Prevalence and subtype distribution of Blastocystis sp. isolates from poultry in Lebanon and evidence of zoonotic potential

Abstract

BackgroundBlastocystis sp. is a common protozoan parasite frequently identified in the digestive tract of humans and a large variety of animal hosts worldwide, including birds. It exhibits a large genetic diversity with the identification of 17 subtypes (STs), most of them with low host specificity. ST6 and ST7 were identified in birds and suggested to represent avian STs only in the context of scarce small-scale epidemiological surveys. Moreover, these two STs also account for a significant proportion of human infections whose zoonotic origin has never been clearly confirmed. Therefore, molecular screening of Blastocystis sp. was conducted by quantitative real-time PCR for fecal samples from poultry farms and their in-contact humans from slaughterhouses in Lebanon. In parallel, a control group consisting of patients hospitalized in the same geographical area and reporting no contact with poultry was also screened for the presence of the parasite.ResultsThe overall prevalence of Blastocystis sp. was shown to reach around 32% in chicken samples and 65% in the farms screened. All the avian isolates were subtyped and belonged to either ST6 or ST7, with a large predominance of ST6. Fifty-four percent of slaughterhouse staff members were positive for Blastocystis sp. compared with a similar prevalence of 56% in hospitalized patients. ST3 was predominant in both human cohorts followed by either ST1 then ST2 among slaughterhouse staff or by ST2 then ST1 among hospitalized patients. ST6 was also identified in two slaughterhouse workers and not in the group of hospitalized patients. Gene sequence identity was observed between chicken and human ST6 isolates from the same slaughterhouse.ConclusionsOur data revealed a high prevalence of Blastocystis sp. in chicken samples and confirmed that ST6 and ST7 represented avian-adapted STs. Among both human cohorts, Blastocystis sp. infection was shown to exceed 50% with a predominance of ST3. The identification of ST6 in slaughterhouse staff members confirmed the zoonotic transmission of this ST through repeated and direct contact between chickens and their handlers.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-2975-5) contains supplementary material, which is available to authorized users.

First report on the prevalence and subtype distribution of Blastocystis sp. in dairy cattle in Lebanon and assessment of zoonotic transmission

“…Moreover, although the number of samples analysed in each cohort remained limited, the distribution of the different STs was not significantly different between the two human groups (Fisher's exact test, P = 0.67). Strikingly, this distribution with predominance of ST3 followed by either ST1 or ST2 was also similar to that observed in previous studies conducted recently among patients at the same hospital in Tripoli, staff members working in poultry slaughterhouses in North Lebanon (Greige et al, 2018) and among schoolchildren in Tripoli (Osman et al, 2016).…”

“…For instance, ST5 frequently infects pigs (Wang et al, 2014), whereas ST6 and ST7 are predominant in birds (Cian et al, 2017). Based on largescale epidemiological surveys, these last STs were considered to be pig-and avian-adapted STs respectively, and corresponding isolates were shown to be possibly transmitted from these animals to their in-contact workers at intensive commercial piggeries and poultry slaughterhouses (Wang et al, 2014;Greige et al, 2018). In addition, ST8, which is common in non-human primates, was identified with unexpected high prevalence in their keepers (Stensvold et al, 2009).…”

First Report on the Prevalence and Subtype Distribution of Blastocystis sp. in Edible Marine Fish and Marine Mammals: A Large Scale-Study Conducted in Atlantic Northeast and on the Coasts of Northern France

“…(CH-II-7 IC, CH-II-7 IE, CH-II-8 IC, CH-II-1 SIE, PV-IV-3 IC, PV-V-9 IC, SS-III-1 IC) exhibited 100% identity with each other and corresponded to isolates identified in three different fish species (herring, saithe and mackerel) caught in two different geographical areas (Eastern English Channel and Northern North Sea). These sequences showed only 92% identity with those of ST10 isolates found in Artiodactyla and mainly bovid, which are considered as natural hosts of this ST [16,22,24,37,38], but were identical to that of the untypable isolate ZLC7 identified in a reptile (Boa constrictor) housed in the zoo of Lille in France [16]. As shown in our phylogenetic tree, these 7 sequences emerged at the basis of a large group including, more specifically, the reptilian cluster NMAST II with BP and BPP of 50% and 0.90 respectively, and formed a sister group with reptilian isolates belonging to NMAST III.…”

“…Indeed, several evidences support the zoonotic potential of Blastocystis sp. such as the unusual high prevalence of the ST8, probably of animal origin, amongst zoo-keepers [19,20], as well as the sequence identity of ST5 isolates from pigs and piggery workers [21] and of ST6 isolates from poultry and slaughterhouse staff [22]. These data strongly suggest that repeated and direct contact between animals and their handlers could promote the transmission of Blastocystis sp.…”

“…Indeed, the SSU rDNA sequence of this isolate showed 98% identity with homologous sequences from human and avian isolates. This ST together with ST6 are considered as avian STs because of their predominance in birds and were shown to be transmissible to humans by a zoonotic route [9,16,17,22,36]. Consequently, the single fish presenting Blastocystis sp.…”