Helmy Yosra A, Klotz Christian, Wilking Hendrik, Krücken Jürgen, Nöckler Karsten, Von Samson-Himmelstjerna Georg, Zessin Karl-H, Aebischer Toni
Department of Animal Hygiene, Zoonoses and Animal Ethology, Faculty of Veterinary Medicine, Suez Canal University, 41511 Ismailia, Egypt.
Parasit Vectors. 2014 Jul 11;7:321. doi: 10.1186/1756-3305-7-321.
Giardia duodenalis is a common flagellated protozoan parasite that infects the small intestine of a wide range of vertebrate hosts. This study aimed to determine whether tracing of G. duodenalis isolates by current genetic typing tools is possible using an exemplary set of samples from infected cattle, buffalo and children from the Ismailia province, Egypt.
A total of 804 fecal samples from ruminant animals was collected from 191 herds and 165 samples from diarrheal children below the age of 10 years. Parasites were detected in these samples using the copro-antigen RIDA®QUICK test and by real-time PCR. Samples were then genetically characterized based on the triosephosphate isomerase, glutamate dehydrogenase and β-giardin genes.
The prevalence of G. duodenalis was 53% in ruminants and 21% in symptomatic children and infection was not positively correlated with diarrheal symptoms. Sequence typing analysis confirmed predominance of B-type sequences (>67%) in humans and E-type sequences (>81%) in ruminants over A-type sequences. For 39 samples the complete sequence information of the three marker gene fragments could be derived. Integration of the concatenated sequence information of the three marker gene fragments with the spatial data of the respective sample revealed that identical or near identical (only up to 1 out of 1358 bp different) concatenated sequencing types were spatially related in 4 out of 5 cases.
The risk of zoonotic infection emanating from ruminants even in high prevalence areas is negligible. Genetic characterization indicated a predominant anthropogenic cycle of infection within the pediatric population studied. Integration of sequence typing data with information on geographic origins of samples allows parasite sub-population tracing using current typing tools.
十二指肠贾第虫是一种常见的鞭毛虫原生动物寄生虫，可感染多种脊椎动物宿主的小肠。本研究旨在利用来自埃及伊斯梅利亚省受感染牛、水牛和儿童的一组示例性样本，确定使用当前的基因分型工具对十二指肠贾第虫分离株进行溯源是否可行。
从191个牛群中收集了804份反刍动物粪便样本，以及165份10岁以下腹泻儿童的样本。使用粪便抗原RIDA®QUICK检测和实时荧光定量PCR在这些样本中检测寄生虫。然后根据磷酸丙糖异构酶、谷氨酸脱氢酶和β-贾第蛋白基因对样本进行基因特征分析。
十二指肠贾第虫在反刍动物中的感染率为53%，在有症状儿童中的感染率为21%，且感染与腹泻症状无正相关。序列分型分析证实，与A型序列相比，人类中B型序列占主导（>67%），反刍动物中E型序列占主导（>81%）。对于39个样本，可以获得三个标记基因片段的完整序列信息。将三个标记基因片段的串联序列信息与各个样本的空间数据相结合，结果显示，在5个案例中的4个案例中，相同或近乎相同（仅1358个碱基对中最多有一个不同）的串联测序类型在空间上相关。
即使在高流行地区，反刍动物引发人畜共患感染的风险也可忽略不计。基因特征分析表明，在所研究的儿科人群中，主要存在人为感染循环。将序列分型数据与样本地理来源信息相结合，可使用当前的分型工具追踪寄生虫亚群。
