Blastocystis is a highly prevalent single-celled parasite that infects the gastrointestinal tract of humans and animals. It has become the most prevalent gastrointestinal parasitic infection in developed and many developing countries, and it will produce long-term diarrhea, abdominal pain, and other symptoms in healthy individuals.
BRF’s web site has written and audio descriptions from patients, information on the newest research in diagnosis and treatment of Blastocystis ’hominis’ infection, and information on BRF”s advocacy program.
Researchers evaluating a triple-antibiotic therapy for treatment of Blastocystis infection report the results of a trial with 10 patients. Blastocystis carriage was evaluated both by stool culture and RT-PCR Testing. Of the 10 patients studied, 6 reported clearance at 6 weeks. All patients (n=2) reporting dramatic clinical improvement (>4 points) cleared the organism, and both were multiply infection with ST3 and ST4. The remaining 4 patients who reported clearance had varying degrees of non-statistically significant improvement, while some of the patients who did not clear the organism also reported improvement. A significant proportion of patients studied reported low IgA levels. A full text of the study is available in Gut Pathogens.
Researchers studyng fecal samples collected at random from 382 children age 2-15 years report that 93% of the samples tested positive for at least one parasitic infection. Females were more likely to present with multiple parasitic infections (85.4%, 326/382, p=0.001). Rural background and age status (6-11) were also positively associated with infection probability, as were drinking river water. Walking barefoot was positively associated with hookworm infection. Abstract available at NIH Pubmed server.
Researchers used fecal samples and post code information from patients at four public hospitals in Sydney to determine that Blastocystis infection is more likely to occur in certain geographic regions. A total of 910 records were examined for patients seen from 2007-2010, and 580 cases with post code data were examined. Blastocystis was found in 57% of the samples, Giardia in 27%, and D. fragailis in 12%. Age prevalnece decreased up to age 24, but increased from age 25 onward. The full text text of the paper is available in the Journal of Public Health Research.
Researchers studying Blastocystis isolated from animal cadavers in Channai, India report that scrapings from cecal sections, but not duodenal sections, are a reliable method for identifying Blastocystis infection. Of 24 animals found positive for Blastocystis, cecal scrapings were positive in all cases, but duodenal scrapings were positive in only 6 cases. The full text of the paper is available from the Journal of Parasitological Infections.
Researchers at the National Taiwan University report on a case history of a 34-year old Filipino man who developed heart failure following heart valve surgery. The heart failure was followed by persistent diarrhea and sepsis. Infectious disease testing, which included testing for viruses, E. histolytica, and C. diff failed to identify any pathogen other than Blastocystis. Symptoms resolved following treatment with metronidazole. The paper was published in the International Journal of Surgical Case Reports.
Blastocystis has at times been called a non-pathogenic yeast, so researchers at the University of Singapore put that claim to the test, by comparing the response of Blastocystis to the intestinal yeast Saccharomyces Boulardi. Their study reports that exposure of intestinal samples from mice to Blastocystis produces a significant amount of up-regulation of inflammatory chemicals, including interleukin 1β (IL-1β), IL-6, and tumor necrosis factor alpha (TNF-α). The study found that production of the inflammatory factors in macrophages was caused primarily by up-regulation of factor ERK in cells, as inhibition of ERK significantly suppressed both mRNA and protein expression of IL-6 and TNF-α and mRNA expression of IL-1β. Exposure of cells to Saccharomyces Boulardi did not produce that effect. The study also examined experimental animal infection with Blastocystis sp. subtype 7 on mice, and found increased rate of inflammation, but that was not statistically significant [in contrast to earlier study by El-Wakil]. The researchers suggested that pre-treatment of mice with Dextran Sulfate, which was intended to emphasize potential Blastocystis pathology, may have negated the effect of Blastocystis. The study was published in Infection and Immunity.
A study of Blastocystis in a commercial pig herd and an immunosuppressed research herd shows a high prevalence of Blastocystis sp. subtype 5 in those groups. The researchers report that this particular species is likely host-adapted to pigs. Examination of intestinal biopsies from the pigs show no apparent signs of pathology or invasiveness, with Blastocystis cells appearing on the surface of the intestines in samples examples. The study was published in PLOS-One.
A study of Blastocystis infection in the Irish using sensitive DNA analysis techniques shows an overall prevalence of 56% in a point-prevalence study of 105 asymptomatic individuals. A separate smaller study tracked Blastocystis infection in 5 asymptomatic and showed the presence and subtype of infection remained consistent over at least 5 years. The study was published in FEMS Microbiology Ecology.
Researchers in Turkey studying results from examination of 111,889 stool samples report an overall prevalence of 5% (5486/111,889) in stool samples examined. The majority of positive samples showed Giardia, with Ascaris lumbricoides, and Blastocystis hominis: 16%, 7%, and 6%, respectively. Between 2000 and 2012, a highly significant reduction in general parasite prevalence was determined, compared to the 1988 and 2000 time period (p<0.001). The study was published in the Turkish Journal of Parasitology.
For many first world travelers, a trip to the tropics ends in diarrhea, which can be challenging for physicians to diagnose, due to the large number of organisms that can cause that illness. Researchers in Switzerland report some success with the use of a multiplex nucleic acid test in identifying pathogens in returning travelers, both adults and children. Although the multiplex test did not cover Blastocystis, results suggest that this might be an appropriate addition to the assay. The test was more successful at identifying pathogens in children, with 52% of samples from children showing positives, with rotavirus being the most common at 27%. Adult samples were positive only 11% of the time, but a separate microscopic examination showed Blastocystis infection in 23% of those individuals. The study was published in the journal Infection.