Blastocystis infection in Malaysia: evidence of waterborne and human-to-human transmissions among the Proto-Malay, Negrito and Senoi tribes of Orang Asli

Prevalence and Risk Factors of Anaemia among Orang Asli Children in Malaysia: A Scoping Review

BACKGROUND

Anaemia continues to be a global public health burden affecting all age groups, particularly children. Indigenous people, including the Orang Asli (OA) population in Malaysia, are at risk of anaemia due to the vast disparities in social determinants of health in their population compared to the non-indigenous population.

OBJECTIVES

This review aimed to identify the prevalence and risk factors of anaemia among OA children in Malaysia and analyse the knowledge gaps.

METHODS

A systematic search was conducted in PubMed, Cochrane Library, Scopus and Google Scholar databases. This review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews (PRISMA-ScR) guidelines.

RESULTS

This review identified six studies involving the participation of OA children from eight subtribes residing in Peninsular Malaysia. The overall prevalence of anaemia among OA children ranged from 21.6 to 80.0%, with iron deficiency anaemia prevalence at 34.0%. The risk factors of anaemia among OA children reported from one study in this review were being younger than ten years old children (AOR 2.11 (95% CI 1.23, 3.63)) and moderate to heavy Ascaris infections (AOR 2.05 (95% CI 1.12, 3.76)). There was no data from OA children from certain age groups and subtribes. Additionally, there is a paucity of data on risk factors for anaemia among OA children from the currently available evidence.

CONCLUSION

The prevalence of anaemia among OA children poses a moderate to severe public health concern. Therefore, more comprehensive studies in the future are needed to address the gaps identified in this review, primarily regarding anaemia risk factors. This data would encourage policymakers in devising effective national prevention strategies to improve morbidity and mortality among OA children in the future.

MOLECULAR STUDY OF BLASTOCYSTIS HOMINIS ISOLATED FROM DIFFERENT REGIONS OF DIYALA GOVERNORATE

OBJECTIVE

The aim: To detect the infection rate of Blastocystis hominis in children less than 10 years old with diarrhea in Diyalaby polymerase chain reaction (PCR) method, to determine the subtype of Blastocystis hominis by sequencing the product of the positive result, and to determine the association between Blastocystis hominis infection and different factors such as gender, age, the level of mother education and the presence or absence animals in their houses.

PATIENTS AND METHODS

Materials and methods: A cross-sectional study was conducted on children with diarrhea at Al-Batool Teaching Hospital in Diyala governorate, during the period from November 2020 to April 2021, a total of 100 children 55 males and 45 females, then, stool samples were collected and examined by conventional polymerase chain reaction.

RESULTS

Results: The rate of infection with the parasite Blastocystis hominis was 8%, 8 out of 100. The infection was higher among females 62.5% than to males 37.5%, while the positive result was higher in the age group less than two years 75%, the highest percentage occur with patient whose mothers were incomplete primary and primary education was reached 37.5% and 25%; respectively and the study showed the highest percentage was with those who kept animals at homes was 75%.

CONCLUSION

Conclusions: According to the genetic analysis of the sequence of eight samples that were positive for Blastocystis hominis parasite using the conventional polymerase chain reaction and they were back to the subtypes 3.

Resistance of Blastocystis to chlorine and hydrogen peroxide

Blastocystis is a ubiquitous, widely distributed protist inhabiting the gastrointestinal tract of humans and other animals. The organism is genetically diverse, and so far, at least 28 subtypes (STs) have been identified with ST1-ST9 being the most common in humans. The pathogenicity of Blastocystis is controversial. Several routes of transmission have been proposed including fecal-oral (e.g., zoonotic, anthroponotic) and waterborne. Research on the latter has gained traction in the last few years with the organism having been identified in various bodies of water, tap water, and rainwater collection containers including water that has been previously filtered and/or chlorinated. Herein, we assessed the resistance of 11 strains maintained in culture, spanning ST1-ST9 to various chlorine and hydrogen peroxide concentrations for 24 h, and performed recovery assays along with re-exposure. Following the treatment with both compounds, all subtypes showed increased resistance, and viability could be visualized at the cellular level. These results are hinting at the presence of mechanism of resistance to both chlorine and hydrogen peroxide. As such, this pilot study can be the platform for developing guidelines for water treatment processes.

Blastocystis One Health Approach in a Rural Community of Northern Thailand: Prevalence, Subtypes and Novel Transmission Routes

Blastocystis is the most commonly found eukaryote in the gut of humans and other animals. This protist is extremely heterogeneous genetically and is classified into 28 subtypes (STs) based on the small subunit ribosomal RNA (SSU rRNA) gene. Numerous studies exist on prevalence of the organism, which usually focus on either humans or animals or the environment, while only a handful investigates all three sources simultaneously. Consequently, understanding of Blastocystis transmission dynamics remains inadequate. Our aim was to explore Blastocystis under the One Health perspective using a rural community in northern Thailand as our study area. We surveyed human, other animal and environmental samples using both morphological and molecular approaches. Prevalence rates of Blastocystis were 73% in human hosts (n = 45), 100% in non-human hosts (n = 44) and 91% in environmental samples (n = 35). Overall, ten subtypes were identified (ST1, ST2, ST3, ST4 ST5, ST6, ST7, ST10, ST23, and ST26), eight of which were detected in humans (ST1, ST2, ST3, ST4, ST5, ST7, ST10, and ST23), three in other animals (ST6, ST7, and ST23), while seven (ST1, ST3, ST6, ST7, ST10, ST23, and ST26) were found in the environment. In our investigation of transmission dynamics, we assessed various groupings both at the household and community level. Given the overall high prevalence rate, transmission amongst humans and between animals and humans are not as frequent as expected with only two subtypes being shared. This raises questions on the role of the environment on transmission of Blastocystis. Water and soil comprise the main reservoirs of the various subtypes in this community. Five subtypes are shared between humans and the environment, while three overlap between the latter and animal hosts. We propose soil as a novel route of transmission, which should be considered in future investigations. This study provides a thorough One Health perspective on Blastocystis. Using this type of approach advances our understanding on occurrence, diversity, ecology and transmission dynamics of this poorly understood, yet frequent gut resident.

The Coexistence of Blastocystis spp. in Humans, Animals and Environmental Sources from 2010-2021 in Asia

Simple Summary

Blastocystis spp. are unicellular parasites that infect the gastrointestinal tract of humans and animals. Their occurrence in the environment had been detected in water sources, thus causing contamination. The presence of the parasites in humans, animals and environmental sources in Asia were reviewed according to countries in Asia, different categories of human and animal populations, and environmental sources including water samples, food and ambient air. The coexistence of the parasites poses a public health concern as the parasites are commonly found in most studies. Hence, there is a growing interest in the study of Blastocystis spp. Due to the isolation of Blastocystis spp. from living and non-living sources, a collaborative, multisectoral and transdisciplinary approach known as One Health is proposed for future study of Blastocystis spp. in order to achieve optimal health outcomes through the recognition of interconnection between people, animals and their shared environment.

Abstract

Blastocystis spp. are controversial unicellular protists that inhabit the gastrointestinal tract of humans and a wide range of animals worldwide. This review provides an overview of the prevalence and distribution of Blastocystis spp. and their subtypes throughout Asia. Research articles reporting on the presence of Blastocystis spp. in locations within Asia, between 1 January 2010, and 10 May 2021, were obtained from Scopus, PubMed, and Google Scholar. In 427 articles, the prevalence of Blastocystis spp. in 31 countries within the last decade was revealed. Isolates were found in humans, various mammals, birds, reptiles, insects, water sources, vegetables, and ambient air. Prevalence of Blastocystis spp. varied widely across host categories. Subtypes identified throughout Asia were STs 1–14, and ST18–22 (novel subtypes). ST1, ST2, ST3, ST4 were the most frequently isolated in humans; ST5 in pigs; ST10 and ST14 in goats, sheep, and cattle; and ST6 and ST7 in chickens. ST1 and ST3 were most common in water samples. ST1, ST2, ST3, ST4, ST5 and ST6 were shared by humans, animals, and water sources. There is a growing interest in the study of Blastocystis spp. and their subtypes in Asia. Due to the isolation of Blastocystis spp. from biotic and abiotic sources in Asia, the application of the One Health (OH) approach to the study of Blastocystis spp. is proposed for improved perception of this organism.

Perceptions and prevention practices on malaria among the indigenous Orang Asli community in Kelantan, Peninsular Malaysia

BACKGROUND

Malaysia is on track towards malaria elimination. However, several cases of malaria still occur in the country. Contributing factors and communal aspects have noteworthy effects on any malaria elimination activities. Thus, assessing the community's knowledge, attitudes and practices (KAP) towards malaria is essential. This study was performed to evaluate KAP regarding malaria among the indigenous people (i.e. Orang Asli) in Peninsular Malaysia.

METHODS

A household-based cross-sectional study was conducted in five remote villages (clusters) of Orang Asli located in the State of Kelantan, a central region of the country. Community members aged six years and above were interviewed. Demographic, socio-economic and KAP data on malaria were collected using a structured questionnaire and analysed using descriptive statistics.

RESULTS

Overall, 536 individuals from 208 households were interviewed. Household indoor residual spraying (IRS) coverage and bed net ownership were 100% and 89.2%, respectively. A majority of respondents used mosquito bed nets every night (95.1%), but only 50.2% were aware that bed nets were used to prevent malaria. Nevertheless, almost all of the respondents (97.9%) were aware that malaria is transmitted by mosquitoes. Regarding practice for managing malaria, the most common practice adopted by the respondents was seeking treatment at the health facilities (70.9%), followed by self-purchase of medication from a local shop (12.7%), seeking treatment from a traditional healer (10.5%) and self-healing (5.9%). Concerning potential zoonotic malaria, about half of the respondents (47.2%) reported seeing monkeys from their houses and 20.1% reported entering nearby forests within the last 6 months.

CONCLUSION

This study found that most populations living in the villages have an acceptable level of knowledge and awareness about malaria. However, positive attitudes and practices concerning managing malaria require marked improvement.

Molecular detection of Blastocystis in black bears and sika deer in northern China

Protists of the Blastocystis genus are distributed worldwide and can infect a range of hosts. However, data concerning Blastocystis infection are limited for sika deer and are not available for black bears. Therefore, in the present study, a total of 312 black bears (Ursus thibetanus) from Heilongjiang Province and 760 sika deer (Cervus nippon) from four different northern Chinese provinces were investigated. Blastocystis infection in these animals was detected via PCR amplification of the small subunit rRNA gene in fecal samples. The prevalence of Blastocystis infection in black bears and sika deer was 14.4% (45/312 positive samples) and 0.8% (6/760 positive samples), respectively. Young black bears (18.3%) had a significantly higher Blastocystis prevalence than adult bears (9.1%). The prevalence of Blastocystis was significantly higher in black bears raised outdoors (24.6%) than in bears raised indoors (12.2%). Blastocystis-positive sika deer were only found in Jilin Province (1.3%, 6/480). Female sika deer (0%, 0/61) had a significantly lower Blastocystis prevalence than males (0.9%, 6/699). Sanger sequencing was used to determine the small subunit rRNA gene sequences of the Blastocystis-positive PCR products. A neighbor-joining phylogenetic tree based on the small subunit rRNA gene sequences showed that only Blastocystis subtype (ST)1 was identified in black bears, whereas ST10 and ST14 were found in sika deer. This is the first report of Blastocystis ST1 infection in black bears. These findings also extend the distribution information of Blastocystis subtypes, which will provide a foundation for further study of Blastocystis in different hosts in China.

Blastocystis infection frequency and subtype distribution in university students

Blastocystis is a parasite commonly found in the gut of humans and animals; there are 22 known subtypes (STs). STs 1-9 and 12 have been found in humans. This parasite has a faecal-oral route of transmission; its high infection prevalence in developing countries is due to poor hygiene practices, exposure to infected animals, and intake of contaminated water or food. Its pathogenicity has not been established, because it has been found in symptomatic and asymptomatic patients. The goal of this study was to analyze the frequency of Blastocystis and its subtypes (1, 2, 3, 4, 5, and 7), and assess the relationship between these subtypes and abdominal pain and distension. 202 university students participated in this study. A questionnaire was applied to assess the gastrointestinal symptoms, and subsequently the students were asked to provide faecal samples. The presence of parasites was determined by optical microscopy. Blastocystis-positive samples had their DNA extracted and end-point PCR was performed to corroborate the presence of Blastocystis and determine its subtypes. Among the samples, 47.03% were positive according to PCR analysis. The most prevalent subtypes were ST3 (29.79%), ST4 (16.84%), and ST1 (14.89%). We found a relationship between ST1 and abdominal pain (OR = 0.196; CI = 0.0533–0.7318; p = 0.015), and between ST4 and abdominal distension (OR = 0.2928; CI = 0.1017–0.8429; p = 0.023). However, the presence of this parasite and the probable relationship with gastrointestinal symptoms suggest the need to determine its role within intestinal microbiota in order to confirm whether its eradication is really necessary or not.

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.

Prevalence and subtype distribution of Blastocystis in ethnic minority groups on both sides of the China-Myanmar border, and assessment of risk factors

Blastocystis is one of the most common intestinal parasites in humans worldwide. To understand its prevalence and to explore the risk factors for Blastocystis in humans in developing countries, a molecular epidemiological investigation of Blastocystis was conducted in ethnic minority groups on both sides of the China-Myanmar border. A total of 461 fecal specimens were collected from 289 Yao people in China and 172 Wa people in Myanmar, together with a questionnaire for each participant. Based on sequence analysis of the partial small subunit of ribosomal RNA (SSU rRNA) gene (barcode region or 260 bp region), an average prevalence of 6.29% (29/461) was observed, with 4.50% (13/289) in Yao people and 9.30% (16/172) in Wa people. Twenty-two Blastocystis isolates were successfully subtyped by sequence analysis of the barcode region. Three subtypes were identified: ST1 (n = 7), ST3 (n = 13) and ST4 (n = 2). A statistical difference in the prevalence of Blastocystis was only observed between children (12.37%, 12/97) and adults (4.95%, 16/323), and between not washing hands (11.02%, 14/127) and washing hands (4.76%, 15/315) after using toilets, emphasizing the importance and necessity of health education in people in the investigated areas, especially in children.

An Epidemiological Review on Emerging and Re-Emerging Parasitic Infectious Diseases in Malaysia

Emerging infectious diseases are infections that have recently appeared in a population over a defined period of time whereas, re-emerging infectious diseases are those that were once a health problem in a particular region or a country and are now emerging again. Parasitic infectious diseases represent a serious health problem in many developing countries and recently have started spreading to developed nations via international traveling or immigration. Malaysia is facing many challenges caused by various parasitic pathogens. The lack of awareness among disadvantaged populations such as the Orang Asli community and the dependency on foreign workers has led to an influx of immigrants to Malaysia from countries endemic to various parasitic diseases. Understanding the social and economic dynamics of such diseases can help anticipate and subsequently control their emergence. Raising public awareness, developing robust public health infrastructure and implementing point-of-care diagnostics will help curb the spread of such diseases. This review provides epidemiological insights into the reported emerging and re-emerging parasitic infectious diseases in Malaysia over the past two decades.

Effect of Blastocystis sp. in dengue patients-Increase in the treatment cost and exacerbation of symptoms

Increasing incidences of dengue have become a global health threat with major clinical manifestation including high fever and gastrointestinal symptoms. These symptoms were also expressed among Blastocystis sp. infected individuals, a parasite commonly seen in human stools. This parasite has been previously reported to replicate faster upon exposure to high temperature. The present study is a hospitalized-based cross-sectional study involved the collection of faecal sample from dengue patients. Stool examination was done by in vitro cultivation to isolate Blastocystis sp. Growth pattern of all the positive isolates were analyzed to identify the multiplication rate of Blastocystis sp. isolated from dengue patients. Distribution of Blastocystis sp. among dengue patients was 23.6%. Dengue patients who were positive for Blastocystis sp. infection denoted a significantly higher fever rate reaching 38.73°C (p<0.05) compared to the non-Blastocystis sp. infected patients (38.44°C). It was also found that Blastocystis sp. infected patients complained of frequenting the toilet more than five times a day (p<0.05) compared to those who were non-Blastocystis sp. infected. At the same time, the duration of hospitalization was significantly longer (p<0.05) for Blastocystis sp. infected dengue patients compared to the non-Blastocystis sp. infected patients. Besides, Blastocystis sp. isolated from dengue patients (in vivo thermal stress) showed a higher growth rate compared to the non-dengue isolated which was exposed to high temperature (in vitro thermal stress). Our findings suggest that presence of Blastocystis sp. during dengue infection could trigger the increase of temperature which could be due to highly elevated pro inflammatory cytokines by both parasitic and virus infection. This could justify why the temperature in Blastocystis sp. infected dengue patients is higher compared to the non-Blastocystis sp. infected patients. Higher temperature could have triggered a greater parasite multiplication rate that contributed to the aggravation of the gastrointestinal symptoms.

Impacts of human development index and climate conditions on prevalence of Blastocystis: A systematic review and meta-analysis

Blastocystis is a prevalent eukaryotic microorganism that has been frequently reported from the stool samples of human and animals, all over the world. The prevalence of this parasite has close correlation with the climate and hygiene situation of studied populations. For the current study, English and Persian databases were searched for the following terms: "Blastocystis hominis", "Blastocystis sp.", "Intestinal Parasites", "Prevalence" and "Iran". In order to data analysis and assess the possibility of publication bias, STATA v11 and Begg's Funnel plot were employed respectively. From 605 searched cases, 86 publications met our criteria for the analysis. The pooled prevalence of Blastocystis was 9.1% (95%CI: 8.2%, 10.1%). The results represented that the prevalence of the parasite using molecular techniques or cultivation followed by molecular techniques (20.89%) was higher than only microscopical examination (8.96%). The prevalence rate of Blastocystis according to human development index was 7.6%, 7.2%, 11.9%, 13.4%, and 3.3% for ranks 1 to 5, respectively. This is the first study signifying the prevalence of Blastocystis regarding the human development index and climate conditions. The findings represented that although human development index, low levels of socioeconomic situations together with appropriate climate such as sufficient humidity and high temperature increase the chance of transmission of Blastocystis in a society.

Comparative Study of Wheatley's Trichrome Stain and In-vitro Culture against PCR Assay for the Diagnosis of Blastocystis sp. in Stool Samples

BACKGROUND

This study evaluated the performance of routine permanent stain and cultivation method in comparison with polymerase chain reaction assay as the reference technique to detect Blastocystis sp.

METHODS

A cross-sectional study was conducted among aboriginal populations that reside in Pahang, Peninsular Malaysia in Feb to Mar 2015. A total of 359 stool samples were examined using Wheatley's trichrome stain, in-vitro cultivation in Jones' medium and PCR assay. Positive amplicons were subjected to sequencing and phylogenetic analysis.

RESULTS

Fifty-six (15.6%) samples were detected positive with Blastocystis sp. by Wheatley's trichrome stain and 73 (20.3%) by in-vitro culture, while PCR assay detected 71 (19.8%) positive samples. Detection rate of Blastocystis sp. was highest in combination of microscopic techniques (27.9%). The sensitivity and specificity of Wheatley's trichrome staining and in-vitro culture techniques compared to PCR assay were 49.3% (95% CI: 37.2-61.4) and 92.7% (95% CI: 89.1-95.4) and 39.4% (95% CI: 28.0-51.8) and 84.4% (95% CI: 79.7-88.4), respectively. However, the sensitivity [60.6% (95% CI: 48.3-71.9)] of the method increased when both microscopic techniques were performed together. False negative results produced by microscopic techniques were associated with subtype 3. The agreement between Wheatley's trichrome stain, in-vitro culture and combination of microscopic techniques with PCR assay were statistically significant by Kappa statistics (Wheatley's trichrome stain: K = 0.456, P<0.001; in-vitro culture: K = 0.236, P<0.001 and combination techniques: K = 0.353, P<0.001).

CONCLUSION

The combination of microscopic technique is highly recommended to be used as a screening method for the diagnosis of Blastocystis infection either for clinical or epidemiological study to ensure better and accurate diagnosis.

Molecular epidemiology of blastocystosis in Malaysia: does seasonal variation play an important role in determining the distribution and risk factors of Blastocystis subtype infections in the Aboriginal community?

BACKGROUND

Alternating wet and dry seasons may play an important role in the acquisition and distribution of Blastocystis subtype infection in the tropics. This cross-sectional study was therefore conducted to provide the prevalence of Blastocystis and to determine the potential risk factors associated with each subtype during the wet and dry seasons in the Aboriginal community, Pahang, Malaysia.

METHODS

A total of 473 faecal samples were collected: 256 (54.1%) and 217 (45.9%) samples were obtained during the wet (October-November 2014) and the dry season (June 2015), respectively. All fresh faecal samples were subjected to molecular analysis for subtype and allele identification.

RESULTS

Of the 473 samples, 42.6% and 37.8% were positive for Blastocystis ST1, ST2, ST3 and ST4 during wet and dry seasons, respectively. Prevalence of Blastocystis ST1 was significantly higher during the wet season compared to the dry season (Z = 2.146, P < 0.05). Analysis of the association of each Blastocystis subtype with socioeconomic characteristics showed the presence of other family members infected with Blastocystis ST3 and the use of stored river water for domestic activities were the significant risk factors for Blastocystis ST3 infections during both seasons. Untreated water supply and low monthly household income (less or equal to RM 500) were the other significant risk factors for Blastocystis ST3 infections during wet and dry season, respectively. The presence of other family members with Blastocystis ST1 and ST2 was the only significant risk factor associated with ST1 and ST2 infections during both seasons. We hypothesise that transmission of Blastocystis ST1, ST2 and ST3 occurred from person to person during both seasons. The waterborne transmission was also identified as a mode of transmission of Blastocystis ST3.

CONCLUSION

The significant risk factors identified in this study were important in the dynamic transmission of Blastocystis infections during both seasons. Provision of treated water supply and health education are affirmative actions to be taken to control Blastocystis infections in this community.

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.

Occurrence of Blastocystis sp. in water catchments at Malay villages and Aboriginal settlement during wet and dry seasons in Peninsular Malaysia

In the tropics, there are too few studies on isolation of Blastocystis sp. subtypes from water sources; in addition, there is also an absence of reported studies on the occurrence of Blastocystis sp. subtypes in water during different seasons. Therefore, this study was aimed to determine the occurrence of Blastocystis sp. subtypes in river water and other water sources that drained aboriginal vicinity of highly endemic intestinal parasitic infections during wet and dry seasons. Water samples were collected from six sampling points of Sungai Krau (K1–K6) and a point at Sungai Lompat (K7) and other water sources around the aboriginal villages. The water samples were collected during both seasons, wet and dry seasons. Filtration of the water samples were carried out using a flatbed membrane filtration system. The extracted DNA from concentrated water sediment was subjected to single round polymerase chain reaction and positive PCR products were subjected to sequencing. All samples were also subjected to filtration and cultured on membrane lactose glucuronide agar for the detection of faecal coliforms. During wet season, Blastocystis sp. ST1, ST2 and ST3 were detected in river water samples. Blastocystis sp. ST3 occurrence was sustained in the river water samples during dry season. However Blastocystis sp. ST1 and ST2 were absent during dry season. Water samples collected from various water sources showed contaminations of Blastocystis sp. ST1, ST2, ST3 and ST4, during wet season and Blastocystis sp. ST1, ST3, ST8 and ST10 during dry season. Water collected from all river sampling points during both seasons showed growth of Escherichia coli and Enterobacter aerogenes, indicating faecal contamination. In this study, Blastocystis sp. ST3 is suggested as the most robust and resistant subtype able to survive in any adverse environmental condition. Restriction and control of human and animal faecal contaminations to the river and other water sources shall prevent the transmission of Blastocystis sp. to humans and animals in this aboriginal community.

Prevalence and genetic diversity of Blastocystis in family units living in the United States

The human gut is host to a diversity of microorganisms including the single-celled microbial eukaryote Blastocystis. Although Blastocystis has a global distribution, there is dearth of information relating to its prevalence and diversity in many human populations. The mode of Blastocystis transmission to humans is also insufficiently characterised, however, it is speculated to vary between different populations. Here we investigated the incidence and genetic diversity of Blastocystis in a US population and also the possibility of Blastocystis human-human transmission between healthy individuals using family units (N=50) living in Boulder, Colorado as our sample-set. Ten of the 139 (~7%) individuals in our dataset were positive for Blastocystis, nine of whom were adults and one individual belonging to the children/adolescents group. All positive cases were present in different family units. A number of different Blastocystis subtypes (species) were detected with no evidence of mixed infections. The prevalence of Blastocystis in this subset of the US population is comparatively low relative to other industrialised populations investigated to date; however, subtype diversity was largely consistent with that previously reported in studies of European populations. The distribution of Blastocystis within family units indicates that human-human transmission is unlikely to have occurred within families that participated in this study. It is not unexpected that given the world-wide variation in human living conditions and lifestyles between different populations, both the prevalence of Blastocystis and its mode of transmission to humans may vary considerably.

Ex Vivo and In Vivo Mice Models to Study Blastocystis spp. Adhesion, Colonization and Pathology: Closer to Proving Koch's Postulates

Blastocystis spp. are widely prevalent extra cellular, non-motile anerobic protists that inhabit the gastrointestinal tract. Although Blastocystis spp. have been associated with gastrointestinal symptoms, irritable bowel syndrome and urticaria, their clinical significance has remained controversial. We established an ex vivo mouse explant model to characterize adhesion in the context of tissue architecture and presence of the mucin layer. Using confocal microscopy with tissue whole mounts and two axenic isolates of Blastocystis spp., subtype 7 with notable differences in adhesion to intestinal epithelial cells (IEC), isolate B (ST7-B) and isolate H (more adhesive, ST7-H), we showed that adhesion is both isolate dependent and tissue trophic. The more adhesive isolate, ST7-H was found to bind preferentially to the colon tissue than caecum and terminal ileum. Both isolates were also found to have mucinolytic effects. We then adapted a DSS colitis mouse model as a susceptible model to study colonization and acute infection by intra-caecal inoculation of trophic Blastocystis spp.cells. We found that the more adhesive isolate ST7-H was also a better colonizer with more mice shedding parasites and for a longer duration than ST7-B. Adhesion and colonization was also associated with increased virulence as ST7-H infected mice showed greater tissue damage than ST7-B. Both the ex vivo and in vivo models used in this study showed that Blastocystis spp. remain luminal and predominantly associated with mucin. This was further confirmed using colonic loop experiments. We were also successfully able to re-infect a second batch of mice with ST7-H isolates obtained from fecal cultures and demonstrated similar histopathological findings and tissue damage thereby coming closer to proving Koch’s postulates for this parasite.

A tale of two communities: intestinal polyparasitism among Orang Asli and Malay communities in rural Terengganu, Malaysia

Background

Intestinal parasitic infections (IPIs) are still major health problems in many developing countries including Malaysia, particularly in the poor and socioeconomically deprived rural and remote communities in Peninsular Malaysia. This study was conducted to determine the prevalence of IPIs and to identify the key factors associated with intestinal polyparasitism as well as to evaluate the knowledge, attitude and practices (KAP) on IPIs among rural Orang Asli and Malay communities in Terengganu, Malaysia.

Methods

A cross-sectional study was conducted among 340 participants (165 Orang Asli and 175 Malay) aged ≤ 15 years from the Hulu Terengganu and Kemaman districts of Terengganu. Faecal samples were examined for the presence of intestinal parasites by using direct smear, formalin-ether sedimentation, trichrome stain, modified Ziehl Neelsen stain, in vitro cultivation in Jones’ medium, Kato Katz and Harada Mori techniques. Demographic, socioeconomic, environmental and behavioural information of the participants and their KAP for IPIs were collected by using a pre-tested questionnaire.

Results

Overall, 149 (90.3 %) Orang Asli and 43 (24.6 %) Malay children were infected by at least one parasite species. The overall prevalences of intestinal polyparasitism among the Orang Asli and Malay were 68.5 % (113/165) and 14.3 % (25/175), respectively. Multiple logistic regression analysis showed that using unsafe water supply as a source for drinking water, the presence of domestic animals, not wearing shoes when outside, not washing vegetables before consumption, not washing hands after playing with soil, indiscriminate defecation and the low level of mother’s education were the key risk factors for intestinal polyparasitism among the Orang Asli, while working mothers and the presence of domestic animals were the risk factors among the Malay children. Almost all the Malays were well aware about the IPIs while Orang Asli respondents had a poor level of related awareness.

Conclusions

This study demonstrates that IPIs are highly prevalent in rural Terengganu, Malaysia. Community awareness about IPIs was found to be imperative in protecting Malay children from these infections. An integrated control programme for the prevention and control of IPIs is highly recommended for these communities, with a special emphasis on the Orang Asli population.

HIGH PREVALENCE OF Blastocystis spp. INFECTION IN CHILDREN AND STAFF MEMBERS ATTENDING PUBLIC URBAN SCHOOLS IN SÃO PAULO STATE, BRAZIL

After a gastroenteritis outbreak of unknown etiology in the municipality of Sebastião da Grama, SãoPaulo, Brazil, we conducted a parasitological survey to establish the epidemiological profile of enteroparasitosis in children and staff members attending the public urban schools in operation in town. The cross-sectional study evaluated 172 children aged 11 months to 6 years old and 33 staff members aged 19 to 58 years old. Overall, 96 (55.81%) children and 20 (60.61%) staff members were mono-parasitized, while 58 (33.72%) children and 4 (12.12%) workers were poly-parasitized. Protozoa (88.37%; 72.73%) was more prevalent than helminthes (3.48%; 0%) in children and staff members respectively.Blastocystis spp. was the most prevalent parasite in children (86.63%) and staff members (66.67%). The age of 1 year old or less was found to be associated with increased prevalence of giardiasis [OR = 13.04; 95%CI 2.89-58.91; p = 0.00] and public garbage collection was identified as a protective factor against intestinal helminth infections [OR = 0.06; 95%CI 0.00-0.79; p = 0.03]. Although most of the children tested positive for Blastocystis spp. and also presented clinical signs/symptoms (62.2%), this association was not statistically significant [OR = 1.35; 95%CI 0.53-3.44; p = 0.51]. Intestinal parasites still represent a public health concern and this study underscores the importance of further investigations to better understand the pathogenic role of Blastocystis spp.

Predominance of Blastocystis sp. Infection among School Children in Peninsular Malaysia

Background

One of the largest cross-sectional study in recent years was carried out to investigate the prevalence of intestinal parasitic infections among urban and rural school children from five states namely Selangor, Perak, Pahang, Kedah and Johor in Peninsula Malaysia. This information would be vital for school authorities to influence strategies for providing better health especially in terms of reducing intestinal parasitism.

Methods and Principal Findings

A total of 3776 stool cups was distributed to 26 schools throughout the country. 1760 (46.61%) responded. The overall prevalence of intestinal parasitic infection in both rural and urban areas was 13.3%, with Blastocystis sp (10.6%) being the most predominant, followed by Trichuris trichiura (3.4%), Ascaris lumbricoides (1.5%) and hook worm infection (0.9%). Only rural school children had helminthic infection. In general Perak had the highest infection (37.2%, total, n = 317), followed by Selangor (10.4%, total, n = 729), Pahang (8.6%, total, n = 221), Kedah (6.2%, total, n = 195) and Johor (3.4%, total, n = 298). School children from rural schools had higher infection (13.7%, total, n = 922) than urban school children (7.2%, total, n = 838). Subtype (ST) 3 (54.3%) is the most predominant ST with persons infected with only ST1 and ST3 showing symptoms. Blastocystis sp infection significantly associated with low household income, low parent’s education and presence of symptoms (p<0.05).

Conclusion

It is critical that we institute deworming and treatment to eradicate the parasite especially in rural school children.

Seeing the Whole Elephant: Imaging Flow Cytometry Reveals Extensive Morphological Diversity within Blastocystis Isolates

Blastocystis is a common protist isolated in humans and many animals. The parasite is a species complex composed of 19 subtypes, 9 of which have been found in humans. There are biological and molecular differences between Blastocystis subtypes although microscopy alone is unable to distinguish between these subtypes. Blastocystis isolates also display various morphological forms. Several of these forms, however, have not been properly evaluated on whether or not these play significant functions in the organism's biology. In this study, we used imaging flow cytometry to analyze morphological features of Blastocystis isolates representing 3 subtypes (ST1, ST4 and ST7). We also employed fluorescence dyes to discover new cellular features. The profiles from each of the subtypes exhibit considerable differences with the others in terms of shape, size and granularity. We confirmed that the classical vacuolar form comprises the majority in all three subtypes. We have also evaluated other morphotypes on whether these represent distinct life stages in the parasite. Irregularly-shaped cells were identified but all of them were found to be dying cells in one isolate. Granular forms were present as a continuum in both viable and non-viable populations, with non-viable forms displaying higher granularity. By analyzing the images, rare morphotypes such as multinucleated cells could be easily observed and quantified. These cells had low granularity and lower DNA content. Small structures containing nucleic acid were also identified. We discuss the possible biological implications of these unusual forms.

Effect of sanitation and water treatment on intestinal protozoa infection: a systematic review and meta-analysis

BACKGROUND

Pathogenic intestinal protozoa infections are responsible for substantial mortality and morbidity, particularly in settings where people lack improved sanitation and safe drinking water. We assessed the relation between access to, and use of, sanitation facilities and water treatment and infection with intestinal protozoa.

METHODS

We did a systematic review and searched PubMed, ISI Web of Science, and Embase from inception to June 30, 2014, without restrictions on language. All publications were examined by two independent reviewers and were included if they presented data at the individual level about access or use of sanitation facilities or water treatment, in combination with individual-level data on human intestinal protozoa infections. Meta-analyses using random effects models were used to calculate overall estimates.

FINDINGS

54 studies were included and odds ratios (ORs) extracted or calculated from 2 × 2 contingency tables. The availability or use of sanitation facilities was associated with significantly lower odds of infection with Entamoeba histolytica or Entamoeba dispar (OR 0·56, 95% CI 0·42-0·74) and Giardia intestinalis (0·64, 0·51-0·81), but not for Blastocystis hominis (1·03, 0·87-1·23), and Cryptosporidium spp (0·68, 0·17-2·68). Water treatment was associated with significantly lower odds of B hominis (0·52, 0·34-0·78), E histolytica or E dispar (0·61, 0·38-0·99), G intestinalis (0·63, 0·50-0·80), and Cryptosporidium spp infections (0·83, 0·70-0·98).

INTERPRETATION

Availability and use of sanitation facilities and water treatment is associated with lower odds of intestinal protozoa infections. Interventions that focus on water and sanitation, coupled with hygiene behaviour, should be emphasised to sustain the control of intestinal protozoa infections.

FUNDING

Swiss National Science Foundation (project numbers PBBSP3-146869 and P300P3-154634), Medicor Foundation, European Research Council (614739-A_HERO).

Prevalence and Risk Factors for Blastocystis Infection Among Children and Caregivers in a Child Care Center, Bangkok, Thailand

In September 2009, a cross-sectional study was conducted to evaluate parasitic infections in a child care center in Khlong Toei, Bangkok, Thailand. Of 503 children and staff members, 258 (51.3%) stool samples and questionnaires were obtained. The most common parasitic infection was Blastocystis sp. (13.6%). Blastocystis sp. subtype 3 was predominantly found (80.0%), followed by subtypes 2 (12.0%) and 1 (8.0%). The prevalence of Blastocystis infection varied among different age groups. The prevalence of Blastocystis infection in non-HIV-infected children aged < 10 and 10-19 years were 14.5% and 10.3%, respectively, which were not significantly different. All 31 HIV-infected children were not infected with Blastocystis sp. The most likely reason could be the result of properly using prevention measures for this specific group.

Neglected tropical diseases among two indigenous subtribes in peninsular Malaysia: highlighting differences and co-infection of helminthiasis and sarcocystosis

Soil-transmitted helminth (STH) infections have been documented among these minority groups since 1938. However the prevalence of STH is still high among these communities. Most studies tend to consider the Orang Asli (indigenous) as a homogenous group. In contrary, different subtribes have their own cultural practices. To understand this variation better, we studied the prevalence and associated factors of STH and other gut parasitic infections among two common subtribes (i.e. Temuan and Temiar). Results showed that the prevalence of the overall STH infections was higher in the Temuan subtribe (53.2% of 171) compared to the Temiar subtribe (52.7% of 98). Trichuris trichiura (46.2%) was the most prevalent parasite in the Temuan subtribe, followed by Ascaris spp. (25.7%) and hookworm (4.1%). In contrast, Ascaris spp. (39.8%) was more prevalent among the Temiar subtribe, preceded by T. trichiura (35.7%) and finally hookworm (8.3%). There were also co-infections of helminthiasis and intestinal protozoa among both Temuan and Temiar subtribes with rates being three times higher among the Temiar compared to Temuan. The most common co-infection was with Entamoeba histolytica/dispar/moshkovskii (n = 24; 24.5%, 16.0–33.0), followed by Giardia spp. (n = 3; 3.1%, −0.3–6.5). In Temuan, STH infection individuals were also infected with Entamoeba histolytica/dispar/moshkovskii (n = 11; 6.4%, 5.0–13.8), Cryptosporidium spp. (n = 3, 1.8%, −0.2–3.8) and Giardia spp. (n = 2, 1.2%, −0.4–2.8). In comparison, there was no Cryptosporidium spp. detected among the Temiar. However, it was interesting to note that there was an occurrence of co-infection of intestinal helminthiasis and sarcocystosis (intestinal) in a Temiar individual. The last report of sarcocystosis (muscular) among the Orang Asli was in 1978. The present study highlighted the importance of understanding the variation of infections amongst the different Orang Asli subtribes. It is vital to note these differences and use this knowledge to customise effective control measures for the various subtribes.

Update on the pathogenic potential and treatment options for Blastocystis sp. Gut Pathog. 2014;6:17. [PMID: 24883113 DOI: 10.1186/1757-4749-6-17]

Although Blastocystis is one of the most common enteric parasites, there is still much controversy surrounding the pathogenicity and potential treatment options for this parasite. In this review we look at the evidence supporting Blastocystis as an intestinal pathogen as shown by numerous case studies and several in vivo studies and the evidence against. We describe the chronic nature of some infections and show the role of Blastocystis in immunocompromised patients and the relationship between irritable bowel syndrome and Blastocystis infection. There have been several studies that have suggested that pathogenicity may be subtype related. Metronidazole is the most widely accepted treatment for Blastocystis but several cases of treatment failure and resistance have been described. Other treatment options which have been suggested include paromomycin and trimethroprim- sulfamethoxazole.

Blastocystis: Taxonomy, biology and virulence

The unicellular protist Blastocystis has long been an unsolved puzzle for taxonomists, microbiologists and clinicians. Over the years, the organism has been bounced on and off the different branches of the tree of life due the possession of unique phenotypic characters intermediary to different organisms. The organism is polymorphic with only few of forms such as vacuolar, granular, amoeboid, and the cyst form being commonly known. However it could exist in other forms much more frequently than the widely known forms which could be missed by the unaware observer. Certain older concepts in the life cycle of Blastocystis although has been proven wrong are still being followed in various textbooks and other trustworthy internet sources. The causal role of Blastocystis in human disease has long been a subject of controversy. It is widely believed that certain subtypes of the organism are virulent. But this is not so as other factors are also involved in the clinical outcome of the infection. In these contexts, this review intends to shed light on the past misconceptions and the recent findings on the taxonomy, biology and the virulence of this organism.

Prevalence, predictors and clinical significance of Blastocystis sp. in Sebha, Libya

BACKGROUND

Blastocystis sp. has a worldwide distribution and is often the most common human intestinal protozoan reported in children and adults in developing countries. The clinical relevance of Blastocystis sp. remains controversial. This study was undertaken to determine the prevalence of Blastocystis infection and its association with gastrointestinal symptoms among outpatients in Sebha city, Libya.

METHODS

A total of 380 stool samples were collected from outpatients attending the Central Laboratory in Sebha, Libya for routine stool examination. The presence of Blastocystis sp. was screened comparing light microscopy of direct smears against in vitro cultivation. Demographic and socioeconomic information were collected with a standardized questionnaire.

RESULTS

The overall prevalence of Blastocystis infection was 22.1%. The prevalence was significantly higher among patients aged ≥18 years compared to those aged < 18 years (29.4% vs 9.9%; x² = 19.746; P < 0.001), and in males compared to females (26.4% vs 17.5%; x² = 4.374; P = 0.036). Univariate analysis showed significant associations between Blastocystis infection and the occupational status (P = 0.017), family size (P = 0.023) and educational level (P = 0.042) of the participants. Multiple logistic regression analysis confirmed that the age of ≥ 18 years (OR = 5.7; 95% CI = 2.21; 9.86) and occupational status (OR = 2.2; 95% CI = 1.02, 4.70) as significant predictors of Blastocystis infection among this population. In those who had only Blastocystis infection but no other gastrointestinal parasitic infections, the prevalence of gastrointestinal symptoms was higher compared to those without Blastocystis infection (35.3% vs 13.2%; x² = 25.8; P < 0.001). The most common symptoms among these patients were abdominal pain (76.4%), flatulence (41.1%) and diarrhoea (21.5%).

CONCLUSIONS

Blastocystis sp. is prevalent and associated with gastrointestinal symptoms among communities in Sebha city, Libya. Age and occupational status were the significant predictors of infection. However, more studies from different areas in Libya are needed in order to delineate the epidemiology and clinical significance of this infection.