Parasites
Parasite infections can drive persistent diarrhoea, malabsorption, nutrient deficiencies, and debilitating fatigue, making accurate testing and targeted care essential.
Overview
Bowel parasites - especially Blastocystis hominis, Dientamoeba fragilis, and Giardia - are common in Australia; while some are harmless colonisers, in many people they drive persistent diarrhoea, bloating, abdominal pain, and nutrient malabsorption, often after exposure to contaminated water or food (see the NHMRC fact sheet), and giardiasis prevalence is estimated at 2–7% in Australia (peer-reviewed estimate).
Because these symptoms overlap with IBS, parasitic infections can be mistaken for “functional” bowel issues; in fact, large outbreak studies show Giardia infection confers a sustained increase in IBS risk years later, while evidence on Blastocystis and D. fragilis suggests possible associations in some patients. Primary-care guidance recommends considering parasites and ordering targeted stool testing (e.g., for Giardia and ova/parasites) in persistent diarrhoea before settling on an IBS label.
Common Misunderstandings
A frequent misconception is that if you have a parasite, symptoms will be dramatic and immediate. In reality, many people have low-grade or fluctuating symptoms for months or years. Standard tests may miss some parasites, especially if they are shed intermittently. Patients often feel frustrated when told “it’s harmless” despite ongoing symptoms.
Moreover, the symptom of fatigue is underestimated - parasites can cause severe fatigue, and there is often nutrient malabsorption (e.g., iron, B12) plus low-grade inflammation that sustain exhaustion unless the parasite is eradicated.
How are Parasites Linked to Your Microbiome?
The interaction between parasites and the gut microbiome is complex:
- Some parasites may disrupt the balance of gut bacteria, reducing beneficial species and promoting inflammation (gut.bmj.com).
- Others may interact with the immune system in ways that change how the microbiome functions, potentially worsening symptoms in those with IBS-like conditions (nature.com).
- Research into Blastocystis & D. fragilis suggests that symptoms may be more likely when there is co-existing bacterial dysbiosis or other gut disorders.
- Giardia infection is known to cause long-lasting microbiome changes even after the parasite is cleared, contributing to post-infectious IBS in some people (thelancet.com).
Symptoms
Loose or frequent stools
Abdominal bloating, cramps or discomfort
Excess wind
Fatigue and low energy
Symptoms that flare after certain foods or during stress
The Microbiome Clinic™
Our treatment approach for Parasites includes:
Gut Microbiome Test
Profile the gut to identify dysbiosis that may be affecting symptoms or treatment using the Gut Microbiome Test.
Targeted Antimicrobial Strategies
Antibiotics and plant-based or pharmaceutical antimicrobials (where appropriate) to kill parasites in the gut.
Probiotics and Prebiotics
Targeted probiotics and prebiotics are introduced slowly to restore balance and biodiversity of microbes in the gut without fuelling overgrowth.
Individualised Nutrition Plans
Nutrition strategies to support recovery and enhance your overall health such as a tailored low-FODMAP diet or fibre consumptions strategies.
Suspect you might have Parasites?
