About Blastocystis

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.

Blastocystis found in both small intestine and large intestine of pigs

A report from a research team at the from the University of Queensland, Australia has identified Blastocystis infection in both the small and large intestines of pigs.  By studying a total of 28 pigs infected with Blastocystis, the authors found that the primary types observed were Blastocystis sp. subtypes 3 and 1.  The researchers suggested that pigs may provide suitable animals models for Blastocystis infection in humans.  The full text of the study is available from PLOS-One.

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Researchers in Malaysia report high prevalence of parasitic infections in rural populations, lower prevalence in urban

A research team from Universiti Kuala Lumpur Royal College of Medicine has reviewed findings of 101 studies conducted over 42 years (1970-2013).  The team reports high levels of parasitism in rural populations, but a significant decline in urban populations over the time period.  The full text of the study is available in Tropical Biomedicine.

Blastocystis activates variety of pro-inflammatory cytokines in variety of mice cells

A research team from the National University of Singapore reports that Blastocystis antigens stimulate the production of a variety of cytokines, such as 1β (IL-1β), IL-6, and tumor necrosis factor alpha (TNF-α), in mouse intestinal explants, in mouse colitis colon, and in macrophages.  Further investigation utilizing RAW264.7 murine macrophages showed that Blastocystis treatment in RAW264.7 macrophages induced the activation of ERK, JNK, and p38, the three major groups of mammalian mitogen-activated protein (MAP) kinases that play essential roles in the expression of proinflammatory cytokines. ERK inhibition in macrophages significantly suppressed both mRNA and protein expression of IL-6 and TNF-α and mRNA expression of IL-1β.  For the full text of the study, refer to the journal Infection and Immunity

Researchers from Clermont Universite’ and Pasteur Institut publish new review on Blastocystis

Researchers from Clermont Universite’ and the Pasteur Institut have published an updated review on Blastocystis infection, genotyping, and clinical characteristics, entitled, “Blastocystis, an unrecognized parasite: an overview of pathogenesis and diagnosis”.    A full text of the review is available in Therapeutic Advances in Infectious Diseases

Blastocystis not found in household pets in Northwest USA, but found in shelter animals

In a study of 200 shelter dogs and cats, and 100 client-owned dogs and cats, researchers from Oregon State University (Oregon, USA) report that roughly 10% of shelter dogs and cats carry Blastocystis, while none of the client owned animals were found to be infected.  Dogs and cats infected with Blastocystis had similar reported rates of diarrhea as those not infected.  The full text of the study is available from PLOS-One.

Researchers in Denmark report D. fragilis and Blastocystis prevalent in both IBS patients and healthy controls

Researchers in Denmark report that roughly 50% of healthy individuals were found to be parasitized with Blastocystis or D. fragilis.  D. fragilis was detected in 35% of healthy controls vs. 23% of IBS patients, while Blastocystis was found in 22% of controls vs. 15% of IBS patients.  Surprisingly, individuals who drank bottled water, had no animals in the house, or had a higher income were more likely to be infected with Blastocystis.  For more information, refer to the NIH Pubmed abstract.

High prevalence of parasitism in Moroccan children

Researchers working with children in Morocco report an overall prevalence of parasitic infection of 51%.  Of the children positive for parasites, the most common infection was Blastocystis (64%), followed by Giardia at 20% (24% in rural areas, 16% in urban).    Researchers noted three different assemblage types of Giarida infection in the study population.  Full text available at

Extra-intestinal Blastocystis infection of liver found in immunocompromised host

Russian researchers report on the extra-intestinal infection of an immunocompromised patient, noting that large quantities of Blastocystis organisms were found in the patient’s liver.  Examination of disintegrated portions of the patients liver showed the organism through staining.  The researchers report the patient made a full recovery following treatment with antibiotics and an antifungal drug, and note that physicians should be aware of the potential for disseminated Blastocystis infection in immunocompromised hosts.  Abstract available in Pubmed online.

Blastocystis infection identified in most food animals from India

A study of cecal scrapings from 24 broiler chickens, 4 turkeys, and 1 piglet showed organisms consistent with Blastocystis in most of the animals.  Specifically all of the chickens, 3 of the 4 turkeys, and the piglet showed infections, albeit in small numbers.  Researchers suggested that the infections may not have been the cause of death in the animals, since the organisms were present in low prevalence in scrapings.  Researchers suggested that the study suggested that there may be health significance in the transmission of Blastocystis from animals to humans.  Full text in the Journal of Parasitic Diseases.