥虫不再是苏丹骆驼锥虫病的唯一病因。本研究中在骆驼身上检测到间日锥虫，这对诊断方法的选择，尤其是血清学和PCR检测，构成了挑战。然而，应进行耐药性分析，并验证基因型变异。据我们所知，这是苏丹骆驼中间日锥虫以及间日锥虫与伊氏锥虫混合感染的首次分子研究。
