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‘Diagnostic procedures
employed currently in
laboratories around the
UK are not optimal for
the detection of D. fragilis
and B. hominis’ Relatively few laboratories in England and Wales use suitable staining methodologies; consequently, many are likely to encounter B. hominis initially in unstained preparations. In fact, many of the cases of B. hominis seen in our laboratory are found by direct microscopy and confirmed subsequently with a trichrome stain. In view of this, it may be pertinent to address proficiency to detect B. hominis by the ability to report it both in unstained and stained preparations. It is our impression that the variations in the reporting of D.fragilis reflect more the attention that is paid to the parasite and the technique that is used than to the actual incidence. Even under ideal circumstances, a single stool specimen is diagnostic only 50% to 60% of the time; three samples increases the sensitivity to 80% and six samples to 95% . D. fragilis is believed to be rare; however, when stool specimens are collected and preserved in polyvinyl alcohol or other fixative, followed by permanently-stained smears, the recovery rate increases markedly, particularly when smears are prepared and examined by well-trained laboratory personnel . Eight counties in Washington accounted for 72% of all DF cases. The distribution of reported cases by county in Washington differed significantly from the number of stools submitted for examination from these counties. A possible explanation is that stool specimens from the eight counties are routinely sent to the Washington State Public Health Lab (WSPL) when examination for ova and parasites is indicated and stools from other counties are not. In 1985-86 all reported DF diagnoses occurred at the WSPHL. At this time only a few labs in the state, including the WSPHL, reported using the stool collection and examination techniques necessary to detect DF (unpublished data) . In addition, an increased awareness of DF existed among health care providers in San Juan County due to a cluster of cases there, which probably resulted in increased stool spec. submissions. |
Diagnosing parasites |
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"(My) doctor has no
experience in treating (Blastocystis hominis). In fact he says it is so rare
that he hasn't seen or heard about it in 30 years!". NY, USA. Jan. 2006 |
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Need details of specialist labs?
Go
here. "Finally received a result yesterday from the Auckland lab (SCL). The test was positive for Df. The first 2 samples were negative (without a fixative) - despite me driving into town and dropping them off directly to the lab within the hour. Then I supplied another 3 samples in a PVA fixative and the second sample was positive." (May 05)Unfortunately not everyone is given a choice of submitting fixed samples: "My tests came back negative though I am not convinced they were done correctly. My request for the three day liquid suspension was denied by my naturopath who apparently knew better. The guy she had do the testing was an independant who apparently is some kind of expert in this and he doesn't believe the liquid suspension necessary. I fear I wasted $80 odd." (Australia. November 2005)An Australian pathology lab were unfamiliar with both fixative and it's crucial role in diagnosing parasites: "We spoke to a pathologist about the liquid fixative that should be in the stool tests but they had not heard of it before. What exactly is it?" (Australia. November 2005).A Western Australia lab located in Perth had to be educated by a patient about the importance of fixative: "I went to my doctor today and told him that I wanted the tests. I went to my local path collection centre and spoke to the lovely lady to get the fixative. She rang the microbiologist at the Perth lab and he said that I didn't need a fixative. Because I went armed with the relevant printouts of your website re lab testing she was convinced and told the microbiologist that 'the client has quite a lot of information about this and it all indicates that a fixative is needed'. After she found out that they did actually have the fixative (PVA?) in stock she talked him into couriering it out to her collection centre and I pick it up tomorrow! I hope that my specifying a PVA fixative was correct." (September 2007).Access to even basic stool testing might be denied if the treating dr considers B.hominis or D.fragilis harmless: "I've tested positive for Blastocystis Hominis, I even managed to get a treatment with Flagyl but the symptoms remain. When asking for a re-test to confirm if Flagyl worked or not they say that since Blasto probably isn't the cause of my problems, there's no reason for another test. According to them I have already gotten more treatment than they normally give for Blasto, since they almost never treat it... Now I've been prescripted "LuneLax", fibre, since they think I have IBS. Been eating fibre for a month and I can't say it helps...
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No of consecutive |
|
Infections |
1 |
- |
50-60 |
3 |
- |
70-83 |
6 |
- |
90-95 |
10 |
- |
90-100 |
| The Neglected Ameba: D.fragilis A Report of 100 "Pure" Infections B.H.Kean, M.D., & C.L.Malloch, MD Am.J.of Dig.Dis. Vol 11, N o.9, 1966 |
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"Even under ideal circumstances, a single stool specimen is diagnostic only 50% to 60% of the time; three samples increases the sensitivity to 80% and six samples to 95% .
Vol. 18, No. 4 The John Hopkins Microbiology Newsletter.
Monday, January 25, 1999
"As far as the 3-sample rule is concerned it is not 100% accurate. It has been shown to vary depending on the organism but 3 samples are enough to detect 95+% of infections for most of them. That still leaves some undetected of course. I have heard (anecdotally) of someone who had Giardia diagnosed only after 8 samples!" (Parasitologist, London School of Tropical Hygiene and Medicine. 2002)
Parasites do not always show up in stool samples because:
"A number of patients may intermittently shed protozoa in their stool. Similarly, some protozoa (G. intestinalis and D. fragilis) have been shown to have highly variable and intermittent shedding. (van Gool et al., 2003)".
"There is marked fluctuation in the shedding of the parasite from day to day, varying from as high as 17 to 0 per x40 microscopic field. The cystic stages when estimated in 8 Blastocystis-infected individuals ranged from as high as 7.4x10(5) cysts per gram of stool to 0. (Parasitol Res. Vennila GD, et al . 1999 Feb;85(2):162-4)
The number of organisms excreted daily flucuated markedly in the one case investigated. With regard to the distribution of the parasite within a stool, considerably greater numbers were found in the last portion evacuated than in the first half. Dientamoeba fragilis, a review with notes on its epidemiology, pathogenicity, mode of transmissino and diagnosis. Yang & Scholten, Am J Trop Med Hyg. 1977 Jan;26(1):16-22.
Testing too soon after a drug treatment increases the likelihood of a false-negative result because there may not be enough parasites for the lab to identify:
One month after Flagyl treatment only twenty percent of the B.hominis subjects were positive. Six months later the number of positives rose to fifty-three percent. The researchers considered reinfection could explain some, but not all, of the increased detection of this parasite.
A Placebo Controlled Treatment Trial of Bh Infection with Metro.
Nigro. et al. Journal of Travel Med. Vol. 10, No 2.)
The following examples show the limitations of testing three fixed samples:
- M., from the US., suffered with mushy stools, abdominal pain, bloating and cramps. He was prescribed Flagyl — 500mg 3 times daily for 7 days to treat Giardia found in two of three fixed samples. His symptoms returned a few weeks after finishing the treatment.
When another three stool samples were negative, M's GP advised that the problem was advised by his dr that his problem was due to his "system rebalancing itself because Giardia combined with Flagyl is hard on the body".
His symptoms persisted and he was retested. As before, another three fixed samples were negative.
An endoscopy, colonoscopy and CAT scan failed to diagnose the reason for his persistent and ongoing symptoms.
M's had to either accept the possibility that Giardia had caused permanent damage to his digestive tract, or keep on submitting samples to a specialist lab in the hope that something would eventually show why he was still sick.
The expense paid off when Giardia was diagnosed in the next batch of samples.
Based on this result he was prescribed Flagyl in the same dosage and duration as before. Unfortunately this time the drug did not help his symptoms. It seemed likely that the parasite had become resistant. Next he was prescribed five days of Albendazole at 400mg twice daily, followed by ten days of Ornidazole. These treatments made no difference to his symptoms, and M. became concerned that the drugs may have further compromised his bowel flora.
When M's GP advised that he had "run out of options" he decided to consult a naturopath: "The naturopath thinks that I probably still has some parasites combined with a severely disturbed intestinal tract from giardia and all the anti biotics".
Another batch of samples was tested by a specialist lab. Cryptosporidium parvum and Blastocystis hominis were diagnosed. Giardia had disappeared. (US. April '07)
-
A father was concerned about his 12 year old daughter who was reluctant to eat because it caused her stomach pain, gas and an "acid stomach". Her symptoms, which had begun three months earlier, were not improving over time.
D.fragilis, B.hominis, Cryptosporidium were diagnosed in three fixed samples.
His daughter failed to respond to ten days of the anti-parasitic drug Iodoquinol (Yodoxin). Two months finishing the treatment later she was retested and diagnosed with Crypto. Blasto. hominis and D.fragilis had disappeared.
Extensive blood work, an endoscopy and a barium x-ray were negative.
Another batch of samples was tested and this time D.fragilis and Blasto. hominis are identified, but Crypto. had disappeared.
Her symptoms reduced considerably after ten days of Alinia (Nitazoxanide), but within a few weeks she relapsed.
Ten days of Bactrim was prescribed, but a few weeks later even higher levels of Blastocystis hominis were found in her stool samples. Crypto and D.fragilis had disappeared.
Three months after finishing Bactrim the child was still unwell. She also tested positive for Blastocystis hominis and Dientamoeba fragilis. Cryptosporidium had disappeared. (US, September 2006) -
S., from the UK, was "desperate and suicidal" because her stool test results from the London School of Tropical Medicine and Hygiene were negative.
The result was distressing to S. because she had pinned her hopes on specialised stool testing diagnosing two decades of "Severe constipation, intermittent severe fatigue, knawing hungry feeling not relieved with food, feeling faint and weak, bloating and gassy, feeling of toxicity and general malaise & depression". S. had spent at least £20,000 on various alternative therapies trying to find relief from her symptoms.
S. had convinced her GP to arrange for testing with the prestigious London School of Tropical Hygiene & Medicine after finding this site. Her dr had been sceptical because S. had not travelled overseas in recent years, despite S. having suffered with these symptoms since her late teens.
Based on her negative result a consultant at the School of Tropical Medicine in London advised:
"everything was normal. They said that even if the stool samples missed anything, the blood samples would have shows up anything sinister. I did mention that some parasites attach themselves to the wall of the bowel. The consultant looked at me as if I was mad/ hypochrondiac. He was making such statements such as "I see from your medical notes that you have suffered from depression in the past". I understood what he was getting at."
The clinic should have made her aware of the risks of false-negatives due to the problems of irregular shedding. S. was retestd by another specialist lab and was diagnosed with Blastocystis hominis and Dientamoeba fragilis. - Read about B's experience here.
- A US man contacted me about the triple therapy drug treatment which cures more than 85% of Blasto. infections because several antibiotic treatments, including Flagy, had failed to clear Blasto. from the stool samples.
This treatment was the first to have any impact on his symptoms. Unfortunately a few weeks later his symptoms began to reappear, and within a few weeks he was sick again. Three stool samples, tested by a specialist lab four weeks after finishing the meds, were negative.
Determined to find out if Blasto. had survived the treatment F. decided to submit three samples to a specialist lab every month for the next seven months. Unfortunately this man was one of the 15-20% who fail this treatment because Blasto. was diagnosed in the seventh batch.
- A Canadian man contacted in November 2005 about two years of
persistent stomach pain, which at one point became so severe he was admitted to hospital. It was there he was diagnosed with Dientamoeba fragilis.
When two weeks of Flagyl, prescribed by a hospital doctor, failed to relieve his symptoms he underwent an endoscopy, colonsocopy, barium follow through and a lactose test. No abnormalities were detected.
He was prescribed Ciproflaxin, and then Flagyl. Some weeks later he was retested, and when the results were negative Irritable Bowel Syndrome was diagnosed. For this condition he was prescribed the drug Pariet.
This man contacted me for advice about stool testing and I suggested submitting purged samples based on medical literature that Blasto. has a tendency to colonise the cecum — the pouch-like start of the large intestine that links it to the small intestine. He submitted three purged samples to each of two separate labs with this result:
One lab found D.fragilis in one of the three fixed samples. No mention of Dientamoeba fragilis.
The other lab found "a few Blastocystis Hominis and many Dientamoeba Fragilis".
-
N., from the US., suffered with stomach pain, loose bowel movements and nausea for eighteen months. Based entirely on his symptoms, without any stool testing, he was diagnosed with Irritable Bowel Syndrome.
When N. found this site, with its emphasis on specialised testing, he decided to consult a naturopath about stool testing. Testing was arranged and the specialist lab detected Dientamobea fragilis in one of three fixed samples.
A herbal treatment, prescribed by the naturopath, had minimal impact on his symptoms. He decided to retest and submitted purged samples. Here is the result:
"I have just got my stool tests back which showed that I am still infected with D.fragilis and interestingly this test also showed B.hominis. I must point out that I took a laxative called picosulphate to do purged samples to enhance the effectiveness of the tests. Seems to have worked." October 2003. USA. -
D. from Australia, was diagnosed with Blastocystis hominis in 2003. Fourteen days after taking 500mg of Nitazoxanide twice daily for 7 days she was retested. The three samples, tested by a specialist lab, were negative. Despite the negative result she was still not well.
D. assumed she was no longer infected, and that her only option was to control the worst of her symptoms with severe dietary restrictions. After three years of severe dietary restrictions she was retested. To her surprise she discovered that not only that Blasto. had survived, but that she was also infected with D.fragilis.
More examples: -
"Just to let you know, I had the results of my Great Smokies test and I have many D. fragilis bugs. If you remember the London School of Tropical Hygiene & Med. test came back negative."
UK. Feb 2004 -
"After taking a 20 day course of Iodoquinol combined with Doxycycline I have had follow up 2 tests and unfortunately after a clear first test the second shows not only D. fragilis but now Blasto. as well. I'm devastated as it was such a battle tracking down the Iodoquinol here and expensive not to mention time consuming."
-
This woman, determined to discover the cause of her chronic health problems, submitted four batches of samples to Great Smokies over as many months. It's not something everyone can afford to do, but luckily this woman could. Her persistence enabled her to find out why she was sick: "Great Smokies Lab tested me, and Giardia did not show up until the 12th stool sample."
-
A US man submitted six stools samples — two batches of three — to a specialist lab, but the samples were negative. Despite this result his GP suspected Giardia, and prescribed Flagyl. When treatment failed to help the symptoms another three samples were tested by the same lab. The result confirmed the doctor's suspicions — the patient was positive for Giardia.
- A US woman submitted four batches of stool samples to a specialist lab over as many months. Each set consisted of three samples in fixative - for a total of 12 samples. B.hominis showed up in the forth batch.
- A Sydney physician submitted three fixed samples to a specialist lab. The first batch was negative, but a second batch — tested by the same lab a few weeks later — revealed D.fragilis.
- Over a period of twelve months a US couple each submitted three batches of samples to a specialist lab.
Each batch consisted of three fixed samples.
The first two batches were negative. The third batch detected Blasto. in both the husband and wife's samples. Flagyl was prescribed and the wife made a complete recovery. The husand was less fortunate: his symptoms returned some weeks after finishing the treatment and he also tested positive to Blasto. as well as D.fragilis.
- "I had a course of drugs and tests have now come back negative for D.fragilis but positive for Blasto." (US. 2004)
- "Stool testing found high levels of D.fragilis. Three courses of Flagyl later I not only still had D.flagilis I also now had the Blastocystis appear." October 2005
- US woman suffered "extreme fatigue, explosive & very pale colored bowel movements, belching, and a constant bloated feeling". Because she had tested positive to D.fragilis her GP prescribed two courses of doxycline for 10 days, and two 20 day courses of Iodoquinol (Yodoxin). Despite testing negative, she was still unwell. Twelve months later she was referred to an infectious diseases specialist to determine if her symptoms were due to internal damage from the parasite. She was retested and discovered she was still positive for D.fragilis. (December 2005)
- H. returned to the UK, after working in India, with loose stools/diarhoea, gas, chronic fatigue, intermittent headaches, nausea, skin rashes and bowel discomfort and worsening arthritis. Because his GP was "sceptical of testing for parasites" H. had to consult an alternative therapist to arrange comprehensive stool testing. The therapist suspected H. had parasites because of he had become infected with parasites whilst working in India some years earlier. In lieu of testing H. was prescribed an array of herbal treatments, supplements, and probiotics prescribed by alt. therapist did not end H's suffering.
Finally H's GP agreed to arrange stool tests with the London School of Tropical Medicine & Hygiene, who diagnosed Blasto. hominis. The GP was not familiar with this common parasite or how to treat it. Desperate for relief from the disabling symptoms, and lacking any real treatment choices, H. continued on with the expensive course of anti-parasitic and Chinese herbs, immune boosters, vitamin supplements accompanied by a low carbohydrate, sugar, dairy, yeast and nightshade free diet.
"(the treatment) has cost me a fortune, which is all coming out of my savings as I'm unemployed due to my situation, and I'm reluctantly having to accept that it's not having an obvious effect. I just don't seem to be moving forward.".
N. decided to book an appointment with a clinician at the Tropical Diseases Hospital in London. The hospital arranged stool tests with the London School of Tropical Hygiene & Medicine. Despite testing positive to both B.hominis and D.fragilis H. found himself no closer to finding out if these parasites were the cause of his debilitating health problems:
"I had quite an open chat with Dr X about the whole "pathogenically controversial" issue of blasto and d fragilis. He said the Professor's view is that it's probably not pathogenic. He admitted that some people do appear to get better after a treatment of anti-biotics (Flagyl) but said that the School's view is that this is a placebo effect."
(March 2005)
Under reporting of parasites:
Beware — some labs do not report Blasto. even if it is found. The problem exists mainly outside of the US, because US labs are required by law to report B.hominis and D.fragilis to the treating doctor. The problem is more likely to occur in
Canada, the UK, New Zealand and Australia.
Under reporting in Canada was confirmed in the following report:
Not all laboratories routinely searched for B. hominis. The provincial reference laboratory for parasites reported all parasites found in the samples. In only two of the seven other laboratories was this also done. The five remaining laboratories (involving samples from seven day-care individuals) later stated that they did not actively search for, or report, B. hominis as a matter of course because it was not believed to be pathogenic.
BLASTOCYSTIS HOMINIS: A NEW PATHOGEN IN DAY-CARE CENTRES? Canada Communicable Disease Report - Volume 27-09, 1 May 2001
and:
In March 2000, stool samples were collected from 17 symptomatic patients to test for parasites. All patients had at least one of the following symptoms: nausea, vomiting, diarrhoea, abdominal cramps, bloating. Two stool samples were requested for testing at the Provincial Reference Laboratory (a public laboratory in Canada). A further 10 symptomatic individuals were evaluated by their physicians and 2 stool samples from each were sent to 7 different laboratories:
The govt. lab reported all parasites found in the samples, but 5 private labs DID NOT report all parasites, in particular Blastocystis hominis, as they believed this parasite was non-pathogenic and therefore they did not actively search for it. If it was found they did not report it to the treating physician.
B. HOMINIS: A NEW PATHOGEN IN DAY-CARE CENTRES? Canada Communicable Disease Report - Volume 27-09, 1 May 2001
The following are examples of Canadians who were not advised of their infection:
A Canadian man, diagnosed in 2002 with B.hominis, had been treated with a combination of Flagyl, Bactrim and Iodoquinol. A few weeks after this treatment he was retested, and although his samples were negative, his symptoms persisted.
In 2005 he recontacted after discovering that the lab who had tested his samples had made a decision, at the time of his second test, not to include Blasto. in their reports. Believing that he was no longer infected he had consulted 45-50 doctors trying to find out why he was unwell. ( December 05)
C. believed he was giving himself the best chance of finding out if he had parasites when his dr arranged stool testing with a high profile lab in Montreal:
"I specifically asked my doctor if they considered Blastocystis Hominis (the parasite that I suspected) to be a potential pathogen? He said "no" and that they do not even look for it in the samples." (December 2005)
"A microbiologist at the public lab here in Ontario advised me that they will never report blasto when they find it. however, she talked with her supervisor and told me that if my doctor phoned, they would advise him if Blasto was found in my most recent samples." (2003)
Another Canadian, diagnosed with B. hominis, asked a lab. technician attached to a local hospital how often they detect Blasto:
"she said they probably find more than 10-20% of the stool samples contain this parasite but they have only started to report the results since 2001"
(August 02)
Another Canadian infected with Entamoeba histolytica, contacted me in November 2003:
"I won't bore you with all the flagyl misadventures, which are very similar to the stories already on your site. I was treated with the stuff for entamoeba hystolica three times with no success before I found a new doctor who followed the course with 20 days of yodoxin (diodoquin in Canada). Test results finally came back neg for EH. Much rejoicing, until the nurse mentioned, just by the way, there were some other things found that are not considered pathogenic. Suspicious as I was by this point, I asked him for the names of the other things found. This was the first time I had ever heard of blastocystis, and this was a year into my treatment!"
An example from the UK:
"I went to the hospital of Tropical diseases here in London & they said I had nothing. Last week I went to see a specialist in chronic fatigue (as this is what my GP has diagnosed me as having - with no cure) and the specialist Dr. informs me that the hospital have identified BH, but not informed me as they think it is non-pathogenic."
October 2005
Physicians who believe Blasto. is harmless do not always disclose a positive result to their patient:
"I found your site after looking up blastocytis hominis on the computer. I searched for info on BH because my husband was diagnosed with giardia this past March, but they never mentioned BH. It was only when I got a copy of the lab report that I was aware of the infection." (USA. December 2005)
An Australian man, who had tested positive to B. hominis on five separate occasions, was not treated because his doctor did not believe Blasto. was responsible for his bloating, fatigue and nausea. The doctor diagnosed his patient with Irritable Bowel Syndrome and prescribed anti-depressants. The lab who diagnosed Blasto. advised the patient the that their "opposition does not even mention Blasto. to the referring doctor when they find it as they class it non important.". (2005)
Denmark:
A Danish dr was not confident in the ability of Danish labs to diagnose parasites in his patients:
"if one tests here in Denmark, the test normally comes back negative, but if he sends tests from the same person to the USA, the test is often positive. He thinks that (results from) Danish labs often are unusable in this area.".
Alternatives to the current method of diagnosing parasites - microscopy - are thin on the ground. Here are a few:
Rectal swabbing (anoscopy) is another diagnostic technique, and involves scraping inside the rectum area with a small brush, preserving the contents in liquid fixative, and sending the samples for testing to a reputable lab.
The usefulness of this procedure has always been questioned by the wider medical community, yet doctors who use it claim increased detection of parasites because the anoscopy brush dislodges parasites embedded in the bowel wall. Their claims are reflected in the number of people who have written to to tell me they would not been diagnosed if not for anoscopy. Unfortunately many health insurance companies no longer cover this valuable diagnostic procedure, and the cost can be prohibitively expensive for patients:
"I have yet to find a parasite with a purged stool sample sent to Great Smokies yet the rectal swabs have found it 5 times."
"I have had many many stool tests, and non of them have shown the parasites. The only tests that were positive was a rectal swab which showed the cysts of Blasto. hominis and e.histo., an amoeba" (Feb 02.)
"I'm just wondering why the Great Smokies parasite test I did showed no parasites, yet the rectal swab I had done through the doctor in NYC did show the cysts." (Feb. 2003)
"Found blasto. & giardia with an anoscopy in cyst form. I am convinced this is the only valid test for a parasite. Worked for me twice now, when other tests have shown nothing." (2002)
"Results from 3 (fixed) fecal samples tested by Great Smokies Diagnostics, as well as 3 purged samples submitted to Chelsea Biologics, were negative for parasites. However, the samples of an Anoscopy, examined by a parasitologist, revealed: Blastocystic Hominis Cysts" (April 2003)
G. was diagnosed with E.histolytica & giardia by rectal swab after negative results from local labs:
"I have been suffering for more than 20 years. I was diagnosed by a doctor in New York City, Dr. Louis Parish (since retired). He and another doctor had developed a test called a rectal swab. There was a lab tech in the office that looked at the specimen right then and there. He had found Giardia lambia and E. histolytica. (US Dec 2000)
Purging:
A 1986 study (Sheehan et al. Clinical Microbiology) suggests that:
"parasites lodge in the cecum — Intestinal parasites seldom colonize the lower colon, and
therefore, purged stools appear to be more efficient for
finding parasites residing in the cecum. The terminal
portions of stool collected from our purged patients yielded
the highest number of B. hominis organisms, and this finding
suggests that B. hominis has a propensity for cecal colonization,
as does E. histolytica."
This may explain why a number of people have reported testing positive only after submitting purged samples.
Purging, which involves drinking a strong laxative, can force parasites out of the bowel and by doing so increase detection. However, some laxatives can intefere with lab techniques and by damaging the parasite alter its shape, making detection less likely.
Safe laxatives are:
Fleets Phospho-Soda*, Golytely, Nulytely (USA and Canada), Picoprep (Australia), Picosulphate (UK), and Klean-prep (Europe, African and Middle, Far Eastern countries and Canada).
Check with your dr before taking any products which cause diarrhoea.
* Read this information about Fleets before using.
A 1986 study (Sheehan et al. Clinical Microbiology) suggests that:
"parasites lodge in the cecum — Intestinal parasites seldom colonize the lower colon, and
therefore, purged stools appear to be more efficient for finding parasites residing in the cecum. The terminal portions of stool collected from our purged patients yielded the highest number of B. hominis organisms, and this finding suggests that B. hominis has a propensity for cecal colonization, as does E. histolytica."
This may explain why a number of people have reported testing positive only after submitting purged samples.
Purging, which involves drinking a strong laxative, can force parasites out of the bowel and by doing so increase detection. However, some laxatives can intefere with lab techniques and by damaging the parasite alter its shape, making detection less likely.
Safe laxatives are:
Fleets Phospho-Soda*, Golytely, Nulytely (USA and Canada), Picoprep (Australia), Picosulphate (UK), and Klean-prep (Europe, African and Middle, Far Eastern countries and Canada).
Check with your dr before taking any products which cause diarrhoea.
* Read this information about Fleets before using.
Culturing consists of placing a stool specimen in a special media. This media encourages the organism to grow. This method is more time-consuming and therefore more costly for laboratories to perform, and for this reason it is not routinely used:
Although D. fragilis is most commonly identified using permanently stained fecal smears, recent advances in culturing techniques are simplifying as well as improving the ability of investigators to detect this organism. However, there are limitations in the use of cultures since they cannot be performed on fecal samples that have been fixed. Emerging from Obscurity: Biological, Clinical, and Diagnostic Aspects of Dientamoeba fragilis. Eugene H. Johnson, Jeffrey J. Windsor, and C. Graham Clark. Clinical Microbiology Reviews, July 2004, p. 553-570, Vol. 17, No. 3
The following studies also show the value of culturing:
It is important to subculture, even if protozoa are not seen in the primary culture , the first subculture often detects more infections with D. fragilis and Entamoeba species than does the primary culture (Ockert, 1990).
Without culture, we would have overlooked the organism in 2 of 4 infected stool samples. Even so, we probably underdiagnosed the infection by examining only one stool sample from each patient. The number of D. fragilis in faeces can vary widely from day to day. (Desser & Yang, 1976).
Culture contributes even more to the diagnoses of D. fragilis infection . Silard et al (1979) found faecal culture to be more than 5 times as sensitive to microscopy in detecting Dientamoeba and E. histolytica infections, and Ockert (1990) reported still greater i ncreases in sensitivity.
Diagnoses by faecal culture of Dientamoeba fragilis infections in Australian patients with diarrhoea. Nongyao Sawangjaroen, et al. Transactions of the Royal Society of Tropical Medicine and Hygiene (1993) 87, 163-165.
The use of culture techniques may increase detection of D.fragilis signficantly, with reported cases as high as 18.1% in Israel, 36% in Holland and 41.5% in Germany.
Dientamoeba fragilis: the unflagellated human flagellate.
Jeffrey J. Windsor and Eugene H. Johnson.
British Journal of Biomedical Science 1999; 56: 293-306
ELISA (enzyme-linked immunosorbent assay):
A biochemical test named ELISA (enzyme-linked immunosorbent assay) is available for diagnosing Entamoeba histolytica, Giardia and Cryptosporidium. It is considered much more reliable than microscopy because it depends on detecting parasite antigens, in contrast to microscopy which relies on microscopic identification. Because of the cost involved in antigen testing most labs will only carry out this test when a specific request is made by the dr.
The US Centre for Disease Control website contains useful information about specialised ELISA testing. Antigen testing is usually performed on fresh (unfixed) stool.
Antigen test is not yet available for either D.fragilis or B.hominis.
Antibody testing:
Salivary:
Antibodies are produced by the body in response to an infection. Because antibody testing cannot distinguish current infection from past exposure, most doctors do not consider it useful. My view is that until more sensitive and reliable testing is available to diagnose Blasto. and D.fragilis, and because these parasites can cause so much misery to the sufferer, antibody testing has a role for patients who are symptomatic but who have failed stool testing.
Antibody testing is available from Diagnos-Techs, Inc. Because this test is controversial the results are not always accepted by doctors. Example here.
Optimising your results:
The following products may interfere with test results and should be avoided for three weeks prior to, and during, the testing phase:
tetracyclines, sulfonamides, antiprotozoal agents, certain laxatives (see purging below), antacids, castor oil, magnesium hydroxide, barium sulphate, bismuth kaolin compounds, hypertonic salts, mineral supplements, anti-parasitic herbs, antibiotics, antacids, antidiarrheals, enemas, intestinal & radiocontrast agents. Some toilet papers contain chemicals which can interfere with test results.
Always consult your doctor before stopping any medications.
Submit small random samples from the last half, rather than the first half of the stool, because: