Blastocystis sp. Prevalence and Subtypes Distribution amongst Syrian Refugee Communities Living in North Lebanon

Abstract

Molecular data concerning the prevalence and subtype (ST) distribution of the intestinal parasite Blastocystis sp. remain scarce in the Middle East. Accordingly, we performed the first molecular epidemiological survey ever conducted in the Syrian population. A total of 306 stool samples were collected from Syrian refugees living in 26 informal tented settlements (ITS) subjected or not to water, sanitation, and hygiene (WASH) interventions in North Lebanon, then screened for the presence of Blastocystis sp. by real-time polymerase chain reaction followed by subtyping. The overall prevalence of the parasite was shown to reach 63.7%. Blastocystis sp. colonization was not significantly associated with gender, age, symptomatic status, abdominal pain or diarrhea. In contrast, WASH intervention status of ITS was identified as a risk factor for infection. Among a total of 164 subtyped isolates, ST3 was predominant, followed by ST1, ST2, and ST10. No particular ST was reported to be associated with age, gender, symptomatic status, digestive disorders, or WASH intervention status of ITS. Intra-ST diversity of ST1 to ST3 was low suggesting large-scale anthroponotic transmission. Moreover, comparative analysis of ST1 to ST3 genotypes revealed that the circulation of the parasite between Syrian refugees and the host population was likely limited.

Infection with Blastocystis spp. and its association with enteric infections and environmental enteric dysfunction among slum-dwelling malnourished adults in Bangladesh

“…These observations support the historical findings on abundance of Blastocystis in developing countries owing to poor personal hygiene, unsanitary living conditions, consumption of contaminated food and water, and exposure to animals [9,27,28]. Moreover, the prevalence of Blastocystis reported in this study is consistent with previous studies done in developing world [4,29,30]. Blastocystis is transmitted through fecal-oral route.…”

Detection, Molecular Identification and Transmission of the Intestinal Protozoa Blastocystis sp. in Guinea from a Large-Scale Epidemiological Study Conducted in the Conakry Area

“…To complete our data and taking advantage of the large number of isolates subtyped in the present survey, the intra-ST variation observed within the 3 major STs identified in the Guinean population was analyzed. This analysis succeeded those recently performed in Senegal [10] and among Syrian refugees leaving in North Lebanon [41] using the same molecular marker and comparing the sequence of the same amplified domain. By first determining the genotypes for each of these 3 STs through the identification of the variable positions between sequences of isolates belonging to the same ST and, then, by establishing the ratio of the number of isolates per genotype, it was shown that ST3 exhibited the lowest intra-ST diversity followed by ST2 and ST1 in the Senegalese and Syrian cohorts [10,41].…”

“…The amplified fragment of approximately 300 bp length of the SSU rDNA gene has been shown to contain sufficient sequence information for accurate subtyping of Blastocystis sp. isolates [10,13,38,41,44]. Both positive (DNA obtained from Blastocystis sp.…”

“…Additionally, the sequences of Blastocystis sp. isolates belonging to ST1, ST2 or ST3 were aligned with each other using the BioEdit v7.0.1 package (date of release 10 June 2019; http://www.mbio.ncsu.edu/BioEdit/bioedit.html, accessed on 12 January 2022) to determine intra-ST diversity and identify so-called genotypes referring to genetically distinct strains within the same ST [10,41].…”

“…To complete this overview, various isolates identified in amphibians, reptiles, fish and insects and representative of the so-designed non-mammalian and avian STs (NMASTs) could also greatly expand the molecular heterogeneity observed in this genus [3,4,38]. Among all the STs identified, only 12 (ST1 to ST9, ST10, ST12 and ST14) were so far isolated from human stool with varying prevalence [10,[39][40][41]. Indeed, ST1 to ST4 comprise more than 90% of all subtyped isolates around the world, with ST3 predominating in most countries [17,39].…”