[Blastocystis spp.: Advances, controversies and future challenges]

High parasite prevalence driven by the human-animal-environment interface: a One Health study in an urban area in southern of Chile

Parasitic infections remain a global health concern, affecting human populations worldwide. However, comprehensive studies evaluating human, animal, and environmental interactions driven transmission of parasites are limited. We conducted a One Health study in an urban area of Valdivia, Chile. Human participants provided fecal and blood samples for parasitological and serological analysis. Environmental soil samples were collected from public parks, and fecal samples from owned and stray dogs were analyzed. Detection of intestinal parasites employed microscopy and molecular techniques, including next-generation sequencing (NGS), while anti-Toxocara canis antibodies in humans were assessed using ELISA. Socioeconomic surveys explored risk factors associated with parasitism. Parasite prevalence was 28% in humans, 26% in owned dogs, and 44% in environmental dog feces. Anti-T. canis IgG antibodies were present in 33% of humans. Soil contamination was identified in up to 30.5% of park samples, harboring zoonotic parasites such as Toxocara sp. and Trichuris vulpis, the same species identified in environmental dog feces. Zoonotic subtypes of Giardia duodenalis and Blastocystis sp. were detected in humans. Our findings highlight significant zoonotic and environmental transmission contributing to human parasitic infections in urban settings, underscoring the need for integrated public health interventions. This study demonstrates the importance of adopting an OneHealth approach in the study of parasitology. The complex ecology of parasites requires an integrated perspective to fully understand their transmission pathways and develop effective control strategies. By emphasizing the interconnectedness of human, animal, and environmental health, we aim to contribute to the management and mitigation of this persistent public health issue.

Differential gut microbiome in spondyloarthritis patients associated to Blastocystis colonization

The role of Blastocystis in intestinal health is an open controversy, and little is known about the potential effect of this microorganism in autoinflammatory diseases such as spondyloarthritis (SpA). Here, we analyzed the gut microbiome of 36 SpA patients and 13 control individuals and demonstrated that the richness, diversity, and taxonomic composition between these two groups are different. We also showed that colonization by Blastocystis in control individuals increases the richness and diversity of the intestinal microbiome, whereas in SpA patients, it does not seem to have any impact. This may reflect a potential role of Blastocystis in sculpting the gut microbiome architecture in control individuals, whereas in subjects with SpA, the modulation of the microbiome may be governed by disease-dependent factors that cannot be overcome by Blastocystis. Regarding taxonomic characterization, SpA patients colonized by Blastocystis showed significant increases in the phylum Pseudomonadota, class Gammaproteobacteria, family Succinivibrionaceae, and genus Succinivibrio. Simultaneously, there were significant increases in the class Bacilli, order Lactobacillales, families Lactobacillaceae and Clostridiaceae, and genera Lactobacillus and Clostridium in non-colonized SpA patients. On the other hand, PICRUSt analysis in Blastocystis-positive SpA patients showed elevations in pathways that may enhance antioxidant capacities and alleviate intestinal inflammation, while Blastocystis-negative SpA patients showed significant changes in pathways that promote cell division/proliferation and can lead to larger changes in the gut microbiome. Our analyses lead us to believe that these changes in the gut microbiome of SpA patients may trigger protective mechanisms as an initial response to inflammation in an attempt to restore balance in the intestinal environment.

Prevalence of intestinal parasites and molecular characterization of Giardia intestinalis, Blastocystis spp. and Entamoeba histolytica in the village of Fortín Mbororé (Puerto Iguazú, Misiones, Argentina)

Background

Intestinal parasites (IPs) are widely distributed worldwide and are one of the major contributors to gastrointestinal disease. Their prevalence is associated with poor access to water, sanitation and hygiene (WASH). The objective of this study was to identify the prevalence of IPs, including soil-transmitted helminths (STH), and their relation to socioeconomic characteristics, as well as a first approach to molecularly characterize the types of Giardia intestinalis, Blastocystis spp. and Entamoeba histolytica present in an indigenous community from Puerto Iguazú, Misiones, Argentina.

Methods

A cross-sectional study was conducted in the rural settlement of Fortin Mbororé between January and March 2018. Socioeconomic variables, household characteristics, and stool and blood samples were collected. Standard coprological techniques were used to analyze stool samples, and a complete hemogram was performed on the blood samples. Giardia intestinalis microscopy-positive samples were genetically typed by the β-giardin (bg) gene. Molecular identification of Blastocystis spp. subtypes and E. histolytica were carried out by amplification and sequencing of a partial fragment of the small subunit ribosomal RNA gene (SSU rDNA).

Results

The overall prevalence of IPs was 92.7%, with 72.0% specifically for hookworm. IPs were significantly more prevalent in preschool- and school-age children (P < 0.05). No formal education (P = 0.035), the presence of unimproved floors (P = 0.001) and overcrowding (P = 0.005) were significantly associated with IP infection. Hookworm was associated with anemia (P = 0.019). Molecular characterization revealed the presence of E. histolytica sub-assemblages AII (12.5%), AIII (87.5%) and BIV (100%); one case of sub-assemblage D for G. intestinalis; and the presence of subtypes ST1 (14.8%), ST2 (14.8%) and ST3 (70.4%) of Blastocystis spp.

Conclusions

Protozoans detected in this study are transmitted mainly through water contaminated with fecal matter, evidencing the need to improve the quality of water and sanitation for the inhabitants of Fortín Mbororé. Molecular characterization showed that domestic animals can be implicated in the zoonotic transmission of G. intestinalis and Blastocystis spp. to humans. A hyperendemic area for STH was found, with hookworm prevalence greater than 50%. Therefore, improvements in WASH as well as mass deworming programs need to be implemented in this area to control and decrease the prevalence of IPs in general and STH in particular.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04968-z.

Epidemiological and Molecular Characterization of Blastocystis Infection in Children Attending Daycare Centers in Medellín, Colombia

Simple Summary

Blastocystis infection affects more than 1000 million people globally. Its frequency varies depending on sociodemographic conditions, hygienic habits, provision of public services, and predisposing factors for contracting the infection, considering the child population as the most affected in developing countries. The lack of studies on this protozoan prevents the understanding of its transmission dynamics and its implications for the population’s health. For this protozoan, the diagnosis is based on microscopic reporting by conventional techniques; and subtype identification, which vary depending on the epidemiological distribution, host, and symptoms. In our study, we describe its epidemiological and molecular characterization in a child population. Additionally, we compare the diagnosis methods of Blastocystis; our research identified a better sensitivity with molecular methods and a great diversity of alleles and subtypes in this population.

Abstract

Background: The present study aims to perform an epidemiological and molecular characterization of Blastocystis infection in a child population attending daycare centers of Medellín, Colombia. Methods: A total of 265 children aged 0–5 years were enrolled in five children’s centers in urban sectors of Medellín, northwestern Colombia. Stool samples were taken to identify intestinal parasites by direct examination, Ritchie–Frick concentration, and molecular identification of Blastocystis by conventional PCR and subtype (ST) identification by PCR barcoding with subsequent phylogenetic reconstruction. Kappa index was calculated to evaluate the agreement between microscopy and PCR for the diagnosis of Blastocystis. Results: The prevalence of intestinal protozoa was 36.6% (97/265), with Blastocystis as the most frequent parasitic protozoan at 15.8% (42/265), followed by Giardia intestinalis at 15.5% (41/265) and Endolimax nana at 15.1% (40/265). The prevalence of Blastocystis by PCR was 53.2% (141/265), the subtypes identified were ST3 at 30.5% (18/59), ST2 at 23.7% (14/59), ST1 at 20.3% (12/59), and with less frequency, ST4 at 5.1% (3/59), ST6 at 1.7% (1/59) and ST16 at 15.3% (9/59) allele 162. Conclusion: This study provides the first genetic characterization of Blastocystis subtypes circulating in a population of Medellín, Colombia, and also updates the epidemiology of Blastocystis subtypes in the world with the first identification of ST16 in humans.

Relative Frequency of Blastocystis Subtypes 1, 2, and 3 in Urban and Periurban Human Populations of Arequipa, Peru

Blastocystis is one of the most common protozoa found in the human gut and are genetically diverse and widely distributed around the world. Nonspecific and inconsistent symptoms have been associated with this protozoon; thus, its clinical importance remains controversial. Our aim was to estimate the relative frequency of Blastocystis subtypes 1, 2, and 3, which are the predominant subtypes reported in South America, based on conserved regions of SSU rDNA sequences and determine the factors associated with them. A total of 116 Blastocystis-positive stool samples were processed using conventional PCR with Blastocystis-specific primers. We identified subtype 1 (10.3%), subtype 2 (7.8%), subtype 3 (25.0%), and mixed subtype infections (8.7%). However, we could not identify any Blastocystis subtypes in 48.3% of the samples; therefore, it is likely that other subtypes were present in the area. No association was found between any gastrointestinal symptom and single or mixed Blastocystis subtypes. We found a statistically significant association between Blastocystis subtype 2 and irritable bowel syndrome (OR = 17.8, 95% CI = 1.5-408.4, p = 0.039); however, the number of samples with IBS was small (n= 4). There was no association between the Blastocystis subtypes and any epidemiological variable studied. In rural populations, we only identified subtype 1, while in urban and periurban populations, we identified subtypes 1, 2, and 3.

Prevalence and subtype distribution of Blastocystis sp. infecting children from a rural community in Panama

Blastocystis sp. is a commonly reported intestinal parasite with a worldwide distribution. Phylogenetic analyses describe at least 17 subtypes for this parasite, and nine of them have been found in humans. However, the prevalence and some epidemiological characteristics of this parasitic infection in rural communities are not well known. The objective of this cross-sectional study was to evaluate the prevalence, subtypes, and epidemiological factors related to Blastocystis sp. Infection in children from of a small rural community in the central area of Panama. For this, 66 fecal samples from children (1 to 12 years old), were initially analyzed for the presence of parasites by a formalin-ethyl acetate/concentration method. Molecular detection and identification of Blastocystis sp. subtypes were carried out by amplification and sequencing of a partial fragment of the small-subunit ribosomal RNA gene. Using data from a questionnaire, analyses of epidemiological conditions potentially associated with Blastocystis sp. transmission were also conducted. Microscopic diagnostics showed that 33.3% (22/66) of the analyzed samples presented entero-parasites. Among them, Blastocystis sp. was the most prevalent, with 21.2% (14/66), followed by the E. histolytica/dispar/moshkovskii complex 4.5% (3/66), Giardia lamblia 1.5% (1/66) and Strongyloides stercoralis 1.5% (1/66). PCR-based analyses detected a prevalence of Blastocystis sp. infection of 74.2% (49/66) in apparently healthy children. Phylogenetic analysis revealed two different subtypes of this parasite: ST1 with 42.2% (28/66) infected, and ST3 with 31.8% (21/66) infected. In addition, recent diarrhea was significantly associated with Blastocystis sp. infection. None of the other risk factors evaluated was statistically associated with infection. These results highlight the need to further investigate clinical, epidemiological, and genetic characteristics of Blastocystis sp. infections in this community.

Molecular detection and genotyping of intestinal protozoa from different biogeographical regions of Colombia

Background

Intestinal parasitic protozoa represent a serious problem of public health particularly in developing countries. Protozoa such as Blastocystis, Giardia intestinalis, Entamoeba histolytica and Cryptosporidium spp. are associated with diarrheal symptoms. In Colombia, there is little region-specific data on the frequency and circulating genotypes/species of these microorganisms. Therefore, the main objective of our study was to employ molecular detection and genotyping of G. intestinalis and Blastocystis, Cryptosporidium and Entamoeba spp. in samples from different biogeographical regions of Colombia.

Methods

We collected 649 human fecal samples from five biogeographical regions of Colombia: the Amazon, Andean, Caribbean, Orinoco and Pacific regions. Blastocystis, G. intestinalis, Cryptosporidium spp. and Entamoeba complex were detected by microscopy and conventional PCR. Molecular genotyping was conducted to identify Blastocystis subtypes (STs) (18s), G. intestinalis assemblages (triose phosphate isomerase and glutamate dehydrogenase) and Cryptosporidium species (18s). Genetic diversity indices were determined using dnasp.5.

Results

We detected G. intestinalis in 45.4% (n = 280) of samples, Blastocystis in 54.5% (n = 336) of samples, Cryptosporidium spp. in 7.3% (n = 45) of samples, Entamoeba dispar in 1.5% (n = 9) of samples, and Entamoeba moshkovskii in 0.32% (n = 2) of samples. Blastocystis STs 1–4, 8 and 9 and G. intestinalis assemblages AII, BIII, BIV, D and G were identified. The following Cryptosporidium species were identified: C. hominis, C. parvum, C. bovis, C. andersoni, C. muris, C. ubiquitum and C. felis. The Caribbean region had the highest frequency for each of the microorganisms evaluated (91.9% for G. duodenalis, 97.3% for Blastocystis, 10.8% for Cryptosporidium spp., 13.5% for E. dispar and 2.7% for E. moshkovskii). The Orinoco region had a high frequency of Blastocystis (97.2%) and the Andean region had a high frequency of G. intestinalis (69.4%). High and active transmission was apparent in several regions of the country, implying that mechanisms for prevention and control of intestinal parasitosis in different parts of the country must be improved.

The first molecular detection of Blastocystis subtypes in human faecal samples from Ibague, Colombia

Blastocystis spp. has become one of the protozoans arousing the greatest scientific interest because of the controversy surrounding its biology; it is currently considered one of the most prevalent organisms in humans and animals worldwide. Such prevalence increases, especially in tropical countries where infection rates are high, highlighting the need to conduct studies focused on understanding this protozoan's biology. Interestingly, molecular tools are emerging as the best option for diagnosing this infection. This study was thus aimed at conventional PCR molecular detection and characterisation of Blastocystis spp. in human faecal samples from Ibagué, Colombia, using primers targeting the small subunit ribosomal ribonucleic acid (rRNA) gene. One hundred human faecal samples with confirmed Blastocystis spp. were studied, revealing the following subtype genetic diversity: ST1 50%, ST2 33% and ST3 17%. The results contributed to the limited information available regarding Blastocystis spp. in Colombia and created a reference point for further studies in the region.

Risk factors for intestinal parasitoses among children and youth of Buenos Aires, Argentina

Introduction

Intestinal parasitoses affect millions of people worldwide, especially children of developing countries. In Argentina, the prevalence of these infections varies among areas according to socio-economic and climatic variability. This study aimed to evaluate the prevalence of intestinal parasitoses and risk factors in child and youth populations from neighbourhoods of La Plata (Buenos Aires province, Argentina) affected by occasional floods, including a serious flood in 2013.

Methods

Serial stool samples and anal swabs of 398 individuals were processed using techniques of sedimentation and flotation. Socio-economic variables were surveyed using a semi-structured questionnaire and the land use/cover was determined by classification of a satellite image.

Results

Of all examined individuals, 70.9% were parasitized by at least one of the 12 parasites identified. The most prevalent species were Blastocystis sp. (42.7%), Enterobius vermicularis (34.7%) and Giardia lamblia (17.6%). Infection risk factors included houses built with makeshift materials and dirt floors; lack of piped water and public waste collection service, bed-sharing and living in the non-urban area. >70.3% of the participants that lived within <200 m from watercourses or permanent water bodies were parasitized.

Conclusion

This research shows that parasitic infections are still a serious public health problem and that they are strongly associated with socio-economic conditions and land use/cover. In this context, studies focused on One Health strategy are need to ensure the diagnosis and surveillance of parasitosis and to tackle zoonotic diseases as well as to encourage the development of sanitary and educational programs sustainable over time.

A summary of Blastocystis subtypes in North and South America

Background

Blastocystis is a stramenopile of worldwide significance due to its capacity to colonize several hosts. Based on its high level of genetic diversity, Blastocystis is classified into global ribosomal subtypes (STs). The aim of this study was to conduct a summary of Blastocystis STs and depict their distribution throughout North and South America; we did this by assembling maps and identifying its most common 18S alleles based on diverse studies that had been reported all over the continent and whose Blastocystis-positive samples were obtained from numerous hosts.

Results

Thirty-nine articles relating to nine countries from the American continent were considered, revealing that ST1 (33.3%), ST2 (21.9%), ST3 (37.9%), ST4 (1.7%), ST5 (0.4%), ST6 (1.2%), ST7 (1%), ST8 (0.7%), ST9 (0.4%), ST12 (0.3%), Novel ST (1.1%) and Mixed STs (0.2%) occurred in humans. The STs in other animal hosts were ST1 (6.5%), ST2 (6.5%), ST3 (4.7%), ST4 (7.2%), ST5 (15.9%), ST6 (17.3%), ST7 (3.6%), ST8 (20.6%), ST10 (9%), ST14 (3.6%), ST17 (1.1%) and Novel ST (4%). The countries that presented the most abundant variety of studies reporting STs were the USA with 14 STs, Brazil with 9 STs and Colombia with 8 STs. Additionally, new variants had been described in the last few years, which have increased the prevalence of these subtypes in the countries studied, such as Novel ST (1.1%) and Mixed STs (0.2%) in humans and Novel ST (4%) in animals.

Conclusions

This summary updates the epidemiological situation on the distribution of Blastocystis STs in North and South America and will augment current knowledge on the prevalence and genetic diversity of this protozoan.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3641-2) contains supplementary material, which is available to authorized users.