High occurrence of Blastocystis sp. subtypes 1–3 and Giardia intestinalis assemblage B among patients in Zanzibar, Tanzania

Abstract

BackgroundBlastocystis is a common intestinal parasite with worldwide distribution but the distribution of Blastocystis and its subtypes in East Africa is largely unknown. In this study, we investigate the distribution of Blastocystis subtypes in Zanzibar, Tanzania and report the prevalence of intestinal parasites using both molecular methods and microscopy.MethodsStool samples were collected from both diarrhoeic and non-diarrhoeic outpatients in Zanzibar. In addition to microscopy, real-time PCR for Blastocystis, Entamoeba histolytica and E. dispar, Giardia intestinalis, Cryptosporidium spp., and Dientamoeba fragilis was used. Blastocystis subtypes were determined by a conventional PCR followed by partial sequencing of the SSU-rRNA gene. Genetic assemblages of Giardia were determined by PCR with assemblage specific primers.ResultsIntestinal parasites were detected in 85 % of the 174 participants, with two or more parasites present in 56 %. Blastocystis sp. and Giardia intestinalis were the most common parasites, identified by PCR in 61 and 53 % of the stool samples respectively, but no correlation between carriage of Blastocystis and Giardia was found. The Blastocystis subtype distribution was ST1 34.0 %, ST2 26.4 %, ST3 25.5 %, ST7 0.9 %, and 13.2 % were positive only by qPCR (non-typable). The Giardia genetic assemblages identified were A 6.5 %, B 85 %, A + B 4.3 %, and non-typable 4.3 %. The detection rate with microscopy was substantially lower than with PCR, 20 % for Blastocystis and 13.8 % for Giardia. The prevalence of Blastocystis increased significantly with age while Giardia was most prevalent in children two to five years old. No correlation between diarrhoea and the identification of Giardia, Blastocystis, or their respective genetic subtypes could be shown and, as a possible indication of parasite load, the mean cycle threshold values in the qPCR for Giardia were equal in diarrhoeic and non-diarrhoeic patients.ConclusionsCarriage of intestinal parasites was very common in the studied population in Zanzibar. The most commonly detected parasites, Blastocystis and Giardia, had different age distributions, possibly indicating differences in transmission routes, immunity, and/or other host factors for these two species. In the Blastocystis subtype analysis ST1-3 were common, but ST4, a subtype quite common in Europe, was completely absent, corroborating the geographical differences in subtype distributions previously reported.

Blastocystis genetic diversity among children of low-income daycare center in Southeastern Brazil

“…Globally, ST3 predominance has been observed in different geographic areas and populations, including in South America (David et al, 2015;Melo et al, 2017;Ramirez et al, 2014Ramirez et al, , 2016Sánchez et al, 2017). Otherwise, our results showed the predominance of ST1 (56.1%) and this observation concurs to findings of some particular investigations in Africa (Forsell et al, 2016), Asia (Sanpool et al, 2017;Thathaisong et al, 2013;Yoshikawa et al, 2016b) and in some countries in Latin America as Brazil, Colombia and Mexico (Malheiros et al, 2011;Ramirez et al, 2014;Villegas-Gómez et al, 2016). Even though ST3 was not the most prevalent subtype in the sampled population, its prevalence (31.6%) was relevant.…”

“…Very little data is currently available on human infections with ST6 and ST7. However, their presence has been revealed in Africa (Forsell et al, 2016), Asia (Palasuwan et al, 2016;Sanpool et al, 2017;Thathaisong et al, 2013;Yoshikawa et al, 2016b) and more recently in South America (David et al, 2015;Melo et al, 2017;Ramirez et al, 2016Ramirez et al, , 2017Sánchez et al, 2017).…”

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

“…is by far the most common single-celled eukaryote found in human faeces. Indeed, its prevalence in humans reaches or can greatly exceed 50% in many geographical regions, particularly in developing countries where faecal peril represents a major risk in link with poor sanitary conditions, hygiene practices and low-quality drinking water [4][5][6]. The question of the pathogenic potential and clinical significance of Blastocystis sp.…”

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

“…Blastocystis sp. is currently the most common single-celled intestinal parasite found in humans, since its prevalence can greatly exceed 50% in developing countries (El Safadi et al, 2014;Forsell et al, 2016) and reach an average of around 20% in industrialised regions of Europe (Bart et al, 2013;El Safadi et al, 2016). This protozoan has also been frequently found in many groups of animals, including non-human primates and various groups of mammals, birds, reptiles, amphibians and insects (Tan, 2004;Stensvold and Clark, 2016;Yoshikawa et al, 2016;Cian et al, 2017).…”