Blastocystis hominis. Is It Really A Problem?

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Blastocystis hominis cyst-like forms in a wet mount stained in iodine
Blastocystis hominis cyst-like forms in a wet mount stained in iodine


Michael E. Ash BSc (Hons) DO. ND. F.Dip ION reviews the latest studies on this pathogen.

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 the understanding of Blastocystis biology.

Despite years of study, the pathogenic role of Blastocytis hominis is still regarded by some as controversial. It is thought that establishing relevant genotypic differences between the asymptomatic and symptomatic isolates should assist in determining the pathogenicity of Blastocystis by clearly assigning symptoms to genotype.

In a recent study, the researcher’s genotyped 32 Blastocystis isolates obtained from 12 asymptomatic healthy individuals and 20 symptomatic patients. They used polymerase chain reaction techniques to identify the known seven kinds of sequence tagged subtype primers. When they compared genotype of Blastocystis isolates between the symptomatic and asymptomatic patient group, they found that subtype 3 is the most dominant genotype in asymptomatic individual (9/12) and subtype 1 determined all of symptomatic patients (20/20).[1] Suggesting that variations in the genetic makeup can have significant impact on the likelihood of an individual experiencing symptoms.


This genetic investigation is not undertaken by standard pathology labs. If it was more readily available, B.hominis spp subtypes, known to be of ‘nil’ pathogenicity could be either ignored or treated prospectively. Patients who in the past have been treated and shown benefit on elimination of B.hominis most likely were infected with the species that met the genetic requirements for pathogenic response, and those treated but post eradication had no improvement may have had other confounding pathogens or underlying health problems.

New Insights on Classification, Identification, and Clinical Relevance of Blastocystis spp

Further clarification of this ubiquitous organism can be found in the excellent free review by Kevin Tan: Clinical Microbiology Reviews; published in Oct. 2008.[2]

The image below is extracted from the article and simplifies a model for pathogenesis of Blastocystis spp. It shows how Blastocystis infection may result in a variety of pathological outcomes such as secretory IgA degradation, barrier function compromise, host cell apoptosis, and induction of proinflammatory cytokines.

SIgA degradation and barrier disruption may promote the growth and invasion of local gastrointestinal pathogens or the expansion of commensal organisms, that by virtue of their different ratio become problematic. This can explain the apparent dysbiosis found in patients with B.hominis confirmed. The degradation of SIgA also contributes to loss of bacterial balance and will reduce the competence of regulatory T Cells (Treg) production which in turn may increase the risk of proinflammatory related para-inflammation local to the gut and systemically.

GM-CSF, granulocyte-macrophage colony-stimulating factor.


Clinical features of illness that have been attributed to Blastocystis spp. are nonspecific and include nausea, anorexia, abdominal pain, bloating, flatulence, and acute or chronic diarrhoea. Of these features, the most commonly recorded symptoms among patients are abdominal pain and diarrhoea.[3] Symptoms can be variable, ranging from mild diarrheal illness[4] and chronic diarrhoea[5] to acute gastroenteritis.[6]

One study has described an association between infection density and allergic cutaneous diseases. In a study of Blastocystis-positive patients from a Turkish hospital, the criteria for selection were the absence of any other co-infecting pathogens and the presence of more than five parasites per high-power field. The symptoms from this group were abdominal pain (76.9%), diarrhoea (50%), distension (32.6%), and urticaria (5.7%), suggesting an association between parasite density and pathology.[7] Other signs and symptoms associated with Blastocystis infections include faecal leukocytes, eosinophilia, and cutaneous rashes, particularly urticaria.[8],[9],[10]

Accumulating reports also suggest an association between Blastocystis and irritable bowel syndrome (IBS), a functional bowel disorder in which abdominal pain is associated with a defect or a change in bowel habits.[11] In two studies[12],[13]Blastocystis was detected more frequently in IBS patients than in a control group consisting of IBS-negative patients with gastrointestinal symptoms.


This is a more controversial area, as the use of Metronizadole (Flagyl) is often the first recommended intervention but can be ineffective. The cyst form has been shown to be resistant (up to 5 mg/ml) to the cytotoxic effect of the drug.

Those observations, together with the extensive genetic heterogeneity of the organism, may offer explanations for the variability in drug susceptibilities and treatment failures. A summary list of drug interventions may be found in the Tan article.

Studies to investigate the usefulness of cotrimoxazole in Blastocystis infections and Nitazoxanide, a 5-nitrothiazole broad-spectrum antiparasitic agent, have been reported to be effective against Blastocystis.

Paromomycin, a broad-spectrum antibiotic indicated for acute and chronic intestinal amoebiasis, was shown to successfully treat Blastocystis infections associated with cutaneous lesions, predominantly urticaria.

Iodoquinol has been suggested to be a suitable eradicator of this organsim. Metronidazole, iodoquinol, or co-trimoxazole has been reported to be effective in Blastocystis infections, but metronidazole resistance may be common.

Natural Strategies

  1. Establish support for SIgA production using Saccharomyces Boulardii, also prescribe with any antibiotic therapy to reduce loss of commensals. SB also inhibits IL-8 and reduces inflammation
  2. Introduce a natural antimicrobial, this can include, standardised oil of oregano, black walnut, artemesinin, berberine sulphate, citrus seed extract.
  3. Restoring the microbial ecology with the use of suitable probiotics and immune supporting nutrients especially Vit A for the modification of Treg activity and glutamine for barrier integrity.

Treatment may not be required if the B.hominis is not of the pathogenic type, other agents may be causing the symptoms. The use of medications may be judged by the severity of the symptoms and prior use. The long term success of eradication will depend on the successful restoration of mucosal immune function and the continued non exposure to repeat infection.


[1] Eroglu F, Genc A, Elgun G, & Koltas IS (2009). Identification of Blastocystis hominis isolates from asymptomatic and symptomatic patients by PCR. Parasitology research, 105 (6), 1589-92 PMID: 19685075

[2] Tan, K. (2008). New Insights on Classification, Identification, and Clinical Relevance of Blastocystis spp. Clinical Microbiology Reviews, 21 (4), 639-665 DOI: 10.1128/CMR.00022-08

[3] El-Shazly, A. M., A. A. Abdel-Magied, S. N. El-Beshbishi, H. A. El-Nahas, M. A. Fouad, and M. S. Monib. 2005. Blastocystis hominis among symptomatic and asymptomatic individuals in Talkha Center, Dakahlia Governorate, Egypt. J. Egypt. Soc. Parasitol. 35:653-666. View Abstract

[4] Rossignol, J. F., S. M. Kabil, M. Said, H. Samir, and A. M. Younis. 2005. Effect of nitazoxanide in persistent diarrhea and enteritis associated with Blastocystis hominis. Clin. Gastroenterol. Hepatol. 3:987-991  View Abstract

[5] Rossignol, J. F., S. M. Kabil, M. Said, H. Samir, and A. M. Younis. 2005. Effect of nitazoxanide in persistent diarrhea and enteritis associated with Blastocystis hominis. Clin. Gastroenterol. Hepatol. 3:987-991  View Abstract

[6] Andiran, N., Z. C. Acikgoz, S. Turkay, and F. Andiran. 2006. Blastocystis hominis—an emerging and imitating cause of acute abdomen in children. J. Pediatr. Surg. 41:1489-1491. View Abstract

[7] Kaya, S., E. S. Cetin, B. C. Aridogan, S. Arikan, and M. Demirci. 2007. Pathogenicity of Blastocystis hominis, a clinical reevaluation. Turkiye Parazitol. Derg. 31:184-187. View Abstract

[8] Diaczok, B. J., and J. Rival. 1987. Diarrhea due to Blastocystis hominis: an old organism revisited. South. Med. J. 80:931-932. View Abstract

[9] Garavelli, P. L. 1991. The therapy of blastocystosis. J. Chemother. 3(Suppl. 1):245-246. View Abstract

[10] Armentia, A., J. Mendez, A. Gomez, E. Sanchis, A. Fernandez, R. de la Fuente, and P. Sanchez. 1993. Urticaria by Blastocystis hominis. Successful treatment with paromomycin. Allergol. Immunopathol. (Madrid) 21:149-151

[11] Giacometti, A., O. Cirioni, A. Fiorentini, M. Fortuna, and G. Scalise. 1999. Irritable bowel syndrome in patients with Blastocystis hominis infection. Eur. J. Clin. Microbiol. Infect. Dis. 18:436-439. View Abstract

[12] Giacometti, A., O. Cirioni, A. Fiorentini, M. Fortuna, and G. Scalise. 1999. Irritable bowel syndrome in patients with Blastocystis hominis infection. Eur. J. Clin. Microbiol. Infect. Dis. 18:436-439. View Abstract

[13] Govind, S. K., A. A. Khairul, and H. V. Smith. 2002. Multiple reproductive processes in Blastocystis. Trends Parasitol. 18:528. View Abstract

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121 Comments. Leave new

  • Many thanks for your helpful response!

  • Hello Michael

    Can you please tell me if fermented vegies are safe to eat if I have blasto? I’ve heard that they have a lot of latic acid which isn’t good to consume. Do you think that the good bacteria in fermented foods actually survives the acid of the stomach to recolonise in the SI? Do fermented veggies chelate heavy metals? And finally what are your thoughts on colonics?

    thank you for sharing your knowledge.

  • Hello Michael,

    Can you recommend a lab in London where one can have the tests for B. Hominis and D. Fragilis?


  • Hi Michael,

    This post is wonderful and is a clear indicaton of the depth of your knowledge. I understand that you cannot give personal suggestions, but wanted to see if you can relate my sysmptoms to this protozoan.
    Brief history. I am originally from India and my stoamch issues started at around 25 yrs an yr after I landed in US. It started with abdominal pain. Major tests endo, colonoscopy, Barium, CT’s and after all that a breath test for H Pylori which was positive and treated with Prev Pac.

    That resolved the pain to a managable load but not completely gone. I was not aware at that time that we needed to retest to see if H Pylori was gone and neither my primary care doctor who treated me bothered.The pain continued and i strated seeing a GI who thought a stomach infection (I had loose stool early in the morning with an urgency) and treated me with Rifaximin and a month long Erithromycin. No significant improvement.Anyway I had a preganancy(unplanned) and went ahead with it. Had stomach issues on and Off for 2 more yrs and then another GI decided to repeat the Endoscopy and Colonoscopy and found H pylori and gastritis. and was prescribed antibiotics.I was scared to do the second round because of the terrible side effects.I waited for like an year , tried some natural remedies in between and finally strange symptoms started: Loose stools in the morning with an urgency(kind of like you cannot stop),
    massive churning and kind of bubbling feeling around 2-3 am every morning causing sleep deprivation, massive bloating, and belching like 40 times a day and rectal Itching(I was sure I had a parasite) B12 deficiancy, anemia and several vitamin Deficiencies.Regular O & P came back negative. I started on 2nd round of antibiotics Flagyl and tetracycline combo. On day 4 of the antibiotics my stool started firming up and I felt that there was a complete evacuation for the first time as far as I can remember. That’s it I thought the antibiotics are working, althought the bloating got worse and burping didn’t improve. As a side effect I started with Reflux symptoms. After a week after I completed the antibiotics, the same thing started again loose stools and this time even with a vengeance, very loud intestinal gurgling, massive bloating and belching. I was researching and found SIBO could cause Bloating, brought this up with my GI and he dismissed it completely and mentioned that even if it was SIBo then the Flagyl and tetracycline Combo would have taken care of it. And about the gas, try a diet which does not give gas(which I was already on for a last couple months, No gluten, no sugar, no fruits). I have also contacted some doctors in India and most of them feel that H Pylori is very common in India and may not cause all of my symptoms..

    Back to researching and found out about Blasto and was wondering if my symptoms connect to it. I am still trying to find a person who can rder the metametrix stool test for me.

    Lastly I wanted to add that my son who is 5 developed similar symptoms recently (Bloating, burping and indigestion) and it breaks my heart to see him go through what I have gone through at this tender age. He tested negative for H Pylori(thru stool test).I am in tears everyday seeing his condition(like a pregnant belly). I dewormed him with mebendazole with his pediatricians advice.Nothing helped.

    Two memebers in the family developing similar symptoms might not be SIBO, but then again I cannot be sure.I always think H Pylori is there, but there is also something missing that is not yet found(Could Blasto be the possibility)

    I would appreciate your thoughts. Also I think the weak immune system might be a biggie in our issues.Is there anything that we can add to improve our immune system

    I started my son the Culturelle probiotics LGG this week.Waiting for a miracle to happen in our lives

    • Dzenana Tahmiscic
      June 30, 2023 6:09 am

      Omg I just read your post, I realky hope you can see this. We all also have symptoms… my symptoms started first , burping oily stool loose, loud stomach sounds, did all the major investigations, nothing, diagnosed with fat malpsorption,.. , then my husband he had the same symptoms , then the worst happened my kids started losing weight, started burping , having loud stomach sounds. We all tested for parasite and they found Blasto with my husband, i am so scared for my kids, My husband and I tried metranidazole and it did not help.,..Doctors don’t know how to help, I really hope you see this and tgst you can help how your situation resolved. I also tried rifaximin and tons of other stuff….

      • Leah Jamieson
        June 30, 2023 8:49 am

        Hi, Dzenana, I have emailed you, please check your spam folders if not received. Best Wishes, Leah

  • Hello Michael

    Can you please tell me how SIBO occurs and also if cultured veggies are beneficial for Blasto. I’ve heard that cultured veggies contain lactic acid and this is not good for SIBO, can you enlighten us more on this subject.

    thank you

    • Hi
      Small Intestinal Bacterial Overgrowth (SIBO) Small intestine bacterial overgrowth (SIBO) is characterised by the increase in number and/or type of colonic bacteria in the upper gastrointestinal tract. It is defined as the finding of more than 105 Colony Forming Units (CFU/mL) in the upper small intestine or 103 CFU/mL if isolated bacteria are typical from large intestine. Symptoms of SIBO include abdominal pain, bloating, flatulence, and diarrhoea, similar to those observed in patients with IBS.
      Causes include, medications such as proton pump inhibitors, antibiotics, comorbidities such as dyspepsia, post-surgery or ileocecal valve dysfunction, but its actual pathogenesis is not completely understood.

      Cultured vegetables comprise part of an historical diet that mostly increases the presence of bacteria in the food. In terms of would that impact B.h beneficially, there are no papers on this, but in principle it should be benign.
      In terms of SIBO, increasing methane through bacterial feeding can occur with vegetable intake and may conceivably be exaggerated with fermented food. Again there are no studies so I am making a reasoned assumption.

  • Hi Michael,
    Thanks for all the great information.
    I’m wondering if you might have any more information on the connection between four fecal body odors (and other body doors) and parasite or yeast infections. I write a blog on this problem and would love to hear your opinions on the matter. Our community has even had suicides from this problem as people’s social lives become so disrupted.

    Nobody seems to have any answers. I was found by a Gastro doctor to have a bacteria problem but was never told what specific one. I was also found to be lactose and sucrose intolerant through a bowel biopsy. He rotated me on 3 or 4 different antibiotics for 6 months or so, but the problem while improving, still occurred. He also put me on Creon digestive enzymes, probiotics, thiamine, folic acid, b-12 injections and a few other things. My blood results have improved. My blood sugars no longer dive during the 2 hour blood glucose
    test now. So there have been some improvements. Alternative tests have indicated I have a bunch of different parasites, but of course the gastro doctor does not take these tests serious. Any help is appreciated by our community.

  • Dear Mr. Ash,

    Can Blastocystis hominis only affect the upper GI tract (i.e. causing problems otherwise described as “functional dyspepsia”, such as post-prandial fullness, belching, gastroparesis) and not affect the lower GI tract?

    Or is it possible that the parasite would, as you have described, affected the intestinal walls, hence creating multiple food intolerances, which in turn would cause the functional dyspepsia symptoms? I seem to have none of the lower GI tract symptoms, only the upper ones. Intolerances to milk, grains and egg whites were discovered, in addition to the B-hom infestation, but I am not sure which one comes first or needs to be addressed in priority.

    I also wonder if it is possible to harbour the parasite for years (perhaps 20 years) and only experience symptoms later in life. I have travelled to South America 20 years ago, was very sick over there (with what is qualified as “alarm symptoms”), but healed… until 2 years ago, but as described above, I only have upper GI tract issues. The gastroparesis being the most distressing one. In my case, the initial onset of the symptoms followed an operation.

    Finally, have you heard of successful stories of b-hom treatment involving metoclopramide? I did a one month course of this medicine and was “healed” for several months last year until the symptoms started again, following “abuse” of bread in France… This parasite definitely thrives on carbs.

    Thank you very much for your comments, I have not read someone as knowledgeable and generous as you in my research!


  • Hi Michael
    Thank you so much for such detailed information and advice.

    I completed a stool test with large amounts of b hominis and endolimax nana. There was a small candida overgrowth as well as large amounts of gram negative koaria kristinae and (non pathogenic) ecoli in respect to medium amounts of gram positive bacteria. There was no evidence of inflammation. Sig A was very low at 12.

    I have been alternating herbal treaments including a sweet wormwood in capsule form and a herbal tincture (including wormwood, peppermint) alongside a berberine and grapefruit seed in capsule form. I have also been taking serrapeptase enzyme (away from food).

    I started this protocol in April and have just started taking probiotics, glutamine and saccaromyces.

    Since May I’ve also cut out grains, dairy and sugar (not fruit or zylitol) nearly completely.

    Then because I was feeling physically tired I cut the supplements out for a week and my symptoms (loose bowel movements / fatigue, anal itching, poor sleep, some cramping) returned in a week. I’ve since resumed the protocol and included the probiotics/glutamine and saccaromyces.

    I wondered if you are aware of any specific treatment for endolimax nana because no-one seems to have heard of it?
    I also wanted to check if oregano oil is useful for parasites because I thought it was more for fungal overgrowth.

    I wondered if additional vitamin A (alongside the amount in a multi) would be useful to support low sig A alongside saccaromyces?

    I am reluctant to consider anti-biotics/ GP treatment. However I also don’t want to indefinately continue this protocol. Are you aware of any specialist doctors for prescribing medication rather than simply metronidazole and do you recommend any specific herbal supplements?

    Thank you very much.

  • Hi
    Sorry, one further question, is it useful to take FOS to build up beneficial bacteria with a parasite infection or will the FOS simply be used by the parasite?

  • Hi Michael

    I have been informed that my 14 week old daughter has blastocystis hominis present in her faeces, I am extremely worried about this as she is so small. She is a very unsettled baby and cries often, do you think it’s because of this and is it something that will clear on its own?

    Kind regards

  • Dear Michael

    Ive been suffering for four years with Blastocystis hominus. Im clean for almost three years.

    But for the last week the systems are all back.

    Is it possible that the parasite can stay dormant?

    Kind Regards


  • Can you please explain the links if any between blastocystis hominis and functional dyspepsia? I was diagnosed with “many” bh. This is the only thing in all the tests that I have done, that would explain the functional dyspepsia that I have been suffering for 2 years (onset at 38 years old). I took a herbal protocole, along with dietery restriction, and then metrodinazole, but my symptoms are still there: mainly postprandial fullness and excessive belching and not being able to digest wheat (although no lower GI tract sympots whatsoever). Is the functional dyspepsia the result of the many bh? Are they related via the alteration of gastric juices and movements? Or is it only a coincidence? The only other explanation for my problem is so-called “perimenopause” — but that seems far fetched… Thank you for your help, I would be most grateful for an answer.

  • Hello Michael
    I just wanted to ask about soluble fibre, and if I can use raw grated carrots instead of grated apples? I don’t do well with apples as they give me bloating. Do you think carrots would have the same effect?

    thank you again for a wonderful article and exchange of information. Your recommendations to heal and the gut lining is so important. It reminds me of Pasteur’s famous last words, “the germ is nothing, the terrain is everything”.

  • Hello Michael, At last I found your article after cruising for information for both Blastocystis and Candida. I am off all sugar so i am leary to eat so many apples a day. Would you suggest green apples (not quite ripe as opposed to the color) to prevent consumption of sugar which tends to set off symptoms again? Also, I am so glad to understand the need to separate the anitmicrobials from food. I have been taking them just before my meals for a few weeks and it hasn’t been pretty.
    Thanks again. I look forward to returning to this site for what has been an 18 month long struggle.
    Any thoughts on if saunas or steambaths help the body with eradication? ali

  • Hello Michael.

    I have learned so much reading the article and entire comment thread. I appreciate your diligence in answering every comment here. I was first diagnosed with Blastocystis in 2011 and since then have worked with four different doctors (in two different states), and put in multiple hours of my own research. I have also tried two different treatment strategies (self directed herbal protocol, Dr. directed Alinia protocol) – yet still test positive for Blasto, and still have the symptoms I began with. Throughout all of this, nowhere have I found information as thorough and detailed as what you present here.

    In my case, I have almost no gastro-intestinal symptoms. Sometimes I bloat up, but I can avoid this if I am careful about what I eat. My bowel movements are healthy and regular.

    My primary symptom of digestive distress is a long list of food intolerances – a list that began with wheat in about 2009 and since then has slowly, yet surely, grown to include an intolerance to: dairy, corn, tomatoes, nuts, many different seeds, eggs, a few specific vegetables (inc spinach), most fruits, all citrus and citric acid … It has been a very discouraging process. There are specific instances of my eating a food with no problem for several months, then suddenly developing a dramatic symptom of intolerance (or allergy), and having to take yet another food off the list. I have began to add a few foods back in (I eat a little dairy now, and some less common nuts, like pistachios – only in great moderation).

    My symptoms, when I eat a food that is “off the list” include painfully dry and puffy eyes, a dry, sore feeling in my throat, and muscular pain. Sometimes I begin sneezing, but this is more rare. Lately, I have begun to have reoccurring bouts of a rash and swelling on my upper lip (the most true “allergic” reaction I’ve had so far).

    In addition to these things, I struggle with fatigue and I present with Multiple Chemical Sensitivities. I am very sensitive to any type of syntheticc fragrance – perfume, cologne, and laundry products are the biggest culprits. I detect and suffer when exposed to synthetic fragrance in laundry when it is on other people’s bodies, even (sometimes) after multiple washings in fragrance-free laundry products. The chemical sensitivities are very difficult to mange, and extremely limiting. My symptoms are not dangerous (fortunately), but I experience (again) painfully dry eyes (sometimes burning), a dry, sore throat, stinging in my sinuses, and muscle pain when exposed to any type of chemical odor (of which fragrances are the most common).

    The consensus among the last three doctors I have worked with (the first of whom is trained in functional medicine, though not certified) is that the blastocystis is behind most of these symptoms – or, at the least, is at the top of my total load, meaning it needs be dealt with first before I can move on to other potential issues.

    I have had three stool tests with Genova over the last three years, and I have watched my friendly bacteria counts steadily decrease. I am also quite low in magnesium, which my latest doctor said is a nutrient that the parasite will consume regardless of how much I take in. I have researched leaky gut, and can understand the food intolerances (and continued sensitization to new foods) within this paradigm. It also makes sense to me that if my system is not digesting food well, and I am dealing with a lot of inflammation, that this going to exacerbate fatigue and environmental senstivities.

    So, overall, I can get behind the need to deal with the blastocystis in theory – but in practice it has been a discouraging process. Your in depth explanation of immune health in the gut, however, is quite encouraging and inspirational – as reading it gives me a picture of approaching the blaso situation differently. I have more hope of healing.

    My questions are two fold. Food intolerances are not listed as a primary symptom of blasto (only one person in this long thread of comments mentions food intolerance, and the most common list of blasto related symptoms – which is given multiple times in this thread – makes no mention of food intolerances). What is your view on the potential connection between food intolerance (and allergy) in my profile and the blastocystis that I continue to test positive to?

    Second, the main therapeutic processes described here – for supporting healthy immune function and repairing the mucosal lining – appear to focus on the large intestine (and not the small intestine). Given my difficulty with food intolerances (and ongoing sensitization), is working on repairing my large intestine enough? Do I need information on repairing gut health that is specific to the small intestine? If so, can you offer some suggestions?


  • Trevor Koch
    July 9, 2014 4:22 pm

    Dear Michael,
    My daughter and I were recently shown to have d fragilis and blasto I had Pylori as well. How common is this problem. My daughter basically stopped functioning chronic fatigue and terrible anxiety no school no public places. A web site[bad bugs] suggested an antihistermin it stopped my daughters symptoms straight away but had no effect on me.
    I believe I,ve had the problem since childhood. I fell into septic tank when 8 yr old. Always sick doctors could never find anything wrong. I had a weeping [chronic} appendix for 10 years I was very very skinny 55 kilo could there be a link of parasites with chronic appendix. I’m 45 now and constantly sick. Still have bugs . Symptoms improve with antibiotics but come back again when treatment is finished.
    Thank you for any help

  • Hello Michael
    I am afflicted with blastocystis for 6 weeks now after eating out. Both my husband and I got affected but he has been symptom free for 1.5 weeks now. I weighed 106 before it struck and down to 96 lbs now. The symptoms come and go. I would be okay for 2-3 days and then my system gets attacked with a vengeance. I had an yeast infection before it began which has still not gotten better. I have no appetite and no energy left. The doctor prescribed me flagyl which made my symptoms more worse. I stopped medication and worked on my diet eliminating all foods that convert to sugar. Symptoms are better but I am not sure if another attack is lurking in my future. Knowing you don’t give specific advice, I wanted to ask if the regimen below should be altered for my body weight. Here is what I plan to do.

    ADP (300 mg)
    SB & MOS (5 billion SB and MOS 200 mg)

    Should I add anything for the yeast infection? Is it common to see the two together?


  • Hi I have B hominous in high numbers I have tried the natural route of oil of oregano and black walnut etc I have not eradicated this, I really don’t know what to do, I have been told by my specialist to have a colonoscopy infusion I was wondering if there is a specialist who can help erradicate the bug without the use of having to have a colonoscopy infusion? Any help would be great thanks

  • Hello Michael

    I’ve just been diagnosed with Blastocystis by a Genova Diagnostics Comprehensive Digestive Stool Analysis. My main symptom is chronic constipation which has got worse in the past few years and seems to occur in cycles.
    I’d prefer to treat the infection with the natural methods you recommend rather than drugs as the stool analysis showed my gut health was otherwise very good and I don’t want to wipe out all my good bacteria with antibiotics. However, I’ve just seen on the Optibac website that large doses of Saccharomyces boulardii can cause constipation and am worried about taking this product now, as I am already in a lot of pain owing to this condition. Please can you advise? Also, do Citricidal (grapefruit seed extract) and oregano oil kill good gut flora as well as pathogens?

    Mary Elena

  • Hi Michael
    I have recently been tested for parasites and came back positive for Blastocystis. Prior to this I was taking a bowel cleanser (Dr Christopher’s Lower bowel tonic) and it was keeping me from sleeping until about 2-4am in the morning. I kept going on this for a month and then got Impetigo (Streptoccoccus) which I tried to rid myself via Echinacea, Wild Oregano caspules and a few other things Eg colloidal silver), but it persisted. I then took antibiotics for 15 days and on the 13th day got severe gastro, vomiting so much bile it wasnt funny. A week later i got gastro again with slightly less vomiting and diarrhoea. Its been about 3-4 weeks since, I have been taking acidophilus capsule daily, probably not eating the best/too much sugar/dairy at times. I have some mild burping on occasion but no other real symptoms I think. Knowing that I have blastocystis now via the tests but with little symptoms should I just try to control the inner environment more to make it less hospitable for them (ie more cooked veges, fibre, low lactose, higher acidity) or should I take the antibiotics. I am scared to death about going on another round of antibiotics….I fear that it will cause it to flare up and for me to be debilitated, lose my job etc…. Your advice would be much appreciated. Thankyou….oh my mum is a nurse so she is freaking thinking I should take antibiotics but you know…..cheers Corey

  • I was about to ask the same question as Jane – is it ok to substitute apples with carrots for the soluble fibre? Would we need anything for the pectin?

  • Hello and thank you so much for the excellent information. I’m not sure if you’re still responding to comments but if you are, I would be extremely grateful for any insight you can offer.

    I’m wondering:

    1 – If non-symptomatic cases of Blastocystis infection would still cause systemic inflammation?

    2 – Is there a recommended treatment that would be safe while pregnant or trying to conceive?

    3 – Are you aware of any research that draws a parallel between Blastocystis infection and infertility or miscarriage?

    Thank you.

  • Hi Mike,

    I know you’re a busy man, but would much appreciate whether you know if there is anywhere in Europe that can do serological tests/testing for Blasto?

    Kind Regards,


  • my 19 yo daughter has for the past few years suffered many symptoms of gi pain, severe weight loss, blood in stool, indigestion, undigested food in stools, foul smelling gas, hair loss..she just had a stool sample done and the results were postivie for DF trophozoites and bhominis. she is now very underweight. can you recommend any good practitioners in vancouver, canada who can help us through the next steps? thanks so much!

  • Michael,
    You’re wisdom on this topic has been so helpful and encouraging. Keep up the work, friend! I understand that you cannot enter into personal consultations but as a recently confirmed blasto fellow, with an unsuccessful round of Flagyl and sulfamethoxazole, though I do have improved symptoms after a good diet, and have yet to receive the recent stool test results. I’m about to begin the natural way to hopefully rid completely.

    -Saccharomyces Boulardii
    -Standardized oil of oregano(ADP) 6 per day @ 3 pills twice a day) for 6- 8 weeks. 100 mg per meal = 300 mg daily.
    Vitamin A – 12,000iu per day
    1-3gms L glutamine powder
    3 grated (like cheese grater) apples per day

    I’m unsure of a few things:

    Saccharomyces: how much, how long?
    Does one need to supplement with iron since it’s harder to intake iron while taking oil of Oregano?
    Does the order of consumption matter?
    With or without food?

    Thanks in advance Michael! 🙂

    • Hey Mason,

      Curious if your method was successful? I know it is a few years later but I have been struggling for quite some time and hoping to get healthy asap!


  • Thank you so much for posting all this information. I just received a diagnosis of blastocystis after a few years of losing a lot of weight, nausea, burping, diarrhea, itchy skin, intermittent fecal incontinence (at night while asleep) and general malaise along with a longstanding diagnosis of fibromyalgia and stable bipolar disorder. So Doctoring is always a challenge because I tend to be considered a whining psychiatric case. :-(. Your posted information gives me a lot of information to consider further than the prescription regime of 750 mg of metronidazole 3 X a day for 10 days. I have been using medical marijuana edibles for sleep at night and that has actually controlled the peripheral neuropathy which was my worst fibro symptom. As long as I take my cococubes (decarboxylated marijuana in melted coconut oil that I put into ice cube trays for convenience and dosage) nightly the neuropathy stays minimal… if I stop it returns. However, now I am seeking to control the GI symptoms that have become intolerable. Thanks again for the wealth of information.

  • Blastocystis hominis and I have an extremely productive relationship. Although Blastocystis hominis is considered parisitic in nature we seem to get along just fine and have eventually become great friends!

  • Hello,

    Has anyone found a cure for blasto? My primary symptoms are chronic diarrhea and brain fog. The less common symptoms are joint pain, itchy skin, and very occasionally itchy anus. I have had these symptoms for 2 years at least, maybe longer, but hard to say when it started. Any information would be greatly appreciated.


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