Abstract：
OBJECTIVE: Babesiosis is one of the most important globally extended and quickly spreading tick-borne infections of dogs. Diagnosis of babesiosis in Sri Lanka is based on clinical signs followed by thin blood smears which could be error-prone due to undetected early infections, absence of clinical signs or low parasitemia. The present study investigated the prevalence of babesiosis in dogs presented to the Veterinary Teaching Hospital (VTH) at the Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, for treatments, vaccinations, and regular check-ups, and compared the diagnosis methods of microscopy and molecular analysis.
METHODS: Blood samples from dogs were collected from January to June 2019. First, Giemsa stained blood smears were prepared, and then the blood samples were subjected to PCR using genus-specific primers to amplify a 411-450 bp region in the 18S rRNA gene. Twenty samples from PCR amplified products were sequenced for species identification and phylogenetic analysis. Clinical signs of the dogs were noted down, and ticks were also collected from dogs if any.
RESULTS: Results show a very high prevalence of canine babesiosis (78.6%) among the dogs brought to the VTH. The parasite was identified microscopically and genetically as Babesia gibsoni. A large percentage (66.7%) of infections was asymptomatic. Out of 42 blood samples, 19 (45.2%) were microscopically positive for babesiosis while 33 (78.6%) were PCR positive, showing a significant difference in the two methods of diagnosis (chi-square test, χ2 = 9.462, p = 0.002). Three tick species: Rhipicephalus haemaphysaloides, Haemaphysalis bispinosa, and Rhipicephalus sanguineus were found attached to the dogs.
CONCLUSIONS: This study shows a very high prevalence of canine babesiosis among dogs in the Kandy area. Most of these infections might go undetected if only microscopy was used to diagnose. An improved, rapid diagnostic method such as the novel, PCR-based point-of-care diagnostic method that detects very low parasitemia within 30 min is needed. Moreover, as most infected dogs did not show clinical signs, they may act as reservoirs of infection. The ability of asymptomatic dogs to spread babesiosis should be investigated.
METHODS: Blood samples from dogs were collected from January to June 2019. First, Giemsa stained blood smears were prepared, and then the blood samples were subjected to PCR using genus-specific primers to amplify a 411-450 bp region in the 18S rRNA gene. Twenty samples from PCR amplified products were sequenced for species identification and phylogenetic analysis. Clinical signs of the dogs were noted down, and ticks were also collected from dogs if any.
RESULTS: Results show a very high prevalence of canine babesiosis (78.6%) among the dogs brought to the VTH. The parasite was identified microscopically and genetically as Babesia gibsoni. A large percentage (66.7%) of infections was asymptomatic. Out of 42 blood samples, 19 (45.2%) were microscopically positive for babesiosis while 33 (78.6%) were PCR positive, showing a significant difference in the two methods of diagnosis (chi-square test, χ2 = 9.462, p = 0.002). Three tick species: Rhipicephalus haemaphysaloides, Haemaphysalis bispinosa, and Rhipicephalus sanguineus were found attached to the dogs.
CONCLUSIONS: This study shows a very high prevalence of canine babesiosis among dogs in the Kandy area. Most of these infections might go undetected if only microscopy was used to diagnose. An improved, rapid diagnostic method such as the novel, PCR-based point-of-care diagnostic method that detects very low parasitemia within 30 min is needed. Moreover, as most infected dogs did not show clinical signs, they may act as reservoirs of infection. The ability of asymptomatic dogs to spread babesiosis should be investigated.
摘要：
目的：Babesiosis是一种最重要的全球扩展和迅速传播的狗传播感染。在斯里兰卡，巴贝西虫病的诊断是基于临床症状，然后是薄的血液涂片，由于未检测到早期感染，因此容易出错。没有临床症状或低寄生虫血症。本研究调查了兽医和动物科学学院兽医教学医院（VTH）的狗的巴贝斯病患病率，Peradeniya大学,为了治疗，疫苗接种,定期检查,并比较了显微镜和分子分析的诊断方法。
方法：从2019年1月至6月收集狗的血液样本。首先,准备了Giemsa染色的血涂片，然后使用属特异性引物对血液样品进行PCR，以扩增18SrRNA基因中的411-450bp区域。对来自PCR扩增产物的20个样品进行了测序，以进行物种鉴定和系统发育分析。记录了狗的临床症状，如果有的话，也从狗身上收集蜱。
结果：结果显示，在被带到VTH的狗中，犬巴贝斯虫病的患病率很高（78.6％）。该寄生虫在显微镜和基因上被鉴定为gibsoni巴贝斯虫。很大比例（66.7％）的感染是无症状的。在42份血液样本中，19例(45.2%)为巴贝斯虫病镜检阳性，33例(78.6%)为PCR阳性，显示两种诊断方法的显著差异(卡方检验，χ2=9.462,p=0.002)。三种tick虫：Hypicephalushemphysaloides，双皮松血盐，和血根虫被发现附着在狗身上。
结论：这项研究表明，在康提地区的狗中，犬巴贝斯虫病的患病率很高。如果仅使用显微镜诊断，大多数这些感染可能不会被发现。一个改进的,快速诊断方法，如新颖的，需要基于PCR的即时诊断方法，可在30分钟内检测到非常低的寄生虫血症。此外，因为大多数被感染的狗没有临床症状，它们可能是感染的宿主。应研究无症状犬传播巴贝斯虫病的能力。
方法：从2019年1月至6月收集狗的血液样本。首先,准备了Giemsa染色的血涂片，然后使用属特异性引物对血液样品进行PCR，以扩增18SrRNA基因中的411-450bp区域。对来自PCR扩增产物的20个样品进行了测序，以进行物种鉴定和系统发育分析。记录了狗的临床症状，如果有的话，也从狗身上收集蜱。
结果：结果显示，在被带到VTH的狗中，犬巴贝斯虫病的患病率很高（78.6％）。该寄生虫在显微镜和基因上被鉴定为gibsoni巴贝斯虫。很大比例（66.7％）的感染是无症状的。在42份血液样本中，19例(45.2%)为巴贝斯虫病镜检阳性，33例(78.6%)为PCR阳性，显示两种诊断方法的显著差异(卡方检验，χ2=9.462,p=0.002)。三种tick虫：Hypicephalushemphysaloides，双皮松血盐，和血根虫被发现附着在狗身上。
结论：这项研究表明，在康提地区的狗中，犬巴贝斯虫病的患病率很高。如果仅使用显微镜诊断，大多数这些感染可能不会被发现。一个改进的,快速诊断方法，如新颖的，需要基于PCR的即时诊断方法，可在30分钟内检测到非常低的寄生虫血症。此外，因为大多数被感染的狗没有临床症状，它们可能是感染的宿主。应研究无症状犬传播巴贝斯虫病的能力。
