Prevalence of Blastocystis hominis and Strongyloides stercoralis infection in Okinawa, Japan

Lipid Accumulation in Blastocystis Increases Cell Damage in Co-Cultured Cells

Blastocystis hominis is an intestinal protozoan that is often neglected, despite causing abdominal pain and diarrhea. Previous research has demonstrated that lipids can be synthesized by B. hominis or can accumulate in growth medium, but their function and mechanisms in the pathogenesis of Blastocystis remain unclear. Our study found that lipid-rich Blastocystis ST7-B can increase inflammation and disrupt Caco-2 cells more than the same parasite without the lipovenoes supplement. Additionally, the cysteine protease of Blastocystis, a virulence factor, is upregulated and has higher activity in lipid-rich Blastocystis. In order to better understand the effects of lipids on Blastocystis pathogenesis, we treated lipid-lowering pravastatin during Blastocystis ST7-B culturing with a lipovenoes supplement, which decreased the lipid levels of the Blastocystis and reduced the Blastocystis-induced inflammation and cell disruption of Caco-2 cells. We also analyzed the fatty acid composition and possible synthesis pathway in Blastocystis ST7-B, finding significantly higher ratios of arachidonic acid, oleic acid, and palmitic acid than in the other lipid components in lipid-rich Blastocystis ST7-B. These results suggest that lipids play a significant role in the pathogenesis of Blastocystis and provide important information on the molecular mechanisms of and potential treatments for Blastocystis infection.

Prevalence and Subtype Distribution of Blastocystis in Tibetan Sheep in Qinghai Province, Northwestern China

Blastocystis is one of the most common intestinal protists in humans and a great number of animals, including sheep and goats. High prevalence and multiple subtypes of Blastocystis have been reported in sheep in several regions of China and elsewhere. However, there is a dearth of knowledge about Blastocystis in Tibetan sheep. A total of 761 fecal samples were collected from Tibetan sheep in seven counties of Qinghai Province, northwestern China, and were examined for the prevalence and subtypes of Blastocystis using molecular technology based on the partial small subunit ribosomal RNA gene of Blastocystis. The overall prevalence of Blastocystis in the investigated Tibetan sheep was 7.5% (57/761) using PCR and DNA Sanger sequencing, and differences in prevalence were observed among the ruminants from the seven counties (P < 0.01), and across four seasons (P < 0.01). Sequence analysis revealed five subtypes (ST14 (57.9%), ST10 (26.3%), ST12 (5.3%), ST21 (5.3%), and ST30 (5.3%)) of Blastocystis sp. in these Tibetan sheep, with ST14 as the predominant subtype. To our knowledge, this is the first report of Blastocystis colonization in Tibetan sheep.

Neglected gut microbiome: interactions of the non-bacterial gut microbiota with enteric pathogens

A diverse array of commensal microorganisms inhabits the human intestinal tract. The most abundant and most studied members of this microbial community are undoubtedly bacteria. Their important role in gut physiology, defense against pathogens, and immune system education has been well documented over the last decades. However, the gut microbiome is not restricted to bacteria. It encompasses the entire breadth of microbial life: viruses, archaea, fungi, protists, and parasitic worms can also be found in the gut. While less studied than bacteria, their divergent but important roles during health and disease have become increasingly more appreciated. This review focuses on these understudied members of the gut microbiome. We will detail the composition and development of these microbial communities and will specifically highlight their functional interactions with enteric pathogens, such as species of the family Enterobacteriaceae. The interactions can be direct through physical interactions, or indirect through secreted metabolites or modulation of the immune response. We will present general concepts and specific examples of how non-bacterial gut communities modulate bacterial pathogenesis and present an outlook for future gut microbiome research that includes these communities.

Prevalence and Subtype Distribution of Blastocystis Isolated from School-Aged Children in the Thai-Myanmar Border, Ratchaburi Province, Thailand

Blastocystis is one of the most common enteric protozoa that inhabits the intestinal tract of humans and different animals. Moreover, it has a worldwide geographic distribution. Its main mode of transmission is via the fecal-oral route. At present, 26 subtypes are widely distributed across both humans and animals. The current study aimed to determine the prevalence and subtype distribution of Blastocystis among school-aged children living on the Thai-Myanmar border, Ratchaburi province, Thailand. In total, 508 samples were collected from children at six schools. The prevalence of Blastocystis infection was amplified and sequenced in the 600 bp barcode region of the small-subunit ribosomal RNA (SSU rRNA). The overall prevalence of Blastocystis infection was 3.35% (17/508). ST3 (11/17) was the most predominant subtype, followed by ST1 (5/17) and ST2 (1/17). A phylogenetic tree was constructed based on the Tamura92+G+I model using the maximum-likelihood algorithm. Surprisingly, all sequences of the ST3-positive samples were closely correlated with the cattle-derived sequence. Meanwhile, all sequences of the Blastocystis ST1-positive samples were closely correlated with the human-derived sequence. Nevertheless, further studies should be conducted to validate the zoonotic transmission of Blastocystis. Based on our findings, personal hygiene and sanitation should be improved to promote better health in children in this area.

Evaluation of two analytical methods of detection for intestinal parasites in curly lettuce sold in food stalls

Abstract This study aimed to investigate the occurrence of parasitic structures in curly lettuce (Lactuca sativa L.) sold in food stalls open markets in Cuiabá city, in the Brazilian state of Mato Grosso (MT). For this purpose, 50 samples were evaluated using spontaneous sedimentation and centrifugal flotation methods. These techniques showed positivity in 96% (48/50) and 78% (39/50) of the samples, respectively. The sedimentation method was statistically (p ≤ 0.05) more effective in detecting parasitic structures of the pathogens as Entamoeba histolytica, Ascaris spp., Strongyloides spp., Larvae and Hookworm eggs, when comparing both methods. However, these methods did not differ significantly for the detection of Giardia lamblia. Ascaris spp and Entamoeba coli occurred in 64% (32/50) and 46% (23/50) of the positive samples, respectively, with the highest percentages observed. The occurrence of Blastocystis spp., Fasciola spp., Dipylidium caninum and Ascaris lumbricoides revealed detection exclusively by the spontaneous sedimentation method, while Iodamoeba butschlii and Enterobius vermicularis were detected by centrifugal– flotation procedure. These results could reinforce the need to use methods based on sedimentation and the fluctuation of parasite structures in the analysis of lettuce. The presence of parasites in lettuce by fecal origin, with recognized pathogenicity, represents a risk to consumer health and demonstrates a deficit in good agricultural practices in the production, distribution and commercialization of lettuce.

Epidemiology and subtype distribution of Blastocystis in humans: A review

Blastocystis is a commonly encountered gastrointestinal protozoan in humans and animals with uncertain pathogenicity. Despite its potential public health impact, epidemiological data regarding the prevalence and molecular subtype (ST) distribution of Blastocystis have been rarely reported. Among Blastocystis STs, ST1-ST4 are common in humans, including healthy and immunodeficient populations. According to the Chi-squared (χ²) association based on the data compiled for this cross-sectional study, the presence of ST1 is associated with asymptomatic infection, whereas the presence of ST4 is associated with symptomatic infection. However, cross-sectional studies cannot clarify the potential pathogenicity of Blastocystis, unlike in vivo and in vitro studies. Poor hygiene, poor sanitation and zoonotic transmission are possible factors associated with high Blastocystis prevalence, although this protozoan may be part of the normal healthy human gastrointestinal microbiota. This review covers the prevalence, STs and distribution of Blastocystis infection in humans. Thus, future epidemiological and subtyping studies could reveal new STs in humans as well as possible associations of STs with disease, drug resistance and related mechanisms such as protease activity. These associations with proper ST identification may facilitate the control of potential threats to host health, including the direct pathogenic effects of Blastocystis or alterations of the gastrointestinal microbiome.

Genotypes of Blastocystis sp. among elderly health checkup people in South Korea with a questionnaire on risk factors

Blastocystis sp. is a common zoonotic intestinal parasite of humans and animals, and has been classified into at least 17 distinct subtypes. Despite its potential impact on public health, the prevalence and subtype distribution of Blastocystis sp. have seldom been the study subject in South Korea. To determine the prevalence and subtype distribution of Blastocystis sp. and to obtain information on risk factors, we performed a cross-sectional study targeting elderly health checkup people, who visited Seoul Western Branch of the Korea Association of Health Promotion (KAHP) in October 2019. Stool samples were collected from 293 participants consisting of 128 males and 165 females with a mean age of 64.7 years (from 50 to 88 years) with a questionnaire on potential risk factors. All the samples were tested by PCR targeting the SSU rRNA gene of Blastocystis sp., and nucleotide sequences of positive samples were used to identify the subtypes. The overall prevalence of Blastocystis sp. was 9.2% (27/293). Among the positive samples, subtype 3 was predominant (59%; 16/27), followed by subtype 1 (41%; 11/27). No other subtypes were detected. In the univariable analysis, the age, sex, presence of digestive symptoms, source of drinking water, and history of drug intake were not significantly associated with Blastocystis sp. infection. Two parameters, including the Enterococcus hirae bacterial infection and the frequency of intake of cooked or boiled vegetables less than twice a week, showed statistical significance. However, the multivariable regression analysis revealed that only the latter parameter was statistically significant. The results suggested that subtypes 3 and 1 are the 2 major genotypes of Blastocystis sp. among elderly people in South Korea, and low frequency of consuming cooked or boiled vegetables is a potential risk factor.

Prevalence and Subtype Distribution of Blastocystis Infection in Patients with Diabetes Mellitus in Thailand

Diabetes mellitus (DM) is a major global public health problem with an increasing prevalence. DM increases the risk of infections caused by bacteria, fungi, viruses, and parasites. We examined the prevalence, subtypes, and risk factors of Blastocystis infection in patients with and without DM in central Thailand. Stool samples and questionnaires were obtained from 130 people in the DM group and 100 people in the non-DM group. Blastocystis infection was identified via a nested polymerase chain reaction and subtyped via sequencing of the partial small-subunit ribosomal RNA (SSU rRNA) gene. Analysis of potential risk factors was conducted via binary logistic regression. The overall prevalence of Blastocystis infection was 10.8%, including rates of 9% and 12.3% in the non-DM and DM groups, respectively. The most prevalent subtype was ST3, followed by ST1, and ST4. Factors that potentially increased the risk of Blastocystis infection include patients being >65 years old, the presence of DM, a DM duration of ≥10 years, a low level of education, and animal ownership. In conclusion, this is the first study of Blastocystis infection in DM, and a high prevalence was found among this population. Therefore, health education promoting sanitation and hygiene is necessary to reduce and prevent infection in the community.

First detection of Blastocystis sp. in pigs in Slovakia and in Europe

Blastocystis sp. is a single-cell microorganism occurring in the gastrointestinal tract of humans and various animals and is distributed worldwide. Blastocystis exhibits extensive genetic diversity of 28 subtypes (STs) based on the small subunit ribosomal RNA (SSU rRNA) gene. In this study, the genetic diversity and zoonotic potential of Blastocystis were evaluated using pig faecal samples from two farms in Slovakia. Blastocystis spp. were detected in pigs intended for distribution and consumption. ST 5 subtype was identified in all positive samples and age categories with a prevalence of 12%. However, the prevalence on one of the farms was up to 28.6%. This is the first study of Blastocystis in pigs carried out in Slovakia. Although a number of samples obtained was small, the identified subtype of ST5 Blastocystis sp. occurs in humans and animals. It may have zoonotic potential and therefore may be a risk factor due to the close contact between humans and pigs on the breeding farms.

Status of Strongyloidiasis in Japan, 2000-2017

We reported 865 cases of soil-transmitted nematodiasis occurring in Japan during 2000-2017. The predominant nematode was Strongyloides stercoralis (n = 279, 32.3% of all cases), and other species included Ascaris lumbricoides (30.7%), Trichuris trichiura (23.1%), and Ancylostomidae spp. (13.9%). Strongyloides stercoralis was detected primarily in patients in Okinawa and Kagoshima prefectures, which are in the south of Japan and are endemic areas for this parasitic infection, and also in about half of the prefectures of all Japan. At least 15.5 cases of strongyloidiasis occurred on average each year. The period incidence rate of strongyloidiasis cases relative to the total population of Japan was 0.012 cases per 10⁵ person-years. The male-to-female ratio was 2.1. The average age was 75.1 ± 16.9 years, and 96.1% of patients were older than 50 years. Several reasons may explain why this previously non-endemic outside of Okinawa region, serious nematode disease is now found in much of Japan, including the increased number of transmigration and sightseeing trips in Japan, use of immunosuppressive drugs, and lack of awareness of the risks. Thus, information of strongyloidiasis and its risks must be disseminated to travelers, residents, and physicians to prevent this life-threatening parasite infection.

Blastocystis in Swiss children: a practical approach

Blastocystis is a parasite with a worldwide distribution and a varying prevalence in different countries. The pleomorphic nature of the protozoon and the lack of understanding a possible pathogenesis have led to confusion regarding its clinical significance. The aim of the study was to shed light on clinical characteristics of pediatric patients in Swiss children with a positive stool sample for Blastocystis, in order to provide recommendations for a practical approach for the clinician to know whom, when, and how to test. This is a retrospective study of pediatric patients, whose stool has been tested positive for Blastocystis in the last 10 years in northern Switzerland. A total of 4047 stool samples, belonging to 1887 different patients, were analyzed; 240 stool samples (of 160 patients) were tested positive for Blastocystis. On average, 2.2 (CI 1.98-2.35) stool samples per patient were analyzed, of which 1.48 (CI 1.36-1.61) were positive for Blastocystis. In 63% abdominal pain was the leading symptom, while in 17.5% it was an accidental finding without symptoms. There was a high significance in correlation of abdominal pain and chronicity (p < 0.0001) but none in diarrhea (p = 0.082) nor nausea/vomiting or other symptoms and chronicity. Followed by Entamoeba coli (8%), 26.3% of the patients with Blastocystis had a co-infection with another parasite, mostly Endolimax nana (13%).Conclusion: Carriage of Blastocystis is common; therefore, only children/teenagers at risk for a symptomatic Blastocystis infection should be tested. There is a good correlation between Blastocystis and chronic abdominal pain. Children with abdominal symptoms persisting over 4 weeks should have two different stool samples analyzed. No screening after travels/immigration is recommended.What is Known:• Blastocystis has a worldwide distribution.• The clinical significance is unclear.What is New:• Based on retrospective data, we recommend to only test children/teenagers with chronic abdominal pain for Blastocystis.• Two different stool samples should be examined by microscopy; serological investigations are not warranted.

Prevalence and Molecular Subtyping of Blastocystis from Patients with Irritable Bowel Syndrome, Inflammatory Bowel Disease and Chronic Urticaria in Iran

BACKGROUND

Blastocystis is a parasite that colonizes in the human intestine. Its clinical features include diarrhea, abdominal pain, or urticarial and irritable bowel syndrome (IBS). Spite of being significant genetic diversity and numerous subtypes within the genus there were no associations between its subtypes and symptomatology.

MATERIALS AND METHODS

Aim of this project was subtyping of the protozoa in 184 Iranian people with history of IBS/IBD (n = 74) or chronic urticaria (n = 59) and individuals referred to general clinic (n = 51). Microscopic and molecular examinations used for identifying and subtyping of Blastocystis.

RESULTS

Overall, frequency of the parasite was 24.46% while, 29.41% of people who referred to general clinic, 20.27%, and 25.42% of IBS/IBD and urticarial cases were infected, respectively. Subtyping result showed that 28.89% of all people were infected with Blastocystis sp. while the prevalence of ST3, ST2 and ST1 were 22.22%, 22.22%, and 17.78%, respectively. Blastocystis sp., was identified in most IBS/IBD cases (46.7%) followed with ST2 and ST3 (13.3 and 13.3, respectively). Whereas, in chronic urticaria group ST2(33.3%) was the major subtype and most individuals in control group were infected with ST3 (33.3%). Pearson's Chi Square test showed no significant differences between the parasite or subtype prevalence and diseases (p > 0.05).

CONCLUSION

Given significant factors have effect on clinical signs including host or parasite genetics, microbiota, as well as environmental factors, it seems that further studies are needed to find out different markers of host susceptibility to diverse parasite genotypes in patients with irritable bowel syndrome or urticaria.

Geospatial analysis and epidemiological aspects of human infections with Blastocystis hominis in Mazandaran Province, northern Iran

OBJECTIVES

Blastocystis hominis is a very common large intestinal protozoan with global prevalence in humans and non-human hosts. No precise statistics exist regarding the geographical distribution of Blastocystis that would enable the identification of high-risk communities. Therefore, the current research aimed to characterize the spatial patterns and demographic factors associated with B. hominis occurrence in northern Iran.

METHODS

The current study was performed among 4,788 individuals referred to health centers in Mazandaran Province, from whom stool samples were obtained. Socio-demographic data were gathered using a questionnaire. Samples were examined by a direct wet mount, the formalin-ethyl acetate concentration technique, and trichrome staining. Moran local indicators of spatial association and a geographically weighted regression model were utilized to analyze the results.

RESULTS

Generally, the infection rate of Blastocystis parasites was 5.2%, and was considerably higher in the age group of 10-14 years (10.6%) than in other age groups (p=0.005). Our data showed important associations between the occurrence of B. hominis and age, residence, job, contact with domestic animals, anti-parasitic drug consumption, and elevation above sea level (p<0.001).

CONCLUSIONS

The current study characterized for the first time the infection rate and risk of B. hominis in the north of Iran, and produced a prediction map. It is expected that this map will help policymakers to plan and implement preventive measures in high-risk areas and to manage already-infected patients.

A Simple Genotyping Method for Rapid Differentiation of Blastocystis Subtypes and Subtype Distribution of Blastocystis spp. in Thailand

Blastocystis spp. is one of the most common protozoa of humans and animals worldwide. The genetic diversity of Blastocystis spp. might be associated with a wide range of symptoms. However, the prevalence of each subtype is different in each country. Until now, there is no standard method for subtyping of Blastocystis spp. We developed a sequential restriction fragment length polymorphism (RFLP) analysis for the rapid differentiation of human Blastocystis subtypes. A large-scale study was also conducted to determine the subtype distribution of Blastocystis spp. in Thailand. Stool samples were collected from 1025 school-age students in four regions of Thailand. Blastocystis infections were identified by direct smear, formalin ethyl-acetate concentration technique (FECT), Boeck and Drbohlav’s Locke-Egg-Serum (LES) medium culture, and polymerase chain reaction (PCR) of small-subunit ribosomal DNA (SSU rDNA). Subtypes of Blastocystis spp. were determined by RFLP. Phylogenetic tree of partial SSU rDNA sequences of Blastocystis spp. was constructed using the Maximum Likelihood (ML) method. Out of 1025 students, 416 (40.6%) were positive for Blastocystis spp. Using two steps of RFLP reactions, we could determine subtype one–three among these students. Subtype 3 was the most common subtype (58.72%) in Thai students, followed by subtype 1 (31.2%), and subtype 2 (10.1%). Blastocystis subtype 3 was the most prevalent in all regions of Thailand. The subtype distribution of Blastocystis spp. in Thailand was different from other countries.

Evaluation of two prognostic indices for adult T-cell leukemia/lymphoma in the subtropical endemic area, Okinawa, Japan

Aggressive adult T-cell leukemia/lymphoma (ATL) has an extremely poor prognosis and is hyperendemic in Okinawa, Japan. This study evaluated two prognostic indices (PIs) for aggressive ATL, the ATL-PI and Japan Clinical Oncology Group (JCOG)-PI, in a cohort from Okinawa. The PIs were originally developed using two different Japanese cohorts that included few patients from Okinawa. The endpoint was overall survival (OS). Multivariable Cox regression analyses in the cohort of 433 patients revealed that all seven factors for calculating each PI were statistically significant prognostic predictors. Three-year OS rates for ATL-PI were 35.9% (low-risk, n = 66), 10.4% (intermediate-risk, n = 256), and 1.6% (high-risk, n = 111), and those for JCOG-PI were 22.4% (moderate-risk, n = 176) and 5.3% (high-risk, n = 257). The JCOG-PI moderate-risk group included both the ATL-PI low- and intermediate-risk groups. ATL-PI more clearly identified the low-risk patient subgroup than JCOG-PI. To evaluate the external validity of the two PIs, we also assessed prognostic discriminability among 159 patients who loosely met the eligibility criteria of a previous clinical trial. Three-year OS rates for ATL-PI were 34.5% (low-risk, n = 42), 9.2% (intermediate-risk, n = 109), and 12.5% (high-risk, n = 8). Those for JCOG-PI were 22.4% (moderate-risk, n = 95) and 7.6% (high-risk, n = 64). The low-risk ATL-PI group had a better prognosis than the JCOG-PI moderate-risk group, suggesting that ATL-PI would be more useful than JCOG-PI for establishing and examining novel treatment strategies for ATL patients with a better prognosis. In addition, strongyloidiasis, previously suggested to be associated with ATL-related deaths in Okinawa, was not a prognostic factor in this study.

Molecular identification of Blastocystis sp. subtypes in water samples collected from Black sea, Turkey

The aim of this study was to identify the subtypes of Blastocystis sp. and complete a phylogenetic analysis of 268 water samples that were collected from the Samsun, Amasya and Sinop Provinces of the Black Sea in Turkey, between the years 2011 and 2014. Blastocystis sp. was investigated in 48 uncultured sea water samples that were collected from 4 sites within the Sinop Province. A total of 100 river water samples were collected from 37 sites in the Samsun Province and 120 river water samples were collected from 10 sampling sites within the Amasya Province. The small subunit (SSU) rDNA gene Polymerase chain reaction (PCR) were performed for the detection of Blastocytis sp. and the PCR-positive samples were sequenced. Subsequently, the (SSU) rDNA sequences were aligned by Bioedit and phylogenetic trees were constructed for Blastocystis with reference to the genotypes from GenBank. Blastocystis sp. were found in 3 out of the 75 (4%) river water samples that were collected from the Samsun Province. Six of the 120 (5%) river water samples and 1 out of the 48 (2%) seawater samples were positive for Blastocystis in the Amasya and Sinop Provinces. There were two different subtypes (ST; 1 and 3) found from sequencing all of the samples from the investigated sites. Two and one PCR products were found to be positive for ST1 and ST3 from the different samples collected within the Samsun Province. Two and 4 PCR products from the Amasya Province were ST1 and ST3, respectively and only one sample from the Sinop Province was found to be positive for ST1. This is the first report to identify and report the occurrence of Blastocystis subtypes within the Black Sea of Turkey.

Prevalence and staining characteristics of Blastocystis isolates from food animals in Tamil Nadu

The present study was undertaken to investigate the prevalence and staining characteristics of Blastocystis isolated from food animals. Smears of the duodenal and caecal mucosal scrapings, collected from food animals, were stained with Giemsa, Gram's, modified acid-fast and acridine orange. Blastocystis was identified in 295 samples, including faeces and intestinal contents of animals like small ruminants (95), poultry (170) and pigs (30). The prevalence in pigs was found to be high (94.4%) followed by poultry (29.4%) and small ruminants (14%). Various forms of Blastocystis such as vacuolar, granular and amoeboid forms were identified by using different stains. The parasites stained with Giemsa were identified by the presence of eosinophilic nucleus and basophilic cytoplasm. In organisms stained with Gram's stain, the cytoplasm of the vacuolar forms took up the counter stain safranine. Blastocystis appeared as a pink colored cyst against bluish green background with modified acid-fast staining. The study shows that there is a very high prevalence of Blastocystis among the food animals investigated. Simple parasitological procedures, including direct microscopical examination and staining with agents like Giemsa, Gram's and acridine orange can assist identification of the parasites from intestinal contents and faecal material.

Prevalence and risk factors of Blastocystis infection among underprivileged communities in rural Malaysia

OBJECTIVES

To determine the prevalence and risk factors of Blastocystis among underprivileged communities living in rural Malaysia.

METHODS

This cross-sectional study was conducted among 253 participants aged between 1 and 85 years. Stool samples were examined using Wheatley's trichrome stain after in-vitro cultivation in Jones' medium to detect the presence of Blastocystis. Information pertaining to the demography, socioeconomic and environment were collected using pre-validated questionnaires.

RESULTS

The total prevalence of Blastocystis infection was 40.7%. The multiple logistic regression analysis revealed that age ≥15 years (OR = 2.72; 95% CI = 1.47-5.04) and presence of infected family members (OR = 8.56; 95% CI = 4.47-16.38) were the significant risk factors associated with blastocystosis in these communities.

CONCLUSIONS

Blastocystosis is revealed through this study to be still prevalent among Orang Asli communities in rural Malaysia. The two main approaches that should be implemented by the public health authority in battling this infection would be the screening of other family members and giving treatment to the infected individuals. Moreover, it is imperative for health education on good personal and food hygiene practices are provided in order to reduce the morbidity and transmission of Blastocystis infection among the Orang Asli in their communities meaningfully.

Subtype Distribution of Blastocystis in Communities along the Chao Phraya River, Thailand

Blastocystis is a common zoonotic enteric protozoan that has been classified into 17 distinct subtypes (STs). A cross-sectional study was conducted to determine the prevalence and subtype distributions of Blastocystis in villagers living along the Chao Phraya River, Ayutthaya Province, Thailand, and to assess the risk of zoonotic infection. In total, 220 stool samples were collected, and DNA was extracted. PCR and sequencing were performed with primers targeting the small-subunit ribosomal RNA (SSU rRNA) genes. Blastocystis was present in 5.9% (13/220) of samples, and ST3 (5.0%; 11/220) was the predominant subtype, followed by ST2 (0.45%; 1/220) and ST6 (0.45%; 1/220). Phylogenetic trees were constructed with the maximum-likelihood method based on the Hasegawa–Kishino–Yano + G + I model, neighbor-joining, and maximum parsimony methods. The percentage of bootstrapped trees in which the associated taxa clustered together was relatively high. All the sequences of the Blastocystis-positive samples (KU051524–KU051536) were closely related to those from animals (pig, cattle, and chicken), indicating a zoonotic risk. Therefore, the villagers require proper health education, especially regarding the prevention of parasitic infection, to improve their personal hygiene and community health. Further studies are required to investigate the Blastocystis STs in the animals living in these villages.

Strongyloidiasis: A Disease of Socioeconomic Disadvantage

Strongyloidiasis is a disease caused by soil transmitted helminths of the Strongyloides genus. Currently, it is predominately described as a neglected tropical disease. However, this description is misleading as it focuses on the geographical location of the disease and not the primary consideration, which is the socioeconomic conditions and poor infrastructure found within endemic regions. This classification may result in misdiagnosis and mistreatment by physicians, but more importantly, it influences how the disease is fundamentally viewed. Strongyloidiasis must be first and foremost considered as a disease of disadvantage, to ensure the correct strategies and control measures are used to prevent infection. Changing how strongyloidiasis is perceived from a geographic and clinical issue to an environmental health issue represents the first step in identifying appropriate long term control measures. This includes emphasis on environmental health controls, such as better infrastructure, sanitation and living conditions. This review explores the global prevalence of strongyloidiasis in relation to its presence in subtropical, tropical and temperate climate zones with mild and cold winters, but also explores the corresponding socioeconomic conditions of these regions. The evidence shows that strongyloidiasis is primarily determined by the socioeconomic status of the communities rather than geographic or climatic conditions. It demonstrates that strongyloidiasis should no longer be referred to as a "tropical" disease but rather a disease of disadvantage. This philosophical shift will promote the development of correct control strategies for preventing this disease of disadvantage.

Strongyloidiasis in a young French woman raises concern about possible ongoing autochthonous transmission in Spain

Strongyloidiasis is one of the most common geohelminth infections in tropical and subtropical areas. Accurate diagnosis remains challenging, leading to an overall underestimation of strongyloidiasis prevalence. The possibility of ongoing autochthonous transmission in some temperate areas and especially in southern Europe is still debated, and data supporting this hypothesis are scarce. The case of a young French woman, who had travelled frequently to Spain and had acquired Strongyloides stercoralis infection as revealed by gastrointestinal symptoms and hypereosinophilia, is reported here. Physicians should keep in mind the risk of being infected in some areas of southern Europe, even if low, in order to avoid the life-threatening manifestations of strongyloidiasis favoured by pathological or therapeutic immunosuppression.

The distribution of Blastocystis subtypes in isolates from Qatar

Background

Blastocystis is a common single-celled intestinal parasite of humans and other animals comprising at least 17 genetically distinct small subunit ribosomal RNA lineages (subtypes (STs)), nine of which have been found in humans. The geographic distribution of Blastocystis subtypes is variable, but the subtypes present in Qatar are at present unknown.

Methods

Stool samples were collected from randomly selected, apparently healthy subjects arriving in Qatar for the first time. Blastocystis subtypes were determined by sequencing of the small subunit rRNA gene (SSU rDNA) PCR products. Phylogenetic analyses were done using Maximum Composite Likelihood method.

Results

71.1 % of samples were positive for Blastocystis infection based on PCR-detection methodology compared to only 6.9 % by microscopy. Prevalence of Blastocystis did not differ between the sexes nor between age classes. However, there was a regional difference in prevalence with subjects arriving from Africa showing the highest (87.6 %), those from Western Asia intermediate (68.6 %) and from Eastern Asia the lowest prevalence (67.6 %). Genetic analysis detected only three STs. ST3 was the most common (69.3 %) and ST2 was the rarest (3.5 %), while ST1 had a prevalence of 27.2 %. ST2 showed a regional variation, being absent from the 64 Western Asian Blastocystis-positive subjects. Both ST1 and ST3 showed significant differences in prevalence between the sexes.

Conclusions

This is the first report exploring the distribution of Blastocystis subtypes in our region. We recommend that stool screening via microscopy for the presence of Blastocystis should be abandoned since it is extremely insensitive. In future, the prevalence of Blastocystis infections should be based on PCR methodology and we predict that in the years ahead diagnostic PCR will become the tool of choice. More work is needed to identify the full range of Blastocystis subtypes that circulate in our region.

Subtype distribution of Blastocystis in Thai-Myanmar border, Thailand

Blastocystis sp. is a common zoonotic intestinal protozoa which has been classified into 17 subtypes (STs). A cross-sectional study was conducted to determine the prevalence and subtype distribution of Blastocystis in villagers living on the Thai-Myanmar border, where the risk of parasitic infection is high. A total of 207 stool samples were collected and DNA was extracted. PCR and sequencing using primers targeting small-subunit ribosomal RNA (SSU rRNA) gene were performed. The prevalence of Blastocystis infection was 37.2% (77/207). ST3 (19.8%; 41/207) was the predominant subtype, followed by ST1 (11.6%; 24/207), ST2 (5.3%; 11/207), and ST4 (0.5%; 1/207). A phylogenetic tree was reconstructed using the maximum likelihood (ML) method based on the Hasegawa-Kishino-Yano + G + I model. The percentage of bootstrapped trees in which the associated taxa clustered together was relatively high. Some sequences of Blastocystis positive samples (TK18, 39, 46, 71, and 90) were closely related to animals (pig and cattle) indicating zoonotic risks. Therefore, proper health education in parasitic prevention for the villagers should be promoted to improve their personal hygiene. Further longitudinal studies are required to monitor the prevalence of parasitic infections after providing health education and to investigate Blastocystis ST in animals living in these villages.

Blastocystis, an unrecognized parasite: an overview of pathogenesis and diagnosis

Blastocystis sp. is among the few enteric parasites with a prevalence that often exceeds 5% in the general population of industrialized countries and can reach 30-60% in developing countries. This parasite is frequently found in people who are immunocompromised (patients with human immunodeficiency virus/acquired immunodeficiency syndrome or cancer) and a higher risk of Blastocystis sp. infection has been found in people with close animal contact. Such prevalence in the human population and the zoonotic potential naturally raise questions about the impact of these parasites on public health and has increased interest in this area. Recent in vitro and in vivo studies have shed new light on the pathogenic power of this parasite, suggesting that Blastocystis sp. infection is associated with a variety of gastrointestinal disorders, may play a significant role in irritable bowel syndrome, and may be linked with cutaneous lesions (urticaria). Despite recent significant advances in the knowledge of the extensive genetic diversity of this species, the identification of extracellular proteases as virulence factors and the publication of one isolate genome, many aspects of the biology of Blastocystis sp. remain poorly investigated. In this review, we investigate several biological aspects of Blastocystis sp. (diversity and epidemiology, diagnosis tools and pathophysiology). These data pave the way for the following challenges concerning Blastocystis sp. research: deciphering key biological mechanisms and pathways of this parasite and clarification of its clinical impact in humans.

A case of Strongyloides hyperinfection associated with tuberculosis

Strongyloidiasis is a parasitic infection that occurs in tropical regions. Hyperinfection, which is an accelerated autoinfection, is often associated with an immunosuppressive state, such as HTLV-1 infection or steroid use. Immunosuppression can also lead to reactivation of tuberculosis infection. These infections may have interacted as a result of impaired cellular immunity. A 28-year-old Nepali male was referred to our hospital for slight abdominal pain and high fever. An abdominal CT scan showed ascites and intestinal swelling. He was admitted with suspected gastroenteritis. Results of stool microscopy on the third day of hospitalization revealed abundant strongylid larvae. We diagnosed a Strongyloides hyperinfection and prescribed ivermectin. Although the numbers of strongylid organisms in the patient’s stool soon diminished, his temperature remained high. After receiving a second dose of ivermectin on day 17, he was transferred to a nearby hospital for observation, where he was noted to have massive pleural effusion. He returned to our hospital where his pleural effusion was found to be positive for adenosine deaminase (ADA), and he was diagnosed with a tuberculosis infection. Strongyloides hyperinfection can occur in a non-endemic region. It can be associated with tuberculosis infection possibly due to impaired cellular immunity. It is important to consider other possible infections when treating a patient with an infection associated with impaired cellular immunity.

Strongyloides stercoralis infection in the immunocompromised host

Strongyloides stercoralis is an intestinal nematode acquired in the tropics or subtropics. Most often, it causes chronic, asymptomatic infection, but a change in immune status can increase parasite numbers, leading to hyperinfection syndrome, dissemination, and death if unrecognized. Corticosteroid use is most commonly associated with hyperinfection syndrome. Diagnosis of Strongyloides infection is based on serology and serial stool examinations for larvae. The treatment of choice for chronic, asymptomatic infection is oral ivermectin. Alternative pharmacologic agents include albendazole and thiabendazole. For hyperinfection syndrome, ivermectin remains the drug of choice, though therapy duration must be individualized with the end point being complete parasite eradication. Recurrent strongyloidiasis should prompt an evaluation for human T-cell lymphotropic virus type 1 coinfection. No test of cure is currently available, although immunoglobulin G antibody levels have been shown to decline within 6 months of successful treatment.

Blastocystis hominis infection in long-term care facilities in Taiwan: prevalence and associated clinical factors

Blastocystis hominis is probably the most common protozoan found in the human gut worldwide. In Taiwan, the prevalence of B. hominis infection is yet to be determined but is expected to be relatively higher among foreign workers. No data is available on the prevalence of B. hominis infection in long-term care facilities in Taiwan. This study included 713 subjects (552 residents and 161 care workers) from ten long-term care facilities in Taiwan who completed stool microscopic examinations with Merthiolate-iodine-formalin stain technique. The prevalence rate of blastocystosis was the highest among foreign and domestic care workers followed by residents (12.2%, 4.6%, and 2.7%, respectively). Older age (p = 0.04) and lower educational level (p = 0.008) were significantly associated with blastocystosis among care workers. Among residents, B. hominis infection was negatively associated with prolonged use of antibiotics within 3 months prior to examination (p = 0.05) and positively associated with tracheostomy in-place (p = 0.028). In conclusion, B. hominis infection was the most prevalent intestinal parasitic infection among both care workers and residents of long-term care facilities in Taiwan. Use of antibiotics was negatively associated with B. hominis infection among residents. Additionally, appropriate preventive measures should be implemented to older care workers with lesser educational attainment in order to reduce the risk of blastocystosis infection.

Oh my aching gut: irritable bowel syndrome, Blastocystis, and asymptomatic infection

Blastocystis is a prevalent enteric protozoan that infects a variety of vertebrates. Infection with Blastocystis in humans has been associated with abdominal pain, diarrhea, constipation, fatigue, skin rash, and other symptoms. Researchers using different methods and examining different patient groups have reported asymptomatic infection, acute symptomatic infection, and chronic symptomatic infection. The variation in accounts has lead to disagreements concerning the role of Blastocystis in human disease, and the importance of treating it. A better understanding of the number of species of Blastocystis that can infect humans, along with realization of the limitations of the existing clinical laboratory diagnostic techniques may account for much of the disagreement. The possibility that disagreement was caused by the emergence of particular pathogenic variants of Blastocystis is discussed, along with the potential role of Blastocystis infection in irritable bowel syndrome (IBS). Findings are discussed concerning the role of protease-activated receptor-2 in enteric disease which may account for the presence of abdominal pain and diffuse symptoms in Blastocystis infection, even in the absence of fever and endoscopic findings. The availability of better diagnostic techniques and treatments for Blastocystis infection may be of value in understanding chronic gastrointestinal illness of unknown etiology.

New insights on classification, identification, and clinical relevance of Blastocystis spp

SUMMARY

Blastocystis is an unusual enteric protozoan parasite of humans and many animals. It has a worldwide distribution and is often the most commonly isolated organism in parasitological surveys. The parasite has been described since the early 1900s, but only in the last decade or so have there been significant advances in our understanding of Blastocystis biology. However, the pleomorphic nature of the parasite and the lack of standardization in techniques have led to confusion and, in some cases, misinterpretation of data. This has hindered laboratory diagnosis and efforts to understand its mode of reproduction, life cycle, prevalence, and pathogenesis. Accumulating epidemiological, in vivo, and in vitro data strongly suggest that Blastocystis is a pathogen. Many genotypes exist in nature, and recent observations indicate that humans are, in reality, hosts to numerous zoonotic genotypes. Such genetic diversity has led to a suggestion that previously conflicting observations on the pathogenesis of Blastocystis are due to pathogenic and nonpathogenic genotypes. Recent epidemiological, animal infection, and in vitro host-Blastocystis interaction studies suggest that this may indeed be the case. This review focuses on such recent advances and also provides updates on laboratory and clinical aspects of Blastocystis spp.