Genetic Diversity of Blastocystis in Livestock and Zoo Animals

Abstract

23Blastocystis is a common unicellular anaerobic eukaryote that inhabits the large intestine of 24 many animals worldwide, including humans. The finding of Blastocystis in faeces in 25 mammals and birds has led to proposals of zoonotic potential and that these hosts may be the 26 source of many human infections. Blastocystis is, however, a genetically diverse complex of 27 many distinct organisms (termed subtypes; STs), and sampling to date has been limited, both 28 geographically and in the range of hosts studied. In order to expand our understanding of host 29 specificity of Blastocystis STs, 557 samples were examined from various non-primate animal 30 hosts and from a variety of different countries in Africa, Asia and Europe. STs were 31 identified using 'barcoding' of the small subunit rRNA gene using DNA extracted either 32 from culture or directly from faeces. The host and geographic range of several STs has 33 thereby been greatly expanded and the evidence suggests that livestock is not a major 34 contributor to human infection. Two new STs were detected among the barcode sequences 35 obtained; for these, and for three others where the data were incomplete, the corresponding 36 genes were fully sequenced and phylogenetic analysis was undertaken. 37 38

Prevalence and genetic diversity of Blastocystis in family units living in the United States

“…Blastocystis is a single-celled microbial eukaryote that is commonly found in the intestinal tract of a diverse range of non-mammalian and mammalian hosts including humans Alfellani et al, 2013a;Tan, 2008). As a consequence of the controversial and unresolved role of Blastocystis in human intestinal disease and the increased awareness of the importance of the gut microbiome (and specific components of the gut microbiome) in human health and disease, research into Blastocystis has increased greatly in recent years (Andersen and Stensvold, 2015;Guinane and Cotter, 2013;Roberts et al, 2014;Scanlan, 2012;Scanlan and Stensvold, 2013;Sekirov et al, 2010).…”

“…Firstly, there is some evidence of zoonotic transmission; however, this is most likely to occur only in certain circumstances and for specific subtypes (STs), e.g. close contact with animals that are host to subtypes that can also colonise humans (Alfellani et al, 2013a;Parkar et al, 2010;Wang et al, 2014). Secondly, environmental sources such as drinking water may also be a potential source of Blastocystis (Leelayoova et al, 2008;Taamasri et al, 2000).…”

Prevalence and Subtype Identification of Blastocystis sp. in Healthy Individuals in the Tunis Area, Tunisia

“…9 At the molecular level, the genus Blastocystis exhibits a large genetic diversity since at least 17 different ribosomal lineages so-called subtypes (STs) were identified. 10 Nine of them (ST1-ST9) were found in humans with varying prevalence. 11 In most countries worldwide, ST3 is globally predominant followed by ST1 and ST2, whereas ST4 is rarely found outside Europe.…”

“…Interestingly, almost all of these nine human STs are also shared by various nonhuman hosts, highlighting both the low host specificity of the parasite and its zoonotic potential. 10 In spite of the potential impact of Blastocystis sp. in public health, few reports are available on the prevalence and ST distribution of the parasite in some geographical regions including Maghreb.…”

Frequency of Blastocystosis and Its Association with Clinical Symptoms in 2 Years of Surveillance at "Pedro Kourí" Institute

“…This protozoan exhibits extensive genetic diversity, and on the basis of molecular analysis of the small subunit RNA gene, up to 17 subtypes have been described with subtype (ST) 1-9 being found in humans, and ST3 is the predominant ST found in most human epidemiological studies [34].…”