Treating Blastocystis Hominis

A reader asked me for a summary of the latest treatments for this parasite. It may be a trigger for IBS and thus CFS.

“Blastocystis exhibits low host specificity, and many different species of Blastocystis can infect humans and by current convention, any of these species would be identified as Blastocystis hominis. Blastocystis is one of the most common human parasites in the world and has a global distribution….95% of papers published in the 10 years prior identified it as causing illness in immunocompetent individuals… Researchers have reported that patients with Irritable bowel syndrome may provide a reliable source for xenic Blastocystis isolates” [Wikipedia] Note: some people can have it with no apparent symptoms.

PubMed Literature

There are 890+ studies on PubMed.

  • “For refugees to North America… 36.4% from Asia have positive results” [2017]
  • ” 1 in 200 ready-to-eat packaged salads in Italy were found to have it”[2017] – no published test results for the USA…
  • Examination of potential healthy donors for FMT, 15 / 116 (13%) had one or more parasites. [2015]
  • Modulating the Gut Micro-Environment in the Treatment of Intestinal Parasites.[2016]
    • ” Reported prevalence ranges from 2%–50% with the highest rates reported for developing countries with poor environmental hygiene. Infection appears to be more common in adults than in children [12,13].”
  • “It has been well described a positive association between IBS and Blastocystis hominis infections, one of prevalent parasites in Chile. In other countries, is also described a relationship between IBS and amebiasis and giardiasis. ” [2016]
  • Eradication of Blastocystis hominis prevents the development of symptomatic Hashimoto’s thyroiditis: a case report.[2015]
  • Hypoalbuminemia as a predictor of diarrhea caused by blastocystis hominis.[2013]
  • Low efficacy of metronidazole in the eradication of Blastocystis hominis in symptomatic patients: Case series and systematic literature review. [2017]
  • “Eradication of Blastocystis is essential in some cases where it is the only infectious agent and patient is suffering from some symptoms. In such cases, metronidazole is the drug of choice but its efficacy is relatively low in some cases. Other agents used include trimethoprim-sulfamethoxazole, paromomycin, and furazolidone.” [2016]6 had
  • Examination of potential healthy donors for FMT, 15 / 116 (13%) had one or more parasites. [2015]
  • In vitro effect of some Egyptian herbal extracts against Blastocystis hominis. [2015]
    • “Cultured fecal samples of B. hominis have identified several forms of the organism; vacuolar, granular, amoeboid and cyst forms within 24 hr. Nitazoxanide treatment significantly (P < 0.001) lowered the parasite number after 48 hr. (mean, 337.5 ± 17.67) /ml. The reduction rate after 48 hr. compared to PBS was 93.33%. Ginger treatment significantly (P < 0.002) lowered the number of the parasite after 48 hr. (mean, 335 ± 7.07)/ml. Moreover, garlic treatment also significantly (P < 0.002) lowered the number of the parasite after 48 hr. (mean, 382.5 ± 10.60)/ml.”
  • Blastocystis: Consensus of treatment and controversies.[2013]
    • “Recently, the finding of different subsets of Blastocystis exhibiting resistance to metronidazole and associated with variable degrees of symptoms has underscored the importance of typing the subsets of the parasite in order to foretell the clinical response and the need to treat. ”
    • ” A 2006 text described an USA patient returning from Nepal with chronic Blastocystosis who was treated without success over a period of 3 years with iodoquinol, paramomycin, doxycycline, albendazole, tinidazole, ornidazole, quinacrine, nitazoxanide, rifaximin, furazolidone, cotrimoxazole, itraconazole, ketoconazole, and various combinations of these drugs.[17]”
    • ” In at least 10% of IBS patients, Blastocystis cannot be successfully treated with metronidazole.”
    • “TMP-SMX has been shown to have good effects on the cure rate and the clinical symptoms in patients with Blastocystis infection…Whether the drug has a direct effect on the parasite itself or kills the essential intestinal bacteria for the survival of Blastocystis is not clear”
    • In a randomized single blinded clinical trial in symptomatic children who had Blastocystis positive stools, both clinical and parasitological cure rates were 94.4% with S. boulardii in comparison with 73.3% achieved in the metronidazole treated group. These findings challenge the existing guidelines for treatment.[8]
    • A few traditional Chinese medicinal herbs have also been examined for in vitro activity against Blastocystis (Brucea javanica and Coptis chinensis). Their inhibitory activity was not as great as with similar concentrations of metronidazole.
    • Blastocystis isolates from IBS patients mostly genotype-1 have demonstrated increased susceptibility to garlic at 0.01 mg/ml. Other investigational agents such as ginger, black pepper, and white cumin did not have significant inhibitory effect in drug susceptibility assays

Bottom Line

For non-prescription treatment, Garlic (high dosages) and Saccharomyces boulardii (250mg take 2x/day) appears to be most favorable.

  • Warning: S. Boulardii is 250 mg of it alone (around 3 BCFU is my best estimate), not a 250 mg capsule containing some of it and other stuff bringing the capsule up to 250mg. For example:

For prescription treatment, metronidazole concurrent with trimethoprim-sulfamethoxazole (TPM-SMX) appears most favorable.

This is an education post to facilitate discussing this with your medical professionals. It is not medical advice for the treatment of any condition. Always consult with your medical professional before doing any  changes of diet, supplements or activity. Some items cites may interfere with prescription medicines.