Genetic characterization and zoonotic potential of Blastocystis from wild animals in Sichuan Wolong National Natural Reserve, Southwest China.

Zhijun Zhong,Yuehong Cheng,Ziyao Zhou,Yijun Chai,Tingmei He,Liuhong Shen,Haifeng Liu,Lei Deng,Shanyu Chen,Hualin Fu,Kun Zhang,Xiaogang Shi,Wanyu Meng,Guangneng Peng

doi:10.1051/parasite/2021071

Abstract

Blastocystis is a prevalent eukaryotic parasite that has been identified in a wide range of hosts. Several species are considered potential sources of Blastocystis infection in humans, but little is known about the prevalence of Blastocystis in wild animals. In this study, the prevalence and subtypes of Blastocystis were investigated to assess the zoonotic potential of wild animals in Sichuan Wolong National Natural Reserve. A total of 300 fecal samples were collected from 27 wildlife species in three areas of the Reserve. The subtype (ST), genetic characteristics, and prevalence of Blastocystis were determined by PCR amplification of part (~600 bp) of the SSU rRNA gene. Thirty fecal samples (10.0%) were Blastocystis-positive. The highest prevalence of Blastocystis was found in Yinchanggou (18.3%), with significantly less found in Niutoushan (7.5%) and Genda (5.5%) (p < 0.05). No significant differences were associated with different orders of animals in prevalence, which may be because of the small number of positive samples obtained. Sequence analysis showed five subtypes (ST1, ST3, ST5, ST13, and ST14), with ST13 and ST14 being predominant (33% each), followed by ST1 (20%). This is the first molecular investigation of Blastocystis infection in the wild animals of southwestern China. Subtypes ST1, ST3, ST5, and ST14 have previously been identified in humans, suggesting that wild animals may be potential reservoirs of Blastocystis for humans.

Highlights

The enteric parasite Blastocystis is the most common protist found in humans [34]
The prevalence of Blastocystis in the wild animals examined in this study was 10.0% (30/300); this is lower than that previously found in zoo animals in Western Australia (42%, 32/76) [25], wild animals on Qinling Mountains, China (40.2%, 200/497) [42], zoo animals in Japan (39.0%, 46/118) [2], wild animals in Brazil (34.4%, 115/334) [35], zoo animals in the United Kingdom (34.2%, 79/231), various captive animals in France (32.2%, 99/307) [12], captive wildlife in four zoos of southwestern China (15.7%, 66/420) [15], and captive mammalian wildlife in Bangladesh National Zoo (15.5%, 31/200) [29]
This study has identified the potential for transmission of Blastocystis infection between humans and Artiodactyla

Summary

Introduction

The enteric parasite Blastocystis (classified as a Stramenopile) is the most common protist found in humans [34]. There is strong evidence to suggest that some human infections may be caused by the zoonotic transmission of Blastocystis [25, 36]. The pathogenicity of Blastocystis remains controversial, with studies associating it with various gastrointestinal disorders such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) [9, 16, 18]. The few microbiome studies on this organism have indicated that Blastocystis is a common commensal in the human gut and is associated with increased bacterial diversity [6]. Subtypes ST1–10, ST12, and ST14 have been found in humans with varying prevalence, but ST1–4 are the most common, accounting for more than 90% of human Blastocystis infections [20, 26, 33]. Accumulating evidence has shown that the same subtype of Blastocystis can colonize a wide range of hosts, implying that these subtypes lack host-specific features

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