Department of Parasitology and Mycology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Int J Hyg Environ Health. 2018 May;221(4):642-651. doi: 10.1016/j.ijheh.2018.03.007. Epub 2018 Mar 16.
Human-infecting microsporidia are a group of spore-forming eukaryotic microorganisms that can infect both animals and humans. Recent evidences indicate waterborne transmission of microsporidia spores to human via either drinking water or irrigation of vegetable farms with contaminated water resources. The current study aimed to evaluate the presence of human-infecting microsporidia in treated wastewater (TW) and vegetable farms irrigated with treated wastewater during a year.
Totally, twelve samples of each treated wastewater and vegetables were collected. In order to recover microsporidia spores, filtration using cellulose nitrate membrane (pore size 0.4 μm) and sedimentation were employed. DNA extraction was performed for all samples and genus/species were characterized using specific primers. In order to characterize genotypes, ITS fragment of E. bieneusi was amplified, sequenced and compared in GenBank database. Phylogenetic tree was employed to analysis the probable correlation between obtained genotypes with those E. bieneusi genotypes, which were previously obtained from human and animals from same region.
After nested PCR, expected fragments of E. bieneusi and Encephalitozoon spp were observed among 5/12 (41.7%) and 1/12 (8.33%) of vegetable samples, respectively. From total of 12 TW samples, expected fragments of E. bieneusi and Encephalitozoon spp were amplified among 7/12 (53.8%) and 1/12 (8.33%) of TW samples, respectively. Genotypes D and E were characterized from both TW and vegetables samples. Phylogenetic analysis showed close-relationship between E. bieneusi from TW and vegetable samples with E. bieneusi from animals and humans obtained from the same region.
Our findings suggested the key role of animals in epidemiology of zoonotic transmission of E. bieneusi. Moreover, our findings revealed the occurrence of human-infecting microsporidia in treated wastewater because of either insufficiency of treatment process or distribution of microsporidia spores in wastewater treatment plant via animals.
感染人类的微孢子虫是一组形成孢子的真核微生物，可感染动物和人类。最近的证据表明，微孢子虫孢子通过饮用水或受污染水资源灌溉的蔬菜农场，以水传播的方式感染人类。本研究旨在评估在一年中，受处理废水（TW）和用处理废水灌溉的蔬菜农场中是否存在感染人类的微孢子虫。
总共采集了 12 个 TW 样本和 12 个蔬菜样本。为了回收微孢子虫孢子，采用纤维素硝酸酯膜（孔径 0.4μm）过滤和沉淀法。对所有样本进行 DNA 提取，并使用特异性引物对属/种进行鉴定。为了鉴定基因型，扩增、测序并在 GenBank 数据库中比较了肠微孢子虫的 ITS 片段。采用系统发育树分析了从同一地区的人类和动物中获得的与获得的肠微孢子虫基因型之间的可能相关性。
巢式 PCR 后，在 5/12（41.7%）和 1/12（8.33%）的蔬菜样本中观察到肠微孢子虫和脑炎微孢子虫的预期片段，在 12 个 TW 样本中，在 7/12（53.8%）和 1/12（8.33%）的 TW 样本中扩增出肠微孢子虫和脑炎微孢子虫的预期片段。从 TW 和蔬菜样本中鉴定出基因型 D 和 E。系统发育分析显示，TW 和蔬菜样本中的肠微孢子虫与同一地区从动物和人类中获得的肠微孢子虫密切相关。
我们的研究结果表明，动物在肠微孢子虫的人畜共患病传播流行病学中起着关键作用。此外，我们的研究结果表明，由于处理过程不足或微孢子虫孢子在废水处理厂中通过动物分布，受处理废水可能存在感染人类的微孢子虫。
