Parasite PCR profile – stool test for DNA of gut protozoa

Blastocystis is the single-celled organism most frequently found in the human gut. A review summarises that most studies show it to be a common component of a healthy gut microbiome, while some studies describe a decrease in beneficial bacteria (PubMed 33630979).

Whether Blastocystis causes complaints is disputed. A meta-analysis of 17 studies found it more often in people with irritable bowel syndrome than in healthy people (PubMed 28668983). A population-based Danish study, by contrast, found it slightly more often in people without irritable bowel syndrome (PubMed 25229421). A recent review points out that sensitive PCR methods find Blastocystis in 15–25% of people tested and that a positive result often triggers treatment even though its clinical significance is uncertain (PubMed 42838172).

What this means for you: a positive result is not proof that Blastocystis causes complaints. Whether it plays a role for you is a medical judgement in the context of all findings.

Dientamoeba fragilis is a protozoan of the large intestine found worldwide in connection with gastrointestinal complaints. A review describes that little is known about its life cycle and transmission and that whether it causes disease is disputed (PubMed 27170141).

In the Danish population study, Dientamoeba was found in 35% of people without irritable bowel syndrome and in 23% of people with it (PubMed 25229421); the meta-analysis found no association with irritable bowel syndrome (PubMed 28668983). It is frequently found in children.

What this means for you: a positive result alone does not explain complaints. Interpretation is medical.

Entamoeba histolytica is an amoeba found mainly in tropical regions. It can attack the gut lining (amoebic dysentery) and in rare cases reach the liver via the bloodstream. Under the microscope it looks exactly like the harmless Entamoeba dispar – only genetic methods distinguish the two (PubMed 12660071, review in the Lancet).

PCR can distinguish E. histolytica from E. dispar directly in stool and was more sensitive than microscopy and culture in one study (PubMed 12454128).

Positive means: genetic material of E. histolytica was found. This result belongs in a doctor's hands promptly, even without complaints. The amoeba is not on the national list under Sec. 7 IfSG; whether notification is required is clarified by the laboratory and the doctor.

Cyclospora cayetanensis is a protozoan acquired via contaminated food – often fresh fruit, salad or herbs – or water. It can cause gastrointestinal illness with diarrhoea, which can take a more complicated course with weakened immunity. According to a review, its importance for health is probably underestimated (well established, PubMed 30885589).

Positive means: genetic material of Cyclospora was found. Assessment and any treatment are carried out by a doctor.

Giardia lamblia and Cryptosporidium are notifiable pathogens under § 7 IfSG of the German Infection Protection Act. A positive result is reported by the laboratory to the public health office; diagnosing and treating such an infection is reserved for doctors under § 24 IfSG.

What this means in practice: a positive result is assessed in a doctor's practice, not in a results consultation with a naturopath. For children under six in community facilities (§ 34 IfSG) and for people working with food (§ 42 IfSG), additional rules apply in Germany in the case of infectious diarrhoea; what applies in an individual case is clarified by the doctor or the public health office.

For context: according to a review, Giardia infections are just as often without complaints as with them (PubMed 27501461). Cryptosporidium is of particular importance in people with weakened immunity (PubMed 25278220). What a result means for you can only be judged by the doctor.

PCR specifically amplifies short sections of genetic material and assigns them to a species. The result is qualitative: positive (found) or negative (not found). There is no quantity.

Negative means: no genetic material of the six measured protozoa was found in this one sample. Other pathogens – bacteria, viruses, worms – are not examined. A negative result therefore does not explain where complaints come from.

Positive means: genetic material was found. This does not show whether the protozoan causes complaints – with Blastocystis and Dientamoeba this is often precisely what is unclear. Interpretation is medical.

"Intestinal parasites" is an umbrella term for organisms that live in the gut and feed off their host there. There are two large groups:

• Single-celled organisms (protozoa): microscopically small organisms consisting of a single cell, such as Blastocystis, Dientamoeba, amoebae, Giardia, Cryptosporidium or Cyclospora. They are usually taken up via contaminated water, food or hands.
• Worms (helminths): multicellular animals such as pinworm, roundworm or tapeworm. This test does not measure them – the worm profile does.

Not every protozoan in the gut is a pathogen. Some – such as Blastocystis – are frequently found in healthy people and are regarded by part of the research community as residents of the gut microbiome (PubMed 33630979).

Traditionally, stool is examined under the microscope for cysts and eggs; this often requires samples from several days. PCR, by contrast, looks for the genetic material of the protozoa. A clinical review on persistent diarrhoea names both routes – microscopy and PCR including multiplex PCR – as available methods (PubMed 27357241).

PCR can distinguish pathogens that look the same under the microscope, such as E. histolytica and E. dispar (PubMed 12454128). Its high sensitivity has a downside, however: it finds protozoa such as Blastocystis and Dientamoeba much more often, without clarifying whether they cause complaints (PubMed 42838172).

Parasite test in blood? For the protozoa in this profile, stool is the usual sample material. Whether blood tests are useful in addition is decided by the doctor.

This question is not settled in research. In favour of a harmless resident, or even one belonging to a healthy gut, is that Blastocystis is frequently found in healthy people and in many studies goes along with a diverse microbiome (PubMed 33630979). In the Danish population study, too, it was not less common in people without irritable bowel syndrome (PubMed 25229421).

In favour of a possible role in complaints is the meta-analysis that found Blastocystis more often in irritable bowel syndrome (PubMed 28668983). A 2026 review summarises trials, cohorts and experience from faecal microbiota transplantation and proposes a cautious approach to positive results (PubMed 42838172).

To be honest: a "Blastocystis positive" result is common and of little significance on its own. Interpretation belongs in a medical consultation.

Many people with intestinal protozoa have no complaints. Where complaints do occur, research describes the following depending on the pathogen:

• Diarrhoea, including watery or persistent: described with several protozoa, especially after travel; persistent diarrhoea affects about 3% of travellers to countries with basic infrastructure (PubMed 27357241, well established).
• Bloating, abdominal pain, changing stool: described with Blastocystis and Dientamoeba, but a causal link is disputed (PubMed 27170141, PubMed 28668983, under discussion).
• Bloody diarrhoea: with amoebic dysentery caused by E. histolytica (PubMed 12660071, well established) – a warning sign for immediate medical assessment.
• Irritable-bowel-like complaints after a gut infection: described after Giardia infections (PubMed 27501461, observed in studies).
• Diarrhoea after fresh fruit, salad or herbs: typical transmission route of Cyclospora (PubMed 30885589, well established).

Important: these associations come from studies of groups of people. They do not show what causes complaints in an individual. The test does not explain complaints and does not make a diagnosis. Please have persistent or new complaints assessed by a doctor first.

With these signs, a medical examination is the first step, not a home test – and waiting is not a good idea:

• Blood or mucus in the stool, black stool
• Fever, especially together with diarrhoea
• Diarrhoea after travel to tropical or subtropical countries, especially if it lasts more than a few days
• Severe or increasing abdominal pain, persistent vomiting
• Signs of dehydration (little urine, dizziness, dry mouth), especially in young children, older people and during pregnancy
• Unintended weight loss or fatty stools
• Weakened immunity, for example due to cortisone, chemotherapy, other immunosuppressive drugs or HIV infection
• Diarrhoea in people who work with food or in nurseries, schools or care, and in children attending a nursery

In Germany, stool examinations ordered by a doctor because of complaints are usually covered by statutory health insurance.

A positive result is an indication that is assessed by a doctor. Take the report to your GP or paediatrician, and if you have returned from travel, to a tropical medicine clinic. There it is decided whether further examinations are needed and whether and how to treat.

Giardia or Cryptosporidium positive: the laboratory reports the result to the public health office; diagnosis and treatment are reserved for doctors. The public health office may contact you.

Blastocystis or Dientamoeba positive: here the significance is particularly disputed (PubMed 42838172). Whether anything needs to be done at all belongs in the medical consultation.

The free results consultation with the ORY expert team or with your doctor or naturopath, for example from the ORY expert network helps you understand the report and prepare for the medical appointment. It does not replace medical assessment.

This page does not recommend any products – neither medicines nor home remedies, oils or herbal "parasite cleanses". Whether a positive result should be treated at all, and with what, depends on the pathogen, the complaints and your health situation. This is decided by the doctor.

With Blastocystis and Dientamoeba in particular, research points out that positive results often trigger treatment even though it is unclear whether it is needed (PubMed 42838172). For notifiable pathogens, treatment is reserved for doctors by law.

Collecting the sample takes a few minutes. Important points:

• No contact with toilet water: collect the stool with the stool collection aid.
• Only open the yellow cap: insert the sampling stick into the stool in four places, close the tube and swirl it. Do not open the white cap.
• Complete and sign the request form, label the tube and place it in the transport tube.
• Send Monday to Thursday, not on Fridays. Cooling is not needed.

Please mention medication and any recent treatment for parasites in the results consultation.

The kit is dispatched the next working day. The report is usually available 7–21 days after the sample arrives at the laboratory, not from the date of order. As soon as it is ready, we will inform you and you can book the free results consultation.

If you have acute complaints, do not wait for the result – see a doctor.

The parasite PCR profile costs €150.50 including VAT, shipping, return shipping and results consultation.

Statutory health insurance in Germany usually does not cover this self-test. If a doctor orders a stool examination because of complaints, insurance usually covers it. Private health insurance reimburses laboratory analyses fully, partly or not at all, depending on the contract – the section below describes the process.

Different examinations suit different questions:

• Parasite PCR profile (this page, €150.50): stool PCR for DNA of six intestinal protozoa.
• Worm profile (€125.00): stool PCR for DNA of several worm species and microsporidia.
• Basic gut profile (€285.00): broader stool profile on microbiome, leaky gut markers and histamine.
• Gut-brain axis complete (€116.00): stool test for neurotransmitters, without parasites.

With diarrhoea after travel, fever or blood in the stool, a medical examination is the first step. Which analysis makes sense beyond that is something to discuss in the free initial consultation with the ORY expert team or with your doctor or naturopath, for example from the ORY expert network.