Prevalence, risk factors for infection and subtype distribution of the intestinal parasite Blastocystis sp. from a large-scale multi-center study in France

Abstract

BackgroundBlastocystis sp. is the most common intestinal parasite of humans. Despite its potential public health impact, epidemiological data regarding the prevalence and molecular subtype distribution of Blastocystis sp. in Europe are rarely reported. Therefore, the first multi-center epidemiological survey performed in Europe was conducted in France to diagnose and subtype Blastocystis sp. and to identify risk factors for infection.MethodsStool samples from 788 patients were collected either in summer or winter in 11 hospitals throughout France together with patient data. All stool samples were tested for the presence of Blastocystis sp. by quantitative PCR targeting the SSU rDNA gene. Positive samples were sequenced to determine the distribution of the subtypes in our cohort. Statistical analyses were performed to identify potential risk factors for infection.ResultsUsing quantitative PCR, the overall prevalence of Blastocystis sp. was shown to reach 18.1 %. The prevalence was significantly higher in summer (23.2 %) than in winter (13.7 %). Travellers or subjects infected with other enteric parasites were significantly more infected by Blastocystis sp. than non-travellers or subjects free of other enteric parasites, respectively. Different age-related epidemiological patterns were also highlighted from our data. The prevalence of Blastocystis sp. was not significantly higher in patients with digestive symptoms or diagnosed with chronic bowel diseases. Among symptomatic patients, Blastocystis sp. infection was significantly associated with abdominal pain. Gender, socioeconomic status, and immune status were not identified as potential risk factors associated with infection. Among a total of 141 subtyped isolates, subtype 3 was predominant (43.3 %), followed by subtype 1 and subtype 4 (20 %), subtype 2 (12.8 %), subtype 6 and subtype 7 (2.1 %). No association between ST and clinical symptoms was statistically evidenced.ConclusionsA high prevalence of Blastocystis sp. infection was found in our French patient population. Seasonal impact on the prevalence of Blastocystis sp. was highlighted and recent travels and age were identified as main risk factors for infection. Most cases were caused by subtypes 1 to 4, with a predominance of subtype 3. Large variations in both prevalence and ST distribution between hospitals were also observed, suggesting distinct reservoirs and transmission sources of the parasite.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1776-8) contains supplementary material, which is available to authorized users.

Epidemiology and Prevalence of Blastocystis spp. in North Cyprus

“…in developed countries such as Japan (0.5%) 17 and Denmark (5.6%) 18 is relatively low, with the exception of France (13.7-23.1%). 20 On the contrary, generally higher rates are 30 and Thailand (21%). 31 The highest percentages of Blastocystis spp.…”

“…varies between 0.5% and 23.1% in developed countries and 22.1% and 100.0% in developing countries. 1,2,[15][16][17][18][19][20] Generally, the high prevalence of infection is associated with demographic, socioeconomic, and epidemiological factors. 1,15,21,22 Although a large number of studies on Blastocystis spp.…”

Molecular Epidemiology of Blastocystis sp. in Various Animal Groups from Two French Zoos and Evaluation of Potential Zoonotic Risk

“…This domain of the SSU-rDNA gene has been shown to provide sufficient information for differentiating STs of Blastocystis sp. [5,38]. DNA extraction controls (isolation of DNAs without stool and from a Blastocystis sp.-negative stool) subsequently used in qPCR assays and positive (DNA obtained from Blastocystis sp.…”

“…is an enteric protist with a worldwide distribution belonging to the group Stramenopiles and currently identified as one of the most common single-celled eukaryotes found in human stool samples [1–3]. Indeed, its prevalence can reach an average of 20% in industrialized countries [4,5] and can largely exceed 50% in developing countries [6]. A recent study even showed a prevalence of 100% in a cohort of children living in a rural area of Senegal [7].…”

Occurrence and subtype distribution of Blastocystis sp. in humans, dogs and cats sharing household in northern Spain and assessment of zoonotic transmission risk

“…The role of Blastocystis as a pathogen in humans is still the focus of intense debate. While some studies have found no link between Blastocystis and disease (Leder, Hellard, Sinclair, Fairley, & Wolfe, ; Ozyurt et al, ), there is some evidence from epidemiological (El Safadi et al, ; Mohamed et al, ), in vitro (Puthia, Lu, & Tan, ) and in vivo (Elwakil & Hewedi, ) surveys supporting the pathogenic potential of the parasite. Thus, the presence of Blastocystis has been associated with gastrointestinal disorders (Roberts, Stark, Harkness, & Ellis, ), irritable bowel syndrome (Boorom et al, ) and cutaneous lesions (Balint et al, ).…”