PCR-based identification of zoonotic isolates of Blastocystis from mammals and birds. (9/54)

The genotype of Blastocystis isolated from humans and animals is highly polymorphic. Therefore, it is important to compare the genotypes of Blastocystis isolates from humans and animals to determine the zoonotic potential of animal isolates. PCR-based genotype classification using known sequence-tagged site (STS) primers allows identification of zoonotic isolates of animal origin. To this end, 51 isolates from monkeys, cattle, pigs, chickens, quails and pheasants were subjected to genotype analysis using seven kinds of STS primers. Out of the 51 isolates, 39 were identified as one of the known genotypes, four showed mixed genotypes, and eight were unknown genotypes as these were negative for all STS primers. When these results were combined with previous studies on 41 isolates from animals and compared with the diversity of genotypes of 102 human Blastocystis hominis isolates, 67.4 % (62/92) of isolates from mammals and birds were identical to human B. hominis genotypes. Since the unknown genotype of human origin had been placed into an additional clade in the small-subunit rRNA gene phylogeny, further molecular study on the eight isolates of unknown genotype from the present study will facilitate our understanding of their zoonotic potential.  (+info)

Evidence of waterborne transmission of Blastocystis hominis. (10/54)

A cross-sectional study was performed in February 2001 to evaluate the prevalence and risk factors of Blastocystis hominis infection in army personnel who resided in an army base in Chonburi, Thailand. A total of 904 army personnel were enrolled in this study. Short-term in vitro cultivation was used to detect B. hominis in stool samples. In this population, B. hominis was the parasite most frequently found, and was identified in 334 of 904 stool specimens (36.9%). A significant association between B. hominis infection and symptoms was identified that might emphasize the role of B. hominis as a human pathogen. After adjustment for potential confounders, significantly increased risk of being infection with B. hominis was associated with being a private, working in a specific unit, and consuming unboiled drinking water. Thus, waterborne transmission of B. hominis infection was indicated at this army base. However, other modes of transmission cannot be ruled out.  (+info)

Epidemiological survey of Giardia spp. and Blastocystis hominis in an Argentinian rural community. (11/54)

The aim of this study was to relate personal data, socio-cultural and environmental characteristics, and the presence of symptoms/signs with the frequencies of Giardia spp. and Blastocystis hominis among a rural population in Buenos Aires Province, Argentina. Of the surveyed population (350), 3.7% were infected with only Giardia spp. or 22.9% with B. hominis, and 2.3% were infected with both protozoa. The frequency of infection according to sex; 6.1% of males were infected and 1.6% of females by Giardia spp., 26.7% and 19.5% by B. hominis, and 2.4% and 2.2% by both parasites, respectively. Giardia spp. was detected in only three adults (over 14 years), but B. hominis was more frequent in adults than in children. The prevalences of these protozoa in this community are lower than those reported by other Argentinean studies, which is probably associated with the low density of the studied population (5.95 inhab/km2). Statistical analysis revealed that a male sex, flooding of the home, the use of a latrine, and an abdominal pain were correlated with the presence of these parasites, which indicate the importance of these factors in rural communities.  (+info)

Molecular phylogenies of Blastocystis isolates from different hosts: implications for genetic diversity, identification of species, and zoonosis. (12/54)

Small-subunit (SSU) rRNA gene sequences were obtained by PCR from 12 Blastocystis isolates from humans, rats, and reptiles for which elongation factor 1alpha (EF-1alpha) gene sequences are already available. These new sequences were analyzed by the Bayesian method in a broad phylogeny including, for the first time, all Blastocystis sequences available in the databases. Phylogenetic trees identified seven well-resolved groups plus several discrete lineages that could represent newly defined clades. Comparative analysis of SSU rRNA- and EF-1alpha-based trees obtained by maximum-likelihood methods from a restricted sampling (13 isolates) revealed overall agreement between the two phylogenies. In spite of their morphological similarity, sequence divergence among Blastocystis isolates reflected considerable genetic diversity that could be correlated with the existence of potentially >/=12 different species within the genus. Based on this analysis and previous PCR-based genotype classification data, six of these major groups might consist of Blastocystis isolates from both humans and other animal hosts, confirming the low host specificity of Blastocystis. Our results also strongly suggest the existence of numerous zoonotic isolates with frequent animal-to-human and human-to-animal transmissions and of a large potential reservoir in animals for infections in humans.  (+info)

Blastocystis hominis and other intestinal parasites in a community of Pitanga City, Parana State, Brazil. (13/54)

The objective was to estimate the prevalence of Blastocystis hominis, to evaluate the effectiveness of different techniques for its diagnosis as well as to estimate the prevalence of other intestinal parasites in the community of Campo Verde, a district of Pitanga. The work was carried out from August to October 2004. Samples of feces from children and adults were collected and submitted to the techniques of direct wet mount, flotation in zinc sulphate solution, tube sedimentation, sedimentation in formalin-ether and staining by Kinyoun and iron hematoxylin methods. From 181 studied individuals, 128 (70.7%) showed protozoa and/or helminths in stool samples. The most prevalent species were Endolimax nana (33.7%); B. hominis (26.5%); Giardia lamblia (18.2%); Entamoeba coli (17.1%); Ascaris lumbricoides (16.6%); Iodamoeba butschlii (9.4%); and ancylostomatidae (7.7%). B. hominis was only identified by the techniques of direct wet mount, sedimentation in formalin-ether and staining by iron hematoxylin, though the latter was less sensitive than the other methods. The high frequency of B. hominis demonstrated by this study indicates the need to include laboratory techniques that enable identification of the parasite on a routine basis.  (+info)

Viable blastocystis cysts in Scottish and Malaysian sewage samples. (14/54)

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.  (+info)

Infection of Blastocystis hominis in primary schoolchildren from Nakhon Pathom province, Thailand. (15/54)

A study was conducted to evaluate the infection status of Blastocystis hominis in children from four public schools in Phuttamonthon district, Nakhon Pathom province, Thailand during November to December 2004. A total of 814 faecal specimens were used for B. hominis cultivation using Jones' medium. Mixed infections with other intestinal parasites were also examined by formalin ethyl acetate concentration method. It was found that 13.51% (110 of 814) of the children examined were infected with B. hominis. Mixed infections with other intestinal protozoa and helminths were observed in 10.91% (12 of 110) of B. hominis positive specimens. There were Giardia lamblia cysts (4.55%), Trichomonas hominis trophozoites (1.82%), Entamoeba histolytica cysts (0.91%), Endolimax nana cysts (0.91%), Strongyloides stercoralis larvae (0.91%), hookworm eggs (0.91%), and Trichuris trichiura eggs (0.91%). Of the children positive for B. hominis, there was no significant differences between sex (P > 0.05) and showed no correlation between age and the percentage of infection. The different infection rates among four schools indicated the involvement of hygienic factors which promoted the infection of this common intestinal protozoan. Variation in size of B. hominis was found in culture medium, which might indicate to the presence of different strains of B. hominis infection.  (+info)

Pathogenicity of Blastocystis hominis, a clinical reevaluation. (16/54)

Blastocystis (B.) hominis was considered to be a member of normal intestinal flora in the past, but in recent years it has been accepted as a very controversial pathogenic protozoan. In this study, 52 individuals whose stool examination revealed B. hominis were evaluated for clinical symptoms. Metronidazole was administered for 2 weeks to the patients infected with B. hominis. After 2 weeks of treatment they were called for a follow-up stool examination. No other bacteriological and parasitological agents were found during stool examination of these patients. The frequency rate of intestinal symptoms was 88.4% in the B. hominis cases. Abdominal pain was the most frequent symptom (76.9%). Diarrhea and distention followed at a rate of 50.0% and 32.6%. Intestinal symptoms may be seen frequently together with the presence of B. hominis and this protozoan may be regarded as an intestinal pathogen, especially when other agents are eliminated.  (+info)