Genetic characterization of Blastocystis from poultry, livestock animals and humans in the southwest region of Iran—Zoonotic implications

Abstract

Blastocystis is the most common intestinal parasite found in epidemiological studies in Iran. The genus Blastocystis comprises multiple subtypes (ST), evincing the existence of extensive intrageneric diversity. Meanwhile, information on Blastocystis STs in domestic animals in Iran is limited. This study was designed to identify the prevalence and subtype distribution of Blastocystis in domestic animals and to evaluate the extent of zoonotic origin of human Blastocystis carriage. A total of 395 faecal samples from farm animals (220 from poultry, 100 from sheep and 75 from cattle) and 23 Blastocystis positive samples from humans (available from the previous report of this study and included for reference) from the Khuzestan province, southwestern Iran, were analysed. Standard parasitological methods and PCR‐based analysis of the SSU‐rRNA gene were used. Overall, 115 (29.1%; 95% CI, 26.5%–31.6%) of the animals were positive for Blastocystis sp. by parasitological methods. The highest colonization rate was found in cattle (50.6%, 38/75), followed by sheep (32.0%, 32/100) and poultry (20.4%, 45/220). Eight Blastocystis STs were identified among 55 sequenced isolates from animals (n = 32) and humans (n = 23): ST3 (27.3%), ST14 (25.4%), ST1 (12.7%), ST7 (12.7%), ST2 (9.1%), ST6 (7.3%), ST5 (3.6%) and ST10 (1.8%). Blastocystis ST1 and ST3 were found in both human and non‐human hosts, and examples of shared alleles (strains) were observed. Meanwhile, ST2 was observed only in humans, ST5 only in sheep, ST6 only in poultry and ST10 in only cattle. This is the most comprehensive report of Blastocystis STs in farm animals in Iran.

Genetic diversity of Blastocystis subtypes in the Alpine musk deer (Moschus chrysogaster) in Gansu province, northwestern China

“…Although ST14 and ST24 are often observed in various ruminant species, their presence in this study revealed that Blastocystis sp. is genetically diverse in the Alpine musk deer (Hublin et al, 2021;Maloney et al, 2019;Salehi et al, 2021). At least 13 Blastocystis STs (ST1-10, ST12, ST14, and ST24) have been identified in humans worldwide, with ST1-4 being the predominant STs and ST10, ST14, and ST24 indicating a zoonotic infection risk (Deng, Tay, et al, 2021;Jiménez et al, 2019;Khaled et al, 2020;Liu et al, 2021;Ma et al, 2020;Salehi et al, 2021).…”

“…is genetically diverse in the Alpine musk deer (Hublin et al, 2021;Maloney et al, 2019;Salehi et al, 2021). At least 13 Blastocystis STs (ST1-10, ST12, ST14, and ST24) have been identified in humans worldwide, with ST1-4 being the predominant STs and ST10, ST14, and ST24 indicating a zoonotic infection risk (Deng, Tay, et al, 2021;Jiménez et al, 2019;Khaled et al, 2020;Liu et al, 2021;Ma et al, 2020;Salehi et al, 2021). Moreover, seven STs (ST1-7) have been reported in patients in China till date (Li et al, 2021;Ma et al, 2020;Ning et al, 2020).…”

“…Although ST14 and ST24 are often observed in various ruminant species, their presence in this study revealed that Blastocystis sp. is genetically diverse in the Alpine musk deer (Hublin et al, 2021; Maloney et al, 2019; Maloney & Santín, 2021; Salehi et al, 2021).…”

The Presence of Blastocystis in Tibetan Antelope (Pantholops hodgsonii)

“…The overall infection rate of Blastocystis in Tibetan antelope was 4.8% (30/627) in Tibet, which was lower than the prevalence of 5.5% (6/109) and 6.0% (50/832) identified in sheep (Wang et al, 2018a;Li et al, 2018) in China and 19.3% (9/150) and 32.0% (32/100) in sheep in Iran (Rostami et al, 2020;Salehi et al, 2021). The difference in the prevalence of Blastocystis may be related to the living environment and geographical factors of different countries (Tan, 2008).…”

“…However, the existing data indicate that sheep may carry several potential Blastocystis subtypes, including ST1, ST3, ST4, ST5, ST6, and ST7 ( Tan et al., 2013 ; Song et al., 2017 ; Wang et al., 2018a ; Salehi et al., 2021 ). So far, studies on the prevalence and subtype diversity of Blastocystis in Tibetan antelope are unknown and the relevant public health impact is still unclear.…”