Department of Environmental Health Sciences and Technology, Jimma University, Jimma, Ethiopia.
Department of Biology, Faculty of Science and Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium.
Infect Dis Poverty. 2018 Mar 5;7(1):17. doi: 10.1186/s40249-018-0397-4.
Giardia duodenalis is a species complex consisting of multiple genetically distinct assemblages. The species imposes a major public health crisis on developing countries. However, the molecular diversity, transmission dynamics and risk factors of the species in these countries are indeterminate. This study was conducted to determine the molecular epidemiology of G. duodenalis infection in asymptomatic individuals in Southern Ethiopia.
From March to June 2014, fresh stool samples were collected from 590 randomly selected individuals. Socio-demographic data were gathered using a pre-tested structured questionnaire. The genotyping was done using triosephosphate isomerase gene-based nested polymerase chain reaction and DNA sequencing. The genetic identity and relatedness of isolates were determined using the basic local alignment search tool and phylogenetic analysis. Risk factors associated with G. duodenalis infection were analysed using binary and multinomial logistic regression models.
The results showed that 18.1% (92/509) of the study subjects were infected by G. duodenalis. Among the isolates, 35.9% (33/92) and 21.7% (20/92) were sub-typed into assemblages A and B, respectively, whereas 42.4% (39/92) showed mixed infections of A and B. Most of the assemblage A isolates (94%,31/33) were 100% identical to sequences registered in GenBank, of which the majority belonged to sub-assemblage AII. However, the high genetic variability and frequency of double peaks made sub-genotyping of assemblage B more problematic and only 20% (4/20) of the isolates matched 100% with the sequences. The risk factors of age (P = 0.032) and type of drinking water source (P = 0.003) both showed a significant association with the occurrence G. duodenalis infection.
This study established the endemicity of G. duodenalis in Southern Ethiopia. Infection with assemblage A was more frequent than with assemblage B, and the rate of infection was higher in children and in municipal/tap and open spring water consumers than the other groups. Sub-typing of assemblage B and determining the origin of double peaks were challenging. The present study confirms the need for further inclusive studies to be conducted focusing on sub-types of assemblage B and the origin of heterogeneity.
十二指肠贾第鞭毛虫是一个由多个遗传上不同的组合组成的种复合体。该物种对发展中国家构成了重大的公共卫生危机。然而，这些国家的种的分子多样性、传播动态和危险因素尚不确定。本研究旨在确定埃塞俄比亚南部无症状个体中十二指肠贾第鞭毛虫感染的分子流行病学。
2014 年 3 月至 6 月，从 590 名随机选择的个体中采集新鲜粪便样本。使用预先测试的结构化问卷收集社会人口统计学数据。使用三磷酸甘油异构酶基因巢式聚合酶链反应和 DNA 测序进行基因分型。使用基本局部比对搜索工具和系统发育分析确定分离株的遗传同一性和相关性。使用二项和多项逻辑回归模型分析与 G. duodenalis 感染相关的危险因素。
结果表明，509 名研究对象中有 18.1%（92/509）感染了 G. duodenalis。在分离株中，35.9%（33/92）和 21.7%（20/92）分别分为 A 和 B 亚群，而 42.4%（39/92）显示 A 和 B 的混合感染。大多数 A 亚群分离株（94%，31/33）与 GenBank 中注册的序列完全相同，其中大多数属于亚群 AII。然而，高遗传变异性和双峰频率使得 B 亚群的亚分型更加困难，只有 20%（4/20）的分离株与序列完全匹配。年龄（P=0.032）和饮用水源类型（P=0.003）是两个与 G. duodenalis 感染发生显著相关的危险因素。
本研究确定了 G. duodenalis 在埃塞俄比亚南部的流行情况。A 亚群的感染比 B 亚群更为常见，且儿童和市政/自来水和开放泉水消费者的感染率高于其他群体。B 亚群的亚分型和确定双峰的来源具有挑战性。本研究证实需要进一步开展包容性研究，重点关注 B 亚群的亚型和异质性的来源。
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