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Strain differences in Blastocystis isolates as detected by a single set of polymerase chain reaction primers

Init I, Mak JW, Lokman Hakim S, Yong HS

Parasitol Res, 1999 Feb;85(2):131-4.
PMID: 9934962

A total of 20 isolates of Blastocystis were characterized using a single set of polymerase chain reaction (PCR) primers. The amplification product revealed five types of pattern. All four isolates from Singapore yielded PCR products quite different from those of the local isolates. However, most of the local isolates showed a major product at either 280 or 500 bp, or both. We also suspected that the amplification product detected at 280 bp might be an indicator of the pathogenicity of this parasite. One isolate (M12) obtained from a monkey showed patterns similar to those of human isolates (10203 and KP1) and probably belongs to the same strain. The results indicate that the intraspecific or interstrain variations in these 20 Blastocystis isolates belong to 5 different patterns. The differences among isolates of the same strain revealed by the presence or absence of certain amplification products showed further intrastrain variations in this parasite.

Matched MeSH terms: Blastocystis/classification*; Blastocystis/genetics*; Blastocystis/isolation & purification; Blastocystis/pathogenicity
Blastocystis sp., Parasite Associated with Gastrointestinal Disorders: An Overview of its Pathogenesis, Immune Modulation and Therapeutic Strategies

Kumarasamy V, Anbazhagan D, Subramaniyan V, Vellasamy S

Curr Pharm Des, 2018;24(27):3172-3175.
PMID: 30084327 DOI: 10.2174/1381612824666180807101536

Blastocystis sp. is a unicellular parasitic microorganism commonly found in the gastrointestinal tracts of humans and animals. It causes symptomatic or asymptomatic infection and its route of transmission is via fecal-oral. High prevalence of Blastocystis infection in developing countries is usually due to poor hygiene practices, exposure to animals infected with the parasite and intake of contaminated water or food. Blastocystis infected individuals often suffer from diarrhea, abdominal pain, nausea, and stomach bloating. Even though pathogenicity of Blastocystis is unclear, it is commonly associated with irritable bowel syndrome. In this review, we have analysed the evidence that shows the association between this microorganism and gastrointestinal disorders. There have been a number of studies which showed that the pathogenicity of Blastocystis is related to its different STs. The pathogenicity is speculated to be due to cysteine proteases formation which stimulates mucosal cells to release interleukin-8 which has been associated with extreme dehydration and gut inflammation. In vitro studies on human colonic epithelial cells revealed that incubation of Blastocystis modulated the host immune response by stimulating the formation of pro-inflammatory cytokines and granulocyte macrophage colonystimulating factor. Metronidazole is found to be the first-line drug of choice. Another treatment option is the combination therapy with trimethoprim/sulfamethoxazole.

Matched MeSH terms: Blastocystis/drug effects*; Blastocystis/immunology; Blastocystis/parasitology
Fulltext High lipid storage in vacoular forms of subtype 6 Blastocystis sp. in ostrich

Chandrasekaran H, Govind SK, Panchadcharam C, Bathmanaban P, Raman K, Thergarajan G

Parasit Vectors, 2014;7:469.
PMID: 25358755 DOI: 10.1186/s13071-014-0469-7

Blastocystis sp., a widely prevalent intestinal protozoan parasite is found in a wide range of animals, including humans. The possibility of zoonotic transmission to human from birds especially ostriches led us to investigate on the cross infectivity of Blastocystis sp. isolated from the ostrich feces as well as the phenotypic and subtype characteristics. There is a need to investigate this especially with the rising number of ostrich farms due to the growing global ostrich industry.

Matched MeSH terms: Blastocystis Infections/parasitology; Blastocystis Infections/veterinary*; Blastocystis/classification*; Blastocystis/metabolism*
Fulltext Granular Formation during Apoptosis in Blastocystis sp. Exposed to Metronidazole (MTZ)

Dhurga DB, Suresh K, Tan TC

PLoS One, 2016;11(7):e0155390.
PMID: 27471855 DOI: 10.1371/journal.pone.0155390

The role and function of the granular life cycle stage in Blastocystis sp, remains uncertain despite suggestions being made that the granules are metabolic, reproductive and lipid in nature. This present study aims to understand granular formation by triggering apoptosis in Blastocystis sp. by treating them with metronidazole (MTZ). Blastocystis sp.cultures of 4 sub-types namely 1, 2, 3 and 5 when treated with 0.01 and 0.0001 mg/ml of metronidazole (MTZ) respectively showed many of the parasites to be both viable and apoptotic (VA). Treated subtype 3 isolates exhibited the highest number of granular forms i.e. 88% (p<0.001) (0.0001 mg/ml) and 69% (p<0.01) (0.01 mg/ml) respectively at the 72 h in in vitro culture compared to other subtypes. These VA forms showed distinct granules using acridine orange (AO) and 4',6-diamino-2-phenylindole (DAPI) staining with a mean per cell ranging from 5 in ST 5 to as high as 16 in ST 3. These forms showed intact mitochondria in both viable apoptotic (VA) and viable non-apoptotic (VNA) cells with a pattern of accumulation of lipid droplets corresponding to viable cells. Granular VA forms looked ultra-structurally different with prominent presence of mitochondria-like organelle (MLO) and a changed mitochondrial trans-membrane potential with thicker membrane and a highly convoluted inner membrane than the less dense non-viable apoptotic (NVA) cells. This suggests that granular formation during apoptosis is a self-regulatory mechanism to produce higher number of viable cells in response to treatment. This study directs the need to search novel chemotherapeutic approaches by incorporating these findings when developing drugs against the emerging Blastocystis sp. infections.

Matched MeSH terms: Blastocystis/drug effects*; Blastocystis/metabolism
Viable blastocystis cysts in Scottish and Malaysian sewage samples

Suresh K, Smith HV, Tan TC

Appl Environ Microbiol, 2005 Sep;71(9):5619-20.
PMID: 16151162

Blastocystis cysts were detected in 38% (47/123) (37 Scottish, 17 Malaysian) of sewage treatment works. Fifty percent of influents (29% Scottish, 76% Malaysian) and 28% of effluents (9% Scottish, 60% Malaysian) contained viable cysts. Viable cysts, discharged in effluent, provide further evidence for the potential for waterborne transmission of Blastocystis.

Matched MeSH terms: Blastocystis Infections/parasitology; Blastocystis Infections/transmission; Blastocystis/growth & development*; Blastocystis/isolation & purification
Fulltext Subtype distribution of Blastocystis isolates in Sebha, Libya

Abdulsalam AM, Ithoi I, Al-Mekhlafi HM, Al-Mekhlafi AM, Ahmed A, Surin J

PLoS One, 2013;8(12):e84372.
PMID: 24376805 DOI: 10.1371/journal.pone.0084372

BACKGROUND: Blastocystis is a genetically diverse and a common intestinal parasite of humans with a controversial pathogenic potential. This study was carried out to identify the Blastocystis subtypes and their association with demographic and socioeconomic factors among outpatients living in Sebha city, Libya.
METHODS/FINDINGS: Blastocystis in stool samples were cultured followed by isolation, PCR amplification of a partial SSU rDNA gene, cloning, and sequencing. The DNA sequences of isolated clones showed 98.3% to 100% identity with the reference Blastocystis isolates from the Genbank. Multiple sequence alignment showed polymorphism from one to seven base substitution and/or insertion/deletion in several groups of non-identical nucleotides clones. Phylogenetic analysis revealed three assemblage subtypes (ST) with ST1 as the most prevalent (51.1%) followed by ST2 (24.4%), ST3 (17.8%) and mixed infections of two concurrent subtypes (6.7%).
BLASTOCYSTIS: ST1 infection was significantly associated with female (P = 0.009) and low educational level (P = 0.034). ST2 was also significantly associated with low educational level (P= 0.008) and ST3 with diarrhoea (P = 0.008).
CONCLUSION: Phylogenetic analysis of Libyan Blastocystis isolates identified three different subtypes; with ST1 being the predominant subtype and its infection was significantly associated with female gender and low educational level. More extensive studies are needed in order to relate each Blastocystis subtype with clinical symptoms and potential transmission sources in this community.

Matched MeSH terms: Blastocystis Infections/epidemiology*; Blastocystis/genetics*; Blastocystis/pathogenicity
Genetic diversity of caprine Blastocystis from Peninsular Malaysia

Tan TC, Tan PC, Sharma R, Sugnaseelan S, Suresh KG

Parasitol Res, 2013 Jan;112(1):85-9.
PMID: 22961236 DOI: 10.1007/s00436-012-3107-3

Blastocystis sp. is a common intestinal parasite found in humans and animals. The possibility of zoonotic transmission to humans from livestock especially goats led us to investigate the genetic diversity of caprine Blastocystis sp. obtained from five different farms in Peninsular Malaysia. Moreover, there is a lack of information on the prevalence as well as genetic diversity of Blastocystis sp. in goat worldwide. Results showed that 73/236 (30.9 %) of the goats were found to be positive for Blastocystis infection. The most predominant Blastocystis sp. subtype was ST1 (60.3 %) followed by ST7 (41.1 %), ST6 (41.1 %), and ST3 (11.0 %) when amplified by PCR using sequenced-tagged site (STS) primers. Four farms had goats infected only with ST1 whereas the fifth showed mixed infections with multiple STs. The proximity of the fifth farm to human dwellings, nearby domesticated animals and grass land as opposed to a sterile captive environment in the first four farms may account for the multiple STs seen in the fifth farm. Since ST1, ST3, ST6 and ST 7 were previously reported in human infection worldwide in particular Malaysia, the potential of the zoonotic transmission of blastocystosis should not be disregarded. The implications of different farm management systems on the distribution of Blastocystis sp. STs are discussed.

Matched MeSH terms: Blastocystis Infections/epidemiology; Blastocystis Infections/parasitology; Blastocystis Infections/veterinary*; Blastocystis/classification*; Blastocystis/genetics*; Blastocystis/isolation & purification
Predominance of Blastocystis sp. subtype 4 in rural communities, Nepal

Lee IL, Tan TC, Tan PC, Nanthiney DR, Biraj MK, Surendra KM, et al.

Parasitol Res, 2012 Apr;110(4):1553-62.
PMID: 22076050 DOI: 10.1007/s00436-011-2665-0

Blastocystis sp. is a common intestinal parasite. To date, there have been sporadic and scanty studies on Blastocystis sp. carried out in rural communities in Nepal. We surveyed the prevalence of Blastocystis sp. and its possible associated risk factors, and reported the predominant Blastocystis sp. subtype in two rural communities, Bolde Phediche and Bahunipati, in Nepal. Human faecal samples were collected from 241 participants, cultured using in vitro cultivation and examined for Blastocystis sp. The presence of Blastocystis sp. in faecal samples was further confirmed by polymerase chain reaction (PCR) and subsequently genotyped using subtype-specific sequence tagged site (STS) primers. There were 26.1% (63/241) of the participants that were infected by Blastocystis sp. We detected 84.1% (53/63) of Blastocystis sp. subtype 4 infections in these rural communities. The unusually high prevalence of Blastocystis sp. subtype 4 can be attributed to the rearing of family-owned animals in barns built close to their houses. Eighty one percent (51/63) of the Blastocystis sp. infected participants drank not boiled or unfiltered water. The present study revealed that Blastocystis sp. could pose a health concern to the communities and travellers to the hilly area in Nepal. Infection may be transmitted through human-to-human, zoonotic and waterborne transmissions. We provide recommendations to ensure good public health practices.

Matched MeSH terms: Blastocystis Infections/epidemiology*; Blastocystis Infections/parasitology*; Blastocystis/isolation & purification*; Blastocystis/parasitology*
Genetic variability of Blastocystis sp. isolates obtained from cancer and HIV/AIDS patients

Tan TC, Ong SC, Suresh KG

Parasitol Res, 2009 Oct;105(5):1283-6.
PMID: 19603182 DOI: 10.1007/s00436-009-1551-5

This represents the first study to determine the genetic diversity of Blastocystis sp. among cancer and HIV/AIDS patients. Forty Blastocystis sp. isolates obtained from 20 cancer and 20 HIV/AIDS patients were genotyped by PCR using seven pairs of known sequenced-tagged site primers. Out of the 40 isolates, 38 were identified as one of the known genotypes and two isolates were negative with all the STS primers. Blastocystis sp. subtype 3 which is reported to be associated with disease was found to be predominant among the study subjects.

Matched MeSH terms: Blastocystis Infections/parasitology*; Blastocystis/classification*; Blastocystis/genetics; Blastocystis/isolation & purification*
Evidence of plasmotomy in Blastocystis hominis

Tan TC, Suresh KG

Parasitol Res, 2007 Nov;101(6):1521-5.
PMID: 17701428

Blastocystis hominis has been regarded as an enigmatic parasite as many aspects of its basic biology remain uncertain. Many reproductive processes have been suggested for the organism; however, to date, only the binary fission has been proven. Plasmotomy is one of the modes of reproduction previously suggested to be seen in in vitro cultures. The present study provides trichrome and acridine orange staining evidence for the existence of nucleic acid suggestive of division of nucleus into multinucleate forms with the respective cytoplasm dividing giving rise to two or three progeny B. hominis. Transmission electron micrographs further confirmed that these daughter cells had respective surrounding surface coat, mitochondria, and vacuoles.

Matched MeSH terms: Blastocystis Infections/parasitology; Blastocystis hominis/physiology*; Blastocystis hominis/ultrastructure
Amoeboid form of Blastocystis hominis - a detailed ultrastructural insight

Tan TC, Suresh KG

Parasitol Res, 2006 Nov;99(6):737-42.
PMID: 16816959

The amoeboid form of Blastocystis hominis has been reported infrequently, and its morphological descriptions have yielded conflicting and confusing reports. In the present study, we used the amoeboid forms seen predominantly in symptomatic patients infected with Blastocystis to provide detailed descriptions on the fine surface structure and intracellular morphology. Scanning electron microscopy revealed the irregular shape of the amoeboid form, with an intercalated fibrillar structure and a highly convoluted surface with deep indentations and projected pseudopodia. Transmission electron microscopy showed the existence of two types of amoeboid forms of B. hominis in in vitro culture, one with a large central vacuole containing tiny electron-dense particles while the other contains multiple small vacuoles in the cytoplasm. A surface coat with varying thickness surrounded the amoeboid form, which also showed prominent, extended pseudopodia of varying shape. Irregularly shaped mitochondrion-like organelles with prominent cristae, lipid inclusions, and multiple vacuoles were frequently seen in close proximity with the pseudopodia. The characteristic nucleus with a crescentic band of electron-dense chromatin material was also seen.

Matched MeSH terms: Blastocystis Infections/parasitology*; Blastocystis hominis/ultrastructure*
Predominance of amoeboid forms of Blastocystis hominis in isolates from symptomatic patients

Tan TC, Suresh KG

Parasitol Res, 2006 Feb;98(3):189-93.
PMID: 16323025

Blastocystis hominis is one of the most common human parasites that inhabit the intestinal tract. Conflicting reports continue to exist regarding the existence and the functional role of the amoeboid forms in the life cycle of the parasite. The present study investigates the presence of these forms in 20 isolates obtained from ten symptomatic and asymptomatic patients respectively. A total of 10,000 parasite cells per ml from each isolate were inoculated into three culture tubes each containing 3 ml of Jones' medium supplemented with 10% horse serum, incubated at 37 degrees C. The contents were examined daily for 10 days. Irregular and polymorphic amoeboid forms with multiple extended pseudopodia were observed in all isolates from symptomatic patients, while none of the isolates from asymptomatic patients showed the presence of the amoeboid forms. The amoeboid forms were initially noted on day 2 and the percentages increased from 2% to 28%, with peak percentages from day 3 to day 6. Transmission electron microscopy revealed two types of amoeboid forms; one containing a large central vacuole completely filled with tiny electron-dense granules, and the other which revealed multiple small vacuoles within the central body. The cytoplasm contained strands of electron-dense granules resembling rough endoplasmatic reticulum, which is suggestive of active protein synthesis. The surface coat of the amoeboid form surrounding the parasite showed uneven thickness. Acridine orange stained the central body yellow and the periphery orange, indicating activity at the level of nucleic acids. The amoeboid form could either be an indicator of pathogenicity of B. hominis, or the form likely to contribute to pathogenicity and be responsible for the symptoms seen in patients.

Matched MeSH terms: Blastocystis Infections/parasitology*; Blastocystis hominis/cytology*; Blastocystis hominis/physiology*
Epitope variances demonstrated by Blastocystis sp. ST3 symptomatic and asymptomatic isolates

Sheela DS, Chandramathi S, Suresh K

Trop Biomed, 2020 Mar 01;37(1):210-217.
PMID: 33612732

Blastocystis sp. is an enteric protozoan parasite of humans and many animals. Blastocystis sp. subtype 3 (ST3) proves to be the highest frequency case in most populations around the world and it is further distinguished into symptomatic and asymptomatic isolates based on the clinical symptoms exhibited by infected individuals. Phenotypic and genotypic studies implicate the distinctiveness of this parasite which may describe its pathogenesis. However, the antigenic distinctiveness which describes the antibody mediated cell lysis of this parasite has not been explored. This study was aimed to identify the cross-reactivity and cytotoxicity effect between three isolates of symptomatic and asymptomatic Blastocystis sp. ST3 respectively. Antigen specificity and diversity of this parasite was performed by coculturing sera (10-fold dilution) obtained from mice immunised with Blastocystis sp. symptomatic and asymptomatic antigens and the respective Blastocystis sp. ST3 live cells through complement dependant cell cytotoxicity (CDC) assay. The results obtained has shown that, the sera (at 10-fold diluted concentration) from symptomatic and asymptomatic solubilised antigen immunised mice were able to specifically lyse the respective live parasites with an average percentage of 82% and 86% respectively. There were almost 50% crossreactivity observed between the three isolates of Blastocystis sp. ST3 from symptomatic and asymptomatic group proving high antigen diversity or rather low antigen specificity within the same group. However, there was only 17% cross-reactivity observed between the mice sera and parasitic cells of different groups (symptomatic vs asymptomatic isolates) suggesting high specificity between these two groups. We, for the first time have proven that through CDC analysis there were epitopes dissimilarities between Blastocystis sp. ST3 symptomatic and asymptomatic isolates which may allow the parasite to set up diverse immune modulations such as imbalanced Th1/Th2 responses in an infected host.

Matched MeSH terms: Blastocystis Infections/immunology; Blastocystis Infections/parasitology*; Blastocystis/immunology*
Phenotypic and genotypic characterisation of Blastocystis hominis isolates implicates subtype 3 as a subtype with pathogenic potential

Tan TC, Suresh KG, Smith HV

Parasitol Res, 2008 Dec;104(1):85-93.
PMID: 18795333 DOI: 10.1007/s00436-008-1163-5

Despite frequent reports on the presence of Blastocystis hominis in human intestinal tract, its pathogenicity remains a matter of intense debate. These discrepancies may be due to the varying pathogenic potential or virulence of the isolates studied. The present study represents the first to investigate both phenotypic and genotypic characteristics of B. hominis obtained from symptomatic and asymptomatic individuals. Symptomatic isolates had a significantly greater size range and lower growth rate in Jones' medium than asymptomatic isolates. The parasite cells of symptomatic isolates exhibited rougher surface topography and greater binding affinity to Canavalia ensiformis (ConA) and Helix pomatia (HPA). The present study also identifies further phenotypic characteristics, which aided in differentiating the pathogenic forms from the non-pathogenic forms of B. hominis. Blastocystis subtype 3 was found to be correlated well with the disease.

Matched MeSH terms: Blastocystis Infections/parasitology*; Blastocystis Infections/physiopathology*; Blastocystis hominis/classification*; Blastocystis hominis/genetics; Blastocystis hominis/isolation & purification; Blastocystis hominis/pathogenicity*
PCR fingerprinting of Blastocystis isolated from symptomatic and asymptomatic human hosts

Tan TC, Suresh KG, Thong KL, Smith HV

Parasitol Res, 2006 Sep;99(4):459-65.
PMID: 16628457

Genomic DNA from 16 Blastocystis hominis isolates comprising of eight asymptomatic isolates (A1-A8) and eight symptomatic isolates (S1-S8) was amplified by arbitrarily primed polymerase chain reaction (AP-PCR) using 38 arbitrary 10-mer primers. Six primers (A10, B5, C20, D1, F6, and F10) generated reproducible DNA fingerprints. AP-PCR amplification revealed similar DNA fingerprints among all symptomatic isolates (S1-S8) with common bands at 850 bp using primer A10, 920 bp using primer B5, and 1.3 kbp using primer D1. Isolates A1, A3, A4, A5, A6, and A7 showed similar DNA banding patterns and all asymptomatic isolates (A1-A8) shared a major band at 1 kbp using primer B5. Isolates A2 and A8 showed distinct DNA banding patterns that differed from the remainder of the isolates. The results of the phylogenetic analyses showed that all symptomatic isolates (S1-S8) formed a clade with >70% similarity among the isolates and which were clearly separate from asymptomatic isolates A1, A3, A4, A5, A6, and A7. Asymptomatic isolates A2 and A8 formed two distinct and separate clades. AP-PCR revealed higher genetic variability within the asymptomatic isolates than within the symptomatic isolates. The present study suggests that AP-PCR can be a valuable method for differentiating between isolates of B. hominis and our results support the hypothesis that our asymptomatic and symptomatic B. hominis isolates may represent two different strains/species with varying pathogenic potential.

Matched MeSH terms: Blastocystis Infections/diagnosis; Blastocystis Infections/microbiology*; Blastocystis hominis/classification; Blastocystis hominis/genetics; Blastocystis hominis/isolation & purification*
Fulltext Blastocystis sp. in Irritable Bowel Syndrome (IBS)--Detection in Stool Aspirates during Colonoscopy

Ragavan ND, Kumar S, Chye TT, Mahadeva S, Shiaw-Hooi H

PLoS One, 2015;10(9):e0121173.
PMID: 26375823 DOI: 10.1371/journal.pone.0121173

Blastocystis is one of the most common gut parasites found in the intestinal tract of humans and animals. Its' association with IBS is controversial, possibly as a result of irregular shedding of parasites in stool and variation in stool detection. We aimed to screen for Blastocystis in colonic stool aspirate samples in adult patients with and without IBS undergoing colonoscopy for various indications and measure the interleukin levels (IL-8, IL-3 and IL-5). In addition to standard stool culture techniques, polymerase chain reaction (PCR) techniques were employed to detect and subtype Blastocystis. All the serum samples collected were subjected for ELISA studies to measure the interleukin levels (IL-8, IL-3 and IL-5). Among 109 (IBS n = 35 and non-IBS n = 74) adults, direct stool examination and culture of colonic aspirates were initially negative for Blastocystis. However, PCR analysis detected Blastocystis in 6 (17%) IBS and 4 (5.5%) non-IBS patients. In the six positive IBS patients by PCR method, subtype 3 was shown to be the most predominant (3/6: 50%) followed by subtype 4 (2/6; 33.3%) and subtype 5 (1/6; 16.6%). IL-8 levels were significantly elevated in the IBS Blasto group and IBS group (p<0.05) compared to non-IBS and non-IBS Blasto group. The level of IL-3 in were seen to be significantly higher in than IBS Blasto group and IBS group (p<0.05) compared to non-IBS. Meanwhile, the IL-5 levels were significantly higher in IBS Blasto group (p<0.05) compared to non-IBS and non-IBS Blasto group. This study implicates that detecting Blastosystis by PCR method using colonic aspirate samples during colonoscopy, suggests that this may be a better method for sample collection due to the parasite's irregular shedding in Blastocystis-infected stools. Patients with IBS infected with parasite showed an increase in the interleukin levels demonstrate that Blastocystis does have an effect in the immune system.

Matched MeSH terms: Blastocystis/isolation & purification*; Blastocystis/physiology
Isolate resistance of Blastocystis hominis to metronidazole

Haresh K, Suresh K, Khairul Anus A, Saminathan S

Trop Med Int Health, 1999 Apr;4(4):274-7.
PMID: 10357863

Isolates of Blastocystis hominis from infected immigrant workers from Indonesia, Bangladesh and infected individuals from Singapore and Malaysia were assessed for growth pattern and degree of resistance to different concentrations of metronidazole. Viability of the cells was assessed using eosin-brillian cresyl blue which stained viable cells green and nonviable cells red. The Bangladeshi and Singaporean isolates were nonviable even at the lowest concentration of 0.01 mg/ml, whereas 40% of the initial inoculum of parasites from the Indonesian isolate at day one were still viable in cultures with 1.0 mg/ml metronidazole. The study shows that isolates of B. hominis of different geographical origin have different levels of resistance to metronidazole. The search for more effective drugs to eliminate th parasite appears inevitable, especially since surviving parasites from metronidazole cultures show greater ability to multiply in subcultures than controls.

Matched MeSH terms: Blastocystis Infections/drug therapy; Blastocystis Infections/parasitology*; Blastocystis hominis/drug effects*; Blastocystis hominis/growth & development
Small forms of Blastocystis hominis

Rajah S, Suresh K, Vennila GD, Khairul Anuar A, Saminathan R

JUMMEC, 2002;7:77-79.

Matched MeSH terms: Blastocystis hominis
In vivo encystation of Blastocystis hominis

Suresh K, Venilla GD, Tan TC, Rohela M

Parasitol Res, 2009 Jun;104(6):1373-80.
PMID: 19238443 DOI: 10.1007/s00436-009-1340-1

Blastocystis from infected stools of a person who showed chronic symptoms of abdominal discomfort and diarrhea were examined over a 6-month period, using transmission electron microscopy, for the ultrastructural changes from vacuolar to cystic stage. The study confirms the irregular shedding phenomenon of the organism previously reported, and for the first time, records sequential changes in encystation in stools collected over a time period. The study also confirms the existence of a precystic stage which has an immature cell wall consisting of a layer of a homogenous electron-dense mass surrounding the cell which acts as a intermediatory stage between the vacuolar and cystic stage.

Matched MeSH terms: Blastocystis Infections/parasitology*; Blastocystis hominis/growth & development*; Blastocystis hominis/isolation & purification; Blastocystis hominis/ultrastructure*
Fulltext Effect of Blastocystis sp. in dengue patients-Increase in the treatment cost and exacerbation of symptoms

Thergarajan G, Kumar S, Bhassu S, Omar SFBS, Rampal S

PLoS One, 2019;14(3):e0211034.
PMID: 30893309 DOI: 10.1371/journal.pone.0211034

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.

Matched MeSH terms: Blastocystis Infections/metabolism*; Blastocystis Infections/parasitology; Blastocystis/isolation & purification; Blastocystis/metabolism

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