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

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.

Marked genetic diversity within Blastocystis in Australian wildlife revealed using a next generation sequencing–phylogenetic approach

“…Clearly, caution is warranted in making conclusions about an affiliation with a particular animal species in a captive environment, such as in parks, zoos or breeding/production facilities, due to cross transmission events of Blastocystis among species. There are also reports of ST13 in cervids in China, South Korea and UK ( Alfellani et al, 2013 ; Betts et al, 2018 ; Wang et al, 2018 ; Kim et al, 2020 ; Li et al, 2020 ; Chen et al, 2021 , 2022 ) and from primates in Bangladesh, China and Poland ( Li et al, 2019 ; Rudzińska et al, 2021 ; Geng, 2021- unpublished; Li et al, 2022 - unpublished), but none of these studies has provided sequence for >80% of the SSU-rRNA gene. Other key STs recorded in kangaroos and wallabies in previous studies include ST12, in the western grey kangaroo and northern swamp wallaby from zoos ( Parkar et al, 2010 ) and ST16, in red kangaroos from a zoo (Yoshikawa, 2011 - unpublished) (cf.…”

“…Although some studies have tested faecal samples from these three species of deer for Blastocystis , most animal were captive (e.g., in zoos or on farms) (see Supplementary file 5 for references). An exception is a study conducted in the Sichuan Wolong National Natural Reserve in Southwest China, in which 8 (of 39 tested) wild sambar deer harboured Blastocystis ST13 and/or ST14 ( Chen et al, 2021 ). However, the validity of ST13 is in question because <80% of the SSU-rRNA gene was sequenced (cf.…”