To Treat Or Not To Treat Blastocystis Hominis


What Is Blastocystis Hominis?

Blastocystis hominis is a parasite that inhabits the gastrointestinal tract of humans and many animals. It has a worldwide distribution, and, is often identified as the most common parasite reported in human fecal samples (5–15% of individuals in developed countries and 50–100% of individuals in developing countries).

The parasite has been known since the early 1900s but only in the last decade has the biology and pathogenicity of this parasite undergone more intensive studies and its pathogenic potential is still controversial. For many years, it has been suggested that Blastocystis is a commensal organism living in the human intestine. 

This is partly because while there are many case reports, and epidemiological and microbiological studies support a pathogenic role of Blastocystis in causing intestinal inflammation and urticarial symptoms, there are many reports on asymptomatic colonisation by Blastocystis.

It is made more challenging because:

a total of 17 subtypes of Blastocystis Hominis have been identified so far – and perhaps not all of them are pathogenic.

How Do We Get Infected?

The difference in colonisation rates around the world can be partly explained by poor hygiene practices and consumption of contaminated water or food in developing countries. The fecal–oral route is considered to be the main mode of transmission.

Signs & Symptoms Of Blastocystis

The most common symptoms associated with Blastocystis infection include diarrhoea, abdominal pain and vomiting.

Recent epidemiological data demonstrate the association of Blastocystis with a variety of disorders, such as diarrhea, abdominal pain, fatigue, constipation, flatulence, chronic gastrointestinal illnesses (irritable bowel syndrome), and skin rash or urticaria. 

results support the hypothesis that Blastocystis might be linked to the pathophysiology of IBS-C and intestinal flora imbalance

For those with stool results at hand, it was shown that proteases secreted from Blastocystis isolates can degrade human secretory immunoglobulin A (SIgA), so, low levels of SIgA in a stool test alongside Blastocystis Hominis may get you thinking about certain nutritional interventions (see below).

There have been several case reports suggesting that Blastocystis is related to urticaria. The amoeboid forms of Blastocystis ST3 were found in a case of acute urticaria and the authors suggested that cutaneous symptoms may be caused by disruptions to the immune homeostasis as the host produces an inflammatory response.

One study showed a possible link between Blastocystis and IBS where there was an infection rate of 46% in IBS patients and only 7% in the control group was shown

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To Treat Or Not To Treat Blastocystis?

Blastocystis was positively associated with high intestinal bacterial genus richness

When Blastocystis is detected by microscopy or PCR in diagnostic examinations of faecal samples from humans with suspected disease, it is often not possible to determine if the finding represents acute infection or intestinal colonization.

These are two important points to acknowledge – we shouldn’t treat Blastocystis just because we find it on testing, and there may actually be benefit from being colonised with Blastocystis – namely a higher bacterial genus richness – something we are all striving for!

One study concluded that:

“The associations between Blastocystis and the bacterial microbiota found in this study could imply a link between Blastocystis and a healthy microbiota as well as with diets high in vegetables.”

Treatment failure is common and eradication of Blastocystis can be difficult to achieve. It is unknown whether this is due to poor drug efficacy, a failure of the host defence in eliminating a pathogen despite an appropriate drug effect, or if persistent Blastocystis findings in symptomatic disease signify that this organism constitutes a normal and stable part of the gut microbiota.

Treating Blastocystis Hominis

Furthermore, some strains develop resistance against currently recommended drugs, such as metronidazole; therefore, the use of natural remedies or special diets has many positive aspects that may address this problem.

The literature has revealed that garlic, ginger, some medical plants, and many spices contain the most effective organic compounds for parasite eradication. They work by inhibiting parasitic enzymes and nucleic acids, as well as by inhibiting protein synthesis.

Probiotics such as saccharomyces boulardii may also be beneficial when treatment is required.

Natural herbs, vegetables, or spices as an alternative for blastocystosis treatment not only reduce drug resistance, but also their side effects and the cost of treatment, especially in developing countries. 

it is known that the composition of the intestinal bacterial populations modulates the progression of protozoan infection and the outcome of parasitic disease.

Again this final quote takes us back to point that perhaps we should look to optimise gut health via supporting a healthy mucosal immune system via a colourful, fibre rich diet. By supplementing probiotics such as saccharomyces boulardii rather than instantly thinking we need to ‘kill, kill, kill’ and take high dose antimicrobials.


Since a gut microbiota with high diversity is generally considered healthy, Blastocystis might be seen as an indicator of gastrointestinal health, an opinion also voiced by other researchers

We shouldn’t simply treat blastocystis hominis because it is detected in a stool test. It needs to be put in the context of the other markers/results within the test results, as well as the clients symptoms. There is also more than one way to manage a parasitic infection like Blastocystis hominis and this includes supporting the health of our immune system, which might include supplementing with probiotics such as Saccharomyces Boulardii, but certainly includes appropriate amounts of exercise, managing our stress, optimising our sleep habits and evening routine, and eating a diverse, nutritional and fibre rich diet.


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