Dima El Safadi

Colonization with the enteric protozoa Blastocystis is associated with increased diversity of human gut bacterial microbiota

Alterations in the composition of commensal bacterial populations, a phenomenon known as dysbiosis, are linked to multiple gastrointestinal disorders, such as inflammatory bowel disease and irritable bowel syndrome, or to infections by diverse enteric pathogens. Blastocystis is one of the most common single-celled eukaryotes detected in human faecal samples. However, the clinical significance of this widespread colonization remains unclear, and its pathogenic potential is controversial. To address the issue of Blastocystis pathogenicity, we investigated the impact of colonization by this protist on the composition of the human gut microbiota. For that purpose, we conducted a cross-sectional study including 48 Blastocystis-colonized patients and 48 Blastocystis-free subjects and performed an Ion Torrent 16S rDNA gene sequencing to decipher the Blastocystis-associated gut microbiota. Here, we report a higher bacterial diversity in faecal microbiota of Blastocystis colonized patients, a higher abundance of Clostridia as well as a lower abundance of Enterobacteriaceae. Our results contribute to suggesting that Blastocystis colonization is usually associated with a healthy gut microbiota, rather than with gut dysbiosis generally observed in metabolic or infectious inflammatory diseases of the lower gastrointestinal tract.

Prevalence and Risk Factors for Intestinal Protozoan Infections with Cryptosporidium, Giardia, Blastocystis and Dientamoeba among Schoolchildren in Tripoli, Lebanon

Background Intestinal protozoan infections are confirmed as major causes of diarrhea, particularly in children, and represent a significant, but often neglected, threat to public health. No recent data were available in Lebanon concerning the molecular epidemiology of protozoan infections in children, a vulnerable population at high risk of infection. Methodology and Principal Findings In order to improve our understanding of the epidemiology of intestinal pathogenic protozoa, a cross-sectional study was conducted in a general pediatric population including both symptomatic and asymptomatic subjects. After obtaining informed consent from the parents or legal guardians, stool samples were collected in January 2013 from 249 children in 2 schools in Tripoli, Lebanon. Information obtained from a standard questionnaire included demographic characteristics, current symptoms, socioeconomic status, source of drinking water, and personal hygiene habits. After fecal examination by both microscopy and molecular tools, the overall prevalence of parasitic infections was recorded as 85%. Blastocystis spp. presented the highest infection rate (63%), followed by Dientamoeba fragilis (60.6%), Giardia duodenalis (28.5%) and Cryptosporidium spp. (10.4%). PCR was also performed to identify species and genotypes of Cryptosporidium, subtypes of Blastocystis, and assemblages of Giardia. Statistical analysis using a logistic regression model showed that contact with family members presenting gastrointestinal disorders was the primary risk factor for transmission of these protozoa. Conclusions This is the first study performed in Lebanon reporting the prevalence and the clinical and molecular epidemiological data associated with intestinal protozoan infections among schoolchildren in Tripoli. A high prevalence of protozoan parasites was found, with Blastocystis spp. being the most predominant protozoans. Although only 50% of children reported digestive symptoms, asymptomatic infection was observed, and these children may act as unidentified carriers. This survey provides necessary information for designing prevention and control strategies to reduce the burden of these protozoan infections, especially in children.

Molecular epidemiology of Blastocystis in Lebanon and correlation between subtype 1 and gastrointestinal symptoms.

Blastocystis is the most common eukaryotic parasite in the intestinal tract of humans. Because of its potential impact in public health, we acquired the first data concerning the prevalence of this parasite and the frequency of the Blastocystis subtypes (STs) in the Lebanese population. In this study, fecal samples from 220 Lebanese symptomatic and asymptomatic patients were collected and a total of 42 patients (19%) were identified as positive for this parasite by direct-light microscopy of smears. Among these, 36 Blastocystis isolates were genotyped using partial small subunit ribosomal RNA gene sequencing. The ST distribution in the present Lebanese population was as follows: ST3 (33.3%), ST2 (33.3%), ST1 (30.6%), and ST4 (2.8%). These data were compared with those available in other Middle Eastern and neighboring countries. Finally, ST1 was significantly more prevalent among symptomatic patients of this Lebanese population.

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

Blastocystis sp. is a common intestinal parasite infecting humans and a wide range of animals worldwide. It exhibits an extensive genetic diversity and 17 subtypes (STs) have thus far been identified in mammalian and avian hosts. Since several STs are common to humans and animals, it was proposed that a proportion of human infections may result from zoonotic transmission. However, the contribution of each animal source to human infection remains to be clarified. Therefore, the aim of this study was to expand our knowledge of the epidemiology and host specificity of this parasite by performing the largest epidemiological survey ever conducted in animal groups in terms of numbers of species screened. A total of 307 stool samples from 161 mammalian and non-mammalian species in two French zoos were screened by real-time PCR for the presence of Blastocystis sp. Overall, 32.2% of the animal samples and 37.9% of the species tested were shown to be infected with the parasite. A total of 111 animal Blastocystis sp. isolates were subtyped, and 11 of the 17 mammalian and avian STs as well as additional STs previously identified in reptiles and insects were found with a varying prevalence according to animal groups. These data were combined with those obtained from previous surveys to evaluate the potential risk of zoonotic transmission of Blastocystis sp. through the comparison of ST distribution between human and animal hosts. This suggests that non-human primates, artiodactyls and birds may serve as reservoirs for human infection, especially in animal handlers. In contrast, other mammals such as carnivores, and non-mammalian groups including reptiles and insects, do not seem to represent significant sources of Blastocystis sp. infection in humans. In further studies, more intensive sampling and screening of potential new animal hosts will reinforce these statements and expand our understanding of the circulation of Blastocystis sp. in animal and human populations.

Prevalence and genetic diversity of the intestinal parasites Blastocystis sp. and Cryptosporidium spp. in household dogs in France and evaluation of zoonotic transmission risk

Several parasites including the protozoa Blastocystis sp. and Cryptosporidium spp. may be causative agents of gastrointestinal symptoms in domestic dogs, and there may be a potential risk of transmission to owners. While France is one of the largest European countries in terms of its canine population, little data is available about the molecular epidemiology of these two parasites. The purpose of this study was to determine the prevalence of intestinal parasites in household dogs in France, and to evaluate the zoonotic risk of Blastocystis sp. and Cryptosporidium spp. by genotyping the corresponding isolates. To this end, 116 faecal samples were collected from household dogs regardless of breed, age or gender, living in the Lyons area, France. Various intestinal protozoa and helminths were identified by light microscopy. Screening for Blastocystis sp. and Cryptosporidium spp. were subsequently performed by PCR targeting the small subunit (SSU) rDNA coding region, followed by direct sequencing of the PCR products and analysis of the sequences obtained for genotyping. The overall prevalence of dogs infected with at least one gastrointestinal parasite was 42.2% (49/116). After light microscopy examination of faecal samples, the most common parasites found were the protozoa Giardia sp. (25.0%) and Cystoisospora sp. (19.8%). Using molecular methods, four dogs (3.4%) were shown to be infected by Blastocystis sp. and carried either subtype (ST) 2, commonly identified in various animal groups, or ST10, frequently found in bovids. Three dogs (2.6%) were positive for C. canis, infecting humans episodically. The low prevalence of both parasites, combined with the identification of C. canis and Blastocystis sp. ST2 and ST10 in the canine population, strongly suggests that dogs play a negligible role as zoonotic reservoirs for both parasites and do not seem to be natural hosts of Blastocystis sp.

Acute Blastocystis-Associated Appendicular Peritonitis in a Child, Casablanca, Morocco

Despite increasing reports that Blastocystis infection is associated with digestive symptoms, its pathogenicity remains controversial. We report appendicular peritonitis in a 9-year-old girl returning to France from Morocco. Only Blastocystis parasites were detected in stools, appendix, peritoneal liquid, and recto-uterine pouch. Simultaneous gastroenteritis in 26 members of the child’s family suggested an outbreak.

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

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.

Prevalence, transmission, and host specificity of Cryptosporidium spp. in various animal groups from two French zoos

Cryptosporidium represents a major cause of gastrointestinal illness in humans and animals including domestic, wild, and in captivity animals, and more than 30 validated species of Cryptosporidium are recognized as infectious to different hosts such as mammals, birds, reptiles, amphibians, and fish. Therefore, numerous investigations have been conducted worldwide in order to shed light on the epidemiology of this parasite and to explore its potential reservoirs. Few surveys, targeting humans and animals have been carried out regarding the epidemiology of Cryptosporidium spp. in France and no data are available about the circulation of this parasite in French zoological gardens. Herein, we determined the prevalence of Cryptosporidium in animals housed in two French zoos. A total of 307 fecal samples belonging to 161 species were screened by nested PCR. Overall, Cryptosporidium DNA was detected in 1.9% of the 161 species and 1% of the total number of fecal samples tested. Additionally, three Cryptosporidium species were identified: C. galli, C. andersoni, and C. tyzzeri. To our knowledge, this is the first molecular study focused on Cryptosporidium infection in captivity animals in France. This study is of interest considering the exposure of a large number of humans and animals to this waterborne protozoan, found ubiquitously in the environment.