Blastocystis Hominis Treatments – Clinical Trial Results

Blastocystis is a common micro-organism which lives in the intestines[1] and is among the most common human parasites in the world and is spread globally.[2][3] It is present in the stools of people that have eaten tainted food or water.[4][5] It can be detected in healthy individuals that have no gastrointestinal issues, and it is also present often in the stools of people with diarrhea, stomach pain or other gastrointestinal disorders.[5][6]

A thorough understanding of Blastocystis’ nature and its relationship with other species is not clear, but is an active research topic. Blastocystis infection is described as blastocystis.[1] Many types of the organism will be much more likely to identify with signs of an infection. Most generally, blastocystis merely continues to live without causing any harm in a person’s gastrointestinal tract. Normally, the infection clears by itself. There is yet to be a proper,  concrete treatment for these infections.[5][6]

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Table of Contents

Blastocystis treatment and clinical trials



Blastocystis Hominis is a protozoan intestinal parasite related to Stramenopiles’ Blastocystis family-a wide variety of species including brown algae, water molds, and diatoms. Researchers have repeatedly tried to arrive at precise assumptions on many aspects of B. hominis.[7] It has a broad regional range and is distributed around the globe in places of all income levels. Many protozoans in your gastrointestinal system usually live quietly and are harmless or even helpful, while a few cause disease.[5][6]


It’s classification as a true disease is uncertain-although it ‘s not known to be the cause of patients with digestive problems, and many carriers are asymptomatic. Blastocystis hominis study is sparse, with huge gaps remaining in our knowledge of its development cycle, transmission pathways, period of incubation, epidemiology, and possible treatments.[8]




Many published studies have indicated that symptoms would occur around 50% to 80% of individuals who have Blastocystis.[9][10] Probably linked common symptoms of Blastocystis hominis may include watery or loose stools, diarrhea, abdominal pain, anal itching, weight loss, constipation, and excess flatulence. These were all recorded in people with Blastocystis infection.[1][5] Again, many individuals have no symptoms whatsoever, and the organism can be present in people who are both healthy and sick. When you have signs and symptoms, such as diarrhea or cramps, that last for more than three days, see your doctor.




Blastocystis hominis’ exact transmission mechanisms remain unclear. Fecal-oral transmission is by far the most established mechanism and latest research have shown that dissemination requires only the parasite’s cyst form.[11] Scientists believe that when people eat infected food or are exposed to an infected person’s feces, such as changing a diaper in a child care environment, blastocystis gets into the digestive system.[5][12]


For less developed areas, infection rates were found to as high as 100%.[2][3] High infection rates are observed in individuals who work with animals in developing countries.[3][13] It is not yet clear to what extent human-human, human-animal, and animal-human transmission occurs. While some studies offer support for all three paths, laboratory experiments have yet to provide definitive proof of either.[12][14]




By taking precautions, especially when traveling in high-risk countries, you may be able to avoid Blastocystis hominis or other gastrointestinal infection.[1][5] When you exercise proper personal hygiene there is no chance of transmitting infection. It involves extensive hand washing, after using the toilet and before touching food, with soap and warm water. Because of the parasite ‘s unknown infective existence and transmission mechanisms, there are no common public health or preventive approaches explicitly aimed at Blastocystis Hominis. Nevertheless, the Center for Disease Control and Prevention (CDC) mentions the following specifically as highly beneficial preventive and control measures:[1][14]


  • Wash your hands with soap and warm water constantly and regularly, especially after handling or being near fecal matter.

  • Avoid consuming food or water that may be dirty.

  • Check, wash, and peel all raw produce before consumption.

  • Avoid drinking unboiled and unfiltered water and avoid uncooked foods washed with unboiled water when in countries where the water may be impure or contaminated. 




It could be difficult to diagnose the cause of your diarrhea. Even if your stool contains Blastocystis hominis it might not cause your symptoms.[15] Many forms of blastocystis can correlate more with symptoms. Discovering Blastocystis should be followed up by a thorough examination for other potential causes of the symptoms in stool samples.[1] Most generally, it means that you’ve been exposed to infected food or water containing certain species that may cause digestive problems.[15]


Your doctor would likely take your medical information, question you about recent events, such as travel, and do a physical examination. A collection of laboratory tests help identify parasites and other non-infectious causes of digestive problems[15]:


  • Stool (fecal) exam. This examination checks for parasites or for their eggs. Your physician can give you a special bottle for your stool samples that contains preservative fluid. Refrigerate the samples — don’t freeze — until you take them to the doctor’s office or laboratory.

  • Endoscopy.If you have symptoms but the fecal examination doesn’t show the source, your doctor can ask for this test. A doctor, usually a gastroenterologist, sticks a tube into your mouth or rectum after you’re put to sleep to check for the source of the symptoms. It will be necessary to fast the night prior. 

  • Blood tests. A test which can detect blastocystis, but is not commonly used. The doctor may however prescribe blood tests to check for other causes of the symptoms and signs.


Blastocystis hominis is identified on a stool sample using microscopy. The CDC suggests combining samples, and taking at least three different samples before verifying a negative result.[14][16]


Blastocystis could last weeks, months, or years in the intestinal tract.[1] When you have Blastocystis hominis associated diarrhea, it’s likely to be self-limiting. However, you lose vital fluids, salts, and minerals whenever you have diarrhea which can cause dehydration. In particular, children are vulnerable to dehydration.[5][6]




When you have no signs or symptoms of Blastocystis hominis, then you don’t need medication. In a few days, mild signs and symptoms may improve on their own.[15]


Drugs for treating blastocystis are available by prescription. Often, however, medicine is not successful, so it may be important to look for other potential causes of your symptoms.[1][17] Potential medications for treatment include antibiotics such as metronidazole or tinidazole, or combination medication like sulfamethoxazole and trimethoprim. There are also specific antiprotozoal medications, such as paromomycin or nitazoxanide[15]:


While Blastocystis Hominis pathogenicity remains uncertain, anti-protozoan drugs were used to treat individuals in whom the parasite is present. The current treatment option of choice is the drug Metronidazole which still, shows signs of resistance by blastocystis, or limited effects in some.[14][18]


The response to the Blastocystis hominis medication varies greatly from person to person. And since the organism may not be the source of the illness, improvement may be due to the impact of the drug on another organism.[15][17] 

Unless your symptoms are linked to Blastocystis hominis, they’ll probably go away by themselves before you see the doctor. Drink plenty of fluids. Oral rehydration products — accessible worldwide through pharmacies and health departments — can restore missing fluids and electrolytes.[15]

We have spent countless months researching cures and treatments across many clinical trials and studies. The number one treatment we have seen work is Paromomycin Sulphate. The top natural solution is high doses of Saccharomyces boulardii. Many trials and doctors still use and recommend Metronidazole even though the resistance seems to be getting higher. Metronidazole had up to 88% of clinical remission and a six month fecal clearance of up to 80%. With 

With metronidazole, a high proportion of patients achieve clinical remission (88%) and a 6 month fecal clearance (80%).[19]

Treatment using Saccharomyces boulardii is always recommended as it assists the stomach in killing the parasite rather than the treatment killing it. Both options are also possible but seek advice from your medical practitioner as every case seems to be different. 


Generally patients who have trouble beating the parasites may need up to a three week course to kill the parasite, let the eggs hatch and then kill the newborn parasites if they are at advanced stages in your body. Treatments of up to 750mg 3 times a day for 3 weeks have been prescribed in severe cases which have proven to work at a higher percentage although still many debated opinions. 


“Although many Blastocystis infections remain asymptomatic, recent data suggest it also causes frequent symptoms. Therapy should be limited to patients with persistent symptoms and a complete workup for alternative aetiologies”.



  1. Centers for Disease Control and Prevention . (n.d.). CDC – Parasites. Retrieved July 1, 2020, from

  2. El Safadi, D., Gaayeb, L., Meloni, D., Cian, A., Poirier, P., Wawrzyniak, I., Delbac, F., Dabboussi, F., Delhaes, L., Seck, M., Hamze, M., Riveau, G., & Viscogliosi, E. (2014). Children of Senegal River Basin show the highest prevalence of Blastocystis Sp. ever observed worldwide. BMC Infectious Diseases, 14(1).

  3. Roberts, T., Stark, D., Harkness, J., & Ellis, J. (2014). Update on the pathogenic potential and treatment options for Blastocystis sp. Gut Pathogens, 6(1), 17.

  4. Roberts, T., Stark, D., Harkness, J., & Ellis, J. (2014). Update on the pathogenic potential and treatment options for Blastocystis sp. Gut Pathogens, 6(1), 17.

  5. Blastocystis hominis – Symptoms and causes. (2019, January 29). Mayo Clinic.

  6. Coyle, C. M., Varughese, J., Weiss, L. M., & Tanowitz, H. B. (2011). Blastocystis: To Treat or Not to Treat… Clinical Infectious Diseases, 54(1), 105–110.

  7. Dunn, L. A., Boreham, P. F. L., & Stenzel, D. J. (1989). Ultrastructural variation of Blastocystis hominis stocks in culture. International Journal for Parasitology, 19(1), 43–56.

  8. Boorom, K. F., Smith, H., Nimri, L., Viscogliosi, E., Spanakos, G., Parkar, U., Li, L.-H., Zhou, X.-N., Ok, Ü. Z., Leelayoova, S., & Jones, M. S. (2008). Oh my aching gut: irritable bowel syndrome, Blastocystis, and asymptomatic infection. Parasites & Vectors, 1(1), 40.

  9. Iseki, M., Ali, I. K. M. D., Hossain, M. B., Zaman, V., Haque, R., Takahashi, Y., Yoshikawa, H., Wu, Z., & Kimata, I. (2004). Polymerase chain reaction-based genotype classification among human Blastocystis hominis populations isolated from different countries. Parasitology Research, 92(1), 22–29.

  10. Amin, O. M. (2002). Seasonal prevalence of intestinal parasites in the United States during 2000. The American Journal of Tropical Medicine and Hygiene, 66(6), 799–803.

  11.  Yoshikawa, H., Yoshida, K., Nakajima, A., Yamanari, K., Iwatani, S., & Kimata, I. (2004). Fecal-oral transmission of the cyst form of Blastocystis hominis in rats. Parasitology Research, 94(6), 391–396.

  12. Yoshikawa, H., Abe, N., Iwasawa, M., Kitano, S., Nagano, I., Wu, Z., & Takahashi, Y. (2000). Genomic Analysis of Blastocystis hominisStrains Isolated from Two Long-Term Health Care Facilities. Journal of Clinical Microbiology, 38(4), 1324–1330.

  13. Parkar, U., Traub, R. J., Vitali, S., Elliot, A., Levecke, B., Robertson, I., Geurden, T., Steele, J., Drake, B., & Thompson, R. C. A. (2010). Molecular characterization of Blastocystis isolates from zoo animals and their animal-keepers. Veterinary Parasitology, 169(1–2), 8–17.

  14. (n.d.). Blastocystis Hominis. Retrieved July 1, 2020, from

  15. Blastocystis hominis – Diagnosis and treatment – Mayo Clinic. (2019, January 29). Mayo Clinic.

  16. Centers for Disease Control and Prevention . (n.d.). CDC – Blastocystis – Resources for Health Professionals. CDC – Blastocystis. Retrieved July 1, 2020.

  17. Centers for Disease Control and Prevention. (n.d.). CDC – Blastocystis – Biology. CDC – Blastocystis. Retrieved July 1, 2020

  18. Rossignol, JF et al. (2005). Clin Gastroenterol Hepatol. 2005 Oct;3(10):987-91.

  19. Aguilar C, Lucia JF. An overview of Blastocystis hominis infection and published experience in hemophilic population. J Coagul Disord. 2010;2:1–4. [Google Scholar]


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