[The distribution of intestinal parasites detected in The Dokuz Eylul University Medical Faculty Hospital between 2005 and 2008.]

A retrospective evaluation of the data from 14,246 patients with gastrointestinal complaints who presented at the parasitology laboratory of the Dokuz Eylul University Medical Faculty Hospital between January 2005 and December 2008 was carried out. Fecal samples of all patients were examined using native-Lugol and the trichrome and Kinyoun acid-fast staining method after sedimentation in fecal concentration tubes. One or more parasites were detected in 1320 (9.3%) of the patients. The distribution of the intestinal parasites was as follows: Blastocystis hominis, 689 (4.83%); nonpathogenic amoebas, 108 (21.82%); Giardia intestinalis, 320 (2.24%); Enterobius vermicularis, 23 (0.16%); Entamoeba histolytica/Entamoeba dispar, 34 (0.24%); and other rare parasites, 78 (0.54%). The results of this study emphasize the fact that intestinal parasitic infections are still an important public health problem.

Epidemiology of Blastocystis hominis and other intestinal parasites among the immigrant population in northeastern Taiwan by routine physical examination for residence approval

BACKGROUND AND PURPOSE

Blastocystis hominis has not been reported as an endemic disease in Taiwan, but high prevalence rates have been found among immigrants. Due to the increasing number of immigrants in Taiwan, B. hominis may become a public health problem in Taiwan. This study was performed to determine the prevalence of B. hominis among immigrant populations.

METHODS

Stool examination data from the Immigrant Physical Examination for Residence Approval in 2006 were examined.

RESULTS

Among the 932 immigrants from 4 countries, 188 individuals (20.2%) were infected with B. hominis. The prevalence was higher among immigrants from Southeast Asian countries (Indonesia, 26.4%; Vietnam, 20.6%; The Philippines, 19.3%) than among those from China (7.6%). Coinfection with intestinal parasites of fecal-oral transmission (Endolimax nana and Entamoeba hartmannii) was a risk factor for B. hominis infection (odds ratio, 16.9; 95% confidence interval, 6.84-43.55). No significant differences in prevalence for sex and age were observed.

CONCLUSION

To prevent local transmission and endemic spread of B. hominis, obligatory routine health screening for immigrant populations and early eradication of the infection are important policies for this high-risk group.

Subtype analysis of Blastocystis isolates from Blastocystis cyst excreting patients

To determine the distribution of Blastocystis sp. subtypes from Blastocystis cyst excreters, 1,000 fecal samples from patients suspected of enteroparasitic disease were scored for stool consistency, submitted to xenic in vitro culture (XIVC), formol ethyl acetate concentration (FECT) with subsequent isopycnic centrifugation, and polymerase chain reaction (PCR) with subtype (ST) analysis. Blastocystis was significantly more prevalent in specimens from patients with travel-associated diarrhea (15.6%) than those with persistent diarrhea (8.3%) (P = 0.005). Overall, 115 (11.5%) and 35 (3.5%) specimens were positive by XIVC and FECT, respectively. Blastocystis cysts were detected in 33 (28.7%) of the XIVC-positive specimens. A positive FECT result was associated with ST3 (P = 0.05). The presence of Blastocystis in general or Blastocystis cysts was independent of stool consistency, and no particular ST was significantly associated with cyst identification. In view of these data, the present study indicates that Blastocystis cyst formation is independent of Blastocystis sp. subtype and gastrointestinal transit time.

Genetic analysis of Blastocystis hominis isolated from symptomatic and asymptomatic human hosts in Egypt

Extensive genomic polymorphism was demonstrated among morphologically identical B. hominis isolates. A genetic diversity would be a powerful tool for identification or classification of B. hominis subtypes. In this study, 14 Egyptian B. hominis isolates were collected, 5 of them were isolated from asymptomatic people whose infections were detected during routine medical check-up and 9 were isolated from patients with gastrointestinal symptoms. Restriction fragment length polymorphism (RFLP) analysis of PCR amplified small-subunit rDNA (SSU rDNA) was used to study genetic diversity of B. hominis isolates by 3 different restriction enzymes (Hin-fI, RsaI & Sau3AI). Cluster analysis of the riboprint patterns showed 7 distinct genotypes out of 14 B. hominis isolates, 4 were previously reported riboprints and 3 were new ones. The frequency of intestinal symptoms was 64% in Blastocystis cases. Abdominal pain was the most frequent symptom 78% (7/9). There was no definite correlation between RFLP-banding pattern or genetically distinct genotypes and pathogenecity.

[The distribution of intestinal parasites among children in Denizli]

Intestinal parasitic disease appears to be an important national health problem in our country. Parasitic infection distribution is related to the socioeconomic status and environmental factors. The aim of this study was to determine the distribution of intestinal parasites among children in the 1-15 age group in the Denizli province. Parasitic infection was observed in 256 (10.2%) out of 2518 children. The highest rate of 31.4% was that of Giardia intestinalis. The rates of Enterobius vermicularis and Blastocystis hominis were found to be 29.6% and 14% respectively.

[The role of protozoan parasites in etiology of urticaria]

In order to investigate a possible link between parasites and chronic urticaria, the prevalence of intestinal protozoans in stool samples of individuals with chronic urticaria (n=55) and healthy controls (n=43) were evaluated with native lugol, formol-ethyl acetate concentration and trichrom dye, modified acid fast. In the case of Giardia intestinalis (G. intestinalis) ELISA was also used. In the study 29.1% of the patients were found to have protozoan (Blastocystis hominis + G.intestinalis) infections. On the other hand, only 11.6% of the patients in healthy group were having a protozoon infection, all of which were B. hominis. There was no statistically significant difference between the patient group and control group regarding the frequency of B. hominis presence. Also, the number of G.intestinalis positive patients were also statistically different in patient group from those of healthy controls. In patients whom were positive for protozoan infections, agent specific therapy was used. In 7 of these patients symptoms of the disease were subsided with this therapy while six continued to have relapses. Three patients had missed the control visits therefore the course of the disease was not evaluated. As a conclusion, protozoans should be considered in the etiology of chronic urticaria and stool examination should be done in these patients routinely.

Association of Blastocystis subtype 3 and 1 with patients from an Oregon community presenting with chronic gastrointestinal illness

Chronic gastrointestinal illness of unknown etiology is a significant problem in the United States. Using a real-time LightCycler PCR assay we detected Blastocystis in nine patients from a metropolitan area of Corvallis, Oregon who presented with diarrhea, abdominal pain, fatigue, joint pain, skin rash and psychiatric co-morbidity. Phylogenetic analysis identified six infections with Blastocystis sp. subtype 3, and one with subtype 1, using the standard Stensvold nomenclature. Most patients with subtype 3 had previously tested negative with conventional parasitological diagnostics, had been symptomatic for over 4 years, and reported antibiotic failure.

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.

Drinking water: a possible source of Blastocystis spp. subtype 1 infection in schoolchildren of a rural community in central Thailand

In January 2005, a survey of intestinal parasitic infections was performed in a primary school, central Thailand. Of 675 stool samples, Blastocystis was identified with a prevalence of 18.9%. Genetic characterization of Blastocystis showed subtype 1 (77.9%) and subtype 2 (22.1%). Study of the water supply in this school was performed to find the possible sources of Blastocystis. Blastocystis from one water sample was identified as subtype 1, which had a nucleotide sequence of small subunit (SSU) ribosomal RNA (rRNA) gene that was 100% identical to that of Blastocystis infected in schoolchildren. Our information supports the evidence of water-borne transmission in this population.

Protein profile and morphometry of cultured human Blastocystis hominis from children with gastroenteritis and healthy ones

A total of 180 children of age group 5-12 years old in both sexes, of whom 90 were symptomatic and negative for other parasites, rotavirus or pathogenic bacteria. Another 90 children were asymptomatic, but with B. hominis in stools. Direct smear, formaline-ethyl acetate sedimentation concentration, kinyon carbol-fuchin stain, stool culture, enzyme immunoassay, culturing, morphometric study, gel electrophoresis and experimental infection of mice were done. The results showed that the central body cysts (CB), granular and multivacuolar forms isolated from symptomatic patients were larger than those from asymptomatic ones. The CB form was common compared to other forms and isolated from 104 cases. B. hominis infection was prevalent among males rather than females (60.5% versus 39.5%). The clinical data showed that diarrhea was the most common symptom (58.9%). The infection intensity had a direct relation with illness duration. The polyacrylamide gel electrophoresis showed that isolates from symptomatic and asymptomatic patients ranged between 24-130 kDa. All isolates showed similar banding patterns. Only minor differences was in low MW (30, 50 kDa) and in high MW (118 kDa) in samples from symptomatic patients. The histopathological examination of caecum, colon and small intestine of B. hominis mice infected from symptommatic patients showed infiltration with inflammatory cells and tissue invasion by the parasite.

Clinical significance of Blastocystis hominis: experience from a medical center in northern Taiwan

BACKGROUND AND PURPOSE

Blastocystis hominis is an intestinal protozoan. The pathogenic role of this organism in human beings is still controversial and has varied among reports from different geographic areas. The purpose of this study was to determine the clinical significance of B. hominis in northern Taiwan.

METHODS

A total of 100 patients who had a positive B. hominis stool examination during the period April to December of 2001 were retrospectively identified from Taipei Veterans General Hospital. The demographic and clinical characteristics of these patients were reviewed from the medical records.

RESULTS

All of the patients were adults. Fifty nine patients had more than one underlying diseases, including malignancies. Twenty one patients presented with fever and 10 patients had gastrointestinal symptoms, including diarrhea and/or abdominal pain. However, all of the patients had other conditions that might have contributed to the clinical presentation, and they improved without specific treatment for B. hominis. Furthermore, there were no significant differences in clinical symptoms and white blood cell count between patients with malignancy or diabetes mellitus and those without. Six patients had hypereosinophilia that could not be attributed to other causes. Among 34 patients who had a further stool examination within one year, B. hominis was undetectable in 31 patients (91.2%), despite their having no specific antiprotozoal treatment.

CONCLUSIONS

The association of clinical symptoms and B. hominis could not be delineated from our study, even in immunocompromised patients. All of the patients improved without receiving any specific therapy. More studies from different areas are needed in order to delineate the clinical significance B. hominis.

[The prevalence of Microsporidium among patients given a diagnosis of cancer]

The aim of this study was to determine the frequency of Microsporidium among patients given a diagnosis of cancer. For this purpose fecal samples from 320 patients aged 23.60+/-23.00 years were examined using native-Lugol and sedimentation methods and evaluated with modified trichrome, trichrome, and calcofluor dyes. Moreover a control group of 320 non-cancer patients was set up. While 10.9% of the patient group was found to have Microsporidium, only 5.6% of the control group did. Comparison between the control and patient groups in terms of presence of Microsporidium revealed a statistically significant difference. The analysis of a possible relation between intestinal parasites and the presence of Microsporidium revealed a statistically significant correlation between Microsporidium and Blastocystis hominis (P < 0.05). The frequencies of intestinal parasites in the control group and the patient group were found to be 17.8% and 18.1%, respectively. From the findings it was concluded that presence of intestinal parasites and Microsporidium in cancer patients can cause critical problems and adversely affect the therapy. Moreover it was suggested that cancer patients should be informed about regular feces examination and protection against parasites in order to improve their life standards and protect them against parasite infections during treatment.

[The distribution of intestinal parasites and their causative factors in children]

Intestinal parasitic infection prevalence in children who had been brought to our hospital together with related factors. The study was carried out in 400 children who were chosen at random among those brought to our hospital. All stool samples were examined with nativelugol, formol-ether, Kinyon acid-fast, methods. The cellophane tape preparations and hemoglobin concentration measurement were used. Intestinal parasites found in 156 of 400 (39%) children were Giardia intestinalis (19.8%) Enterobius vermicularis (15%), Blastocystis hominis (5.8%). Socio-economic and educational level of patient's family, living in urban area, having abdominal pain, anal itching, salivation during sleep, and nasal itching had been found related with the prevalence of parasitic infection. No relationship were found in the other factors. Because WHO guidelines favor routine screening and treatment of parasitic infections of school-age children when the prevalence of parasitic infections in community exceeds 50%, all children should be evaluated for parasitic infections if they have one or more risk factors.

Cross-sectional surveys and subtype classification of human Blastocystis isolates from four epidemiological settings in China

The prevalence and geographical distribution of the intestinal protozoa Blastocystis in humans across China is unknown, and the relative importance of different subtypes has yet to be investigated. We assessed the community prevalence and relative frequencies of different Blastocystis subtypes in four epidemiological settings in China, i.e., Shanghai municipality, Yongjia county (Zhejiang province), Eryuan county, and Menghai county (both Yunnan province). Blastocystis infection was detected with the culture method, and the subtype was identified with polymerase chain reaction using a set of subtype-specific primers. The prevalence at the four study settings was 1.9, 5.9, 18.4, and 32.6%, respectively. People aged greater than or equal to 60 years had a higher prevalence in the former two settings, Shanghai and Yongjia, whereas the highest infection rate was found among individuals aged 10-17 years in the latter two settings, Eryuan and Menghai. A higher prevalence was found in men in the former two settings but in women in the latter two settings. Five different Blastocystis subtypes were identified from the 192 isolates. Subtype 3 was the predominant type, followed by subtype 1. In conclusion, the epidemiology of Blastocystis varies across China.

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

This study was conducted to clarify the prevalence of Blastocystis hominis and Strongyloides stercoralis infection in Ryukyu University Hospital, Okinawa, Japan, between January 2004 and November 2006. Stool samples collected from 3,292 patients were examined by the direct smear method, formalin-ether sedimentation method, and agar plate culture method. The prevalence rate of B. hominis and S. stercoralis infection was 1.0 and 3.4%, respectively. The prevalence rate of B. hominis infection in patients aged >80 years old was significantly higher than that in patients <80 years old (P < 0.001). The prevalence rate of S. stercoralis infection was significantly higher in patients with B. hominis infection compared with those without (P < 0.001). This study demonstrated a prevalence rate for B. hominis and S. stercoralis infection and an association between B. hominis and S. stercoralis infection in Okinawa, Japan.

[Infection by Blastocystis: a review]

Blastocystis sp. is an anaerobic unicellular micro-organism belonging to the kingdom Chromista, frequently found in the digestive tracts of humans and animals, the pathogenic role of which continues being controversial for human beings. Its genetic classification, which shows nine sub-types, some of which seem to have a role in cases with gastrointestinal symptomathology, opens a new field for research. In this article, an extensive revision is carried out which includes the historic development of the parasite, its taxonomy, epidemiology, morphology, vital cycle, as well as biochemical, cytochemical and genetic aspects, the pathogenic role in contrast with different variables which include the sub-types, quantity, response to the treatment and association with other pathogens. Finally, the clinical and therapeutic aspects are also reviewed.

Molecular epidemiology of human Blastocystis in a village in Yunnan province, China

The purpose of this study was to improve our understanding of the molecular epidemiology of human Blastocystis, focusing on 239 randomly selected individuals in a single village in Yunnan province, China. Emphasis was placed on the relative frequency of different Blastocystis subtypes and underlying risk factors. We used a cross-sectional study design, by employing a pre-tested questionnaire to obtain demographic data and behavioural risk factors, and collected faecal samples for culture and subsequent identification of Blastocystis. DNA was extracted from Blastocystis isolates and the subtypes were identified using 7 subtype-specific sequenced-tagged site (STS) primers. Overall, 78 faecal samples were Blastocystis culture-positive (32.6%, 95% confidence interval: 26.7-38.6%). The majority (n=73, 93.6%) were single infections with one of the known subtypes, whereas 2 isolates consisted of 2 concurrent subtypes. The remaining 3 isolates could not be identified with the currently known STS primers. Risk factors for a Blastocystis infection were drinking unboiled water, consumption of raw water plants and pig ownership. The consumption of raw water plants was positively associated with subtype 1 infections, and drinking unboiled water with subtype 3 infections. In conclusion, human Blastocystis was common in this village in southwest China, and different subtypes were associated with distinct transmission routes or sources of infection, and hence Blastocystis subtypes might be linked to specific environmental compartments.

Prevalence of intestinal parasites among primary schoolchildren in Derna District, Libya

The prevalence of intestinal parasites and some hygienic factors was evaluated in primary schoolchildren in Derna District. A total of 1039 stool specimens were examined by direct smear and formaline-ether concentration methods. The results showed that 31% of the children were infected with at least one or two parasites. These parasites were Giardia lamblia (12.7%), Blastocystis hominis (6.7%), Entamoeba histolytica/ Entamoeba dispar (6.6%), Entamoeba coli (3.2%), E. hartmanni (1.0%), Enterobius vermicularis (0.6%), Ascaris lumbricoides (0.1%) and Hymenolepis nana (0.1%). A significant difference was between infection rate and parent's education (P = 0.000), socio-economic status of the family (P = 0.000), family size and number of rooms in houses (P = 0.000). Also, there was a significant differences between infection rate and source of water for human consumption (P = 0.05).

Is this recently characterized gastrointestinal pathogen responsible for rising rates of inflammatory bowel disease (IBD) and IBD associated autism in Europe and the United States in the 1990s?

In 2006, a pathogenic variant of the common intestinal organism Blastocystis was discovered in patients who were experiencing chronic gastrointestinal symptoms. Most species of Blastocystis inhabit humans with no symptoms. The discovery of a pathogenic variant of Blastocystis is significant, because Blastocystis is related to Entamoeba, a similar organism with pathogenic variants that kill over 100,000 people each year. Recent research has shown that Blastocystis infections may be undetectable using existing clinical methods. Medical case reports from the Middle East, Europe, and United States suggest that infection with this variant may already be widespread and misdiagnosed as one of several functional disorders.

HYPOTHESIS

A more virulent or transmissible type of Blastocystis emerged in the Middle East in the 1980's, and was transmitted to Europe and the United States by military and more significantly vacation and business travel. The lack of adequate tests made it impossible to detect the infection. Transmission to the larger population resulted in rising inflammatory bowel disease (IBD) rates in Europe in the 1990's. The relationship between IBD and autism is explored, along with the possibility that the same pathogen causes both conditions.

SUPPORTING DATA

Serological and epidemiological findings are presented supporting the hypothesis. Blastocystis survives sewage treatment, shows low host specificity, and can be spread by many animals. Several communities which have been studied due to high autism rates are located close to rivers which receive large quantities of sewage effluent, such as South Thames (England), Olmsted County (Minnesota, USA) and many communities in Oregon (USA).

CONCLUSIONS

Scientists from other countries represent the first line of defense against emerging infectious diseases, but their publications on Blastocystis are not well known in the United States and Europe. With the publication of corroborating research by Western scientists in core scientific journals, it is hoped that an appropriate response from the public health system will be forthcoming. Investigation into the existence of infection in the groups mentioned with sensitive and specific tests should be performed. Such tests could include a serum antibody test and a Polymerase Chain Reaction test specific to the pathogenic variant.

Colony growth of Philippine isolates of Blastocystis hominis in simplified, soft agar medium

The agar-cloning technique of Blastocystis hominis has been observed in both solid and semisolid agar using Iscove's modified Dulbecco's medium. In this study, Philippine isolates of B. hominis were grown by pour-plate method in semisolid agar using Locke's solution. Inoculated plates contained 0.7% agar, 10% horse serum, and 0.1% sodium thioglycollate. Plates were incubated at 37 degrees C in a microaerophilic jar for 7-10 days. Biconvex disk-shaped colonies were seen abound at the bottom half of the medium. Colonies growing at the agar-glass interface were flat and consisted of thin layers of cells. From these colonies, large amoeboid cells were frequently seen on the periphery, whereas smaller cells were concentrated at the core. Analysis of the SSU rDNA genetically established the identity of the clones to be B. hominis. This is the first report on agar cloning of Blastocystis in a compound medium.

Characteristics of Blastocystis hominis infection in a Turkish university hospital

In order to determine characteristics of Blastocystis (B.) hominis infection; 770 individuals' stool specimens were examined both by simple and concentration techniques and stained with iodine solution and trichrome in the Parasitology Laboratory of Hacettepe University Faculty of Medicine, Turkey. Among the examined 770 specimens, B. hominis was detected in 94 (12.2%). B. hominis was the most common intestinal parasite among the study group. It was mostly detected with Dientamoeba fragilis. Among the groups the incidence of B. hominis in allergic patients was higher than controls. Among the immunosuppressed patients, B. hominis was detected significantly higher in patients who had solid tumours. Of the 48 individuals who had only B. hominis in their stool the most common symptom was abdominal pain. Concentration technique with trichrome stain was more sensitive than simple smear with lugol solution for the detection of B. hominis. Studies with more patients must be planed to understand the B. hominis infection in solid tumour patients and coexistence of B. hominis and D. fragilis.

[Evaluation of intestinal parasites in a period of four years in the coprology laboratory of a training hospital]

Parasitological examination of stool samples of 9867 individuals, submitted from both inpatient and outpatient departments to the Microbiology Department of an 800-bed Training Hospital between 1.1.2003 and 31.12.2006, revealed that 582 individuals (5.9%) were infected with intestinal parasites. Different diagnostic methods were employed in two different periods, and Blastocystis hominis, Giardia intestinalis and Entamoeba histolytica/dispar were found to be the most common parasites, respectively. Patients were predominantly male (67% (n=336) male vs. 33% (n=165) female) and aged between 15-25 years (36%). In addition, 14% (81/582) patients had multiple parasitoses. Despite being labor-intensive, parasitological examination of stool samples with necessary staining methods by experienced staff will surely help determine both the diagnosis and exact prevalence of intestinal parasitic infections in Turkey.

[Is Blastocystis hominis an opportunist agent?]

Despite its high prevalence throughout the world, major issues about Blastocystis hominis remain unresolved, including fundamental areas such as taxonomy and pathogenicity. Sequences of the SSUrRNA gene place Blastocystis in the stramenophiles. Analysis of the elongation factor 1-alpha gene, however, indicates similarity to Entamoeba histolytica. There is considerable morphological variability and karyotype diversity, and it appears that more than one species is present in humans and animals. In culture, three major forms predominate: vacuolar, granular, and ameboid. The vacuolated form (usually 10 to 30 mum) was most frequently detected in fecal specimens. The prevalence of Blastocystosis in humans appears to be higher in developing countries (30% to 50%) than in developed countries (1.5% to 10%), and has been associated with travel. B. hominis is the most common parasite isolated from stool specimens in symptomatic and asymptomatic persons in a variety of settings. Isolates resembling B. hominis have been described in a variety of mammals, birds, reptiles, and even insects. The significance of this human infection is uncertain.

Frequency of Giardia lamblia among children in Dohuk, northern Iraq

Out of 1261 stool specimens collected from children in Dohuk city, northern Iraq, the prevalence of Giardia lamblia infection was 38.5%. The highest rate of infection was in orphan care centres (48.1%) and the lowest in the paediatric hospital (31.3%). The age group 10-12 years had the highest rate (81.2%) and 7-9 years the lowest (22.9%); boys had a higher rate than girls. Some infected samples (70/486) showed double or triple infections and G. lamblia was combined with Hymenolepis nana, Blastocystis hominis, Entamoeba histolytica and Iodamoeba buetschlii.