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Quick
links:
Optimal testing for parasites
The problem of intermittent shedding
Rectal swabbing (anoscopy)
Growing parasites in the lab from your samples can increase detection
Testing after treatment:
Optimise your stool tests (More info.
about optimal testing also available on the Dientamoeba
fragilis lab testing page)
Travel & parasites
Blasto's
ability to cause symptoms has been questioned by the medical establishment
since its discovery in the early 1900s. Sufferers are often advised
that their infection is not causing their symptoms:
"My
GP was sceptical of me having a test (for parasites) in the
first instance, and when Blastocystis showed up he said he'd
never even heard of it!"
January 2005 - UK
Blastocystis
hominis may be the most common parasitic infection of humans.
This organism is often missed on stool examination but grows
luxuriantly in all the media used to cultivate xenic Entamoeba.
Establishing
Cultures of Entamoeba in vitro
London School of Hygiene & Tropical Medicine 2000 |
As
B.hominis is the most common faecal parasite seen at both Aberystwyth
PHL and Swansea PHL in the UK, we feel that the CDSC figures
do not reflect the true incidence of B.hominis in England and
Wales. Indeed, all 139 reports of B. hominis reported to CDSC
Wales in 2000 were detected by our two laboratories (unpublished
data). We believe that this can be attributed to laboratory
awareness and the use of suitable methodologies.
JJ Windsor, et
al
British Journal of Biomedical Science 2001; 58: 129-130 |
A
study carried out at the London School of Hygiene and Tropical Medicine
in 2001 found the incidence of Blasto. was more than 40% in those
diagnosed with Irritable
Bowel Syndrome. (unpublished data).
"It
took us four years to finally convince medical doctors to test
our 30 year old daughter for parasites with a lab that was more
reliable than the traditional quick stool sample (which just
showed her with "non-pathogenic entameobacoli cysts".
We finally tested her with the ELISA Test at the Diagnos-Techs
Lab in Kent, Washington, near Seattle. It requires several stool
samples on different days, plus some saliva samples, and is
proported to be 99% accurate. Bingo! It showed her with Giardia,
Candida overgrowth, Toxyplasmosis, and Blasto."
received December 2004 - USA |
Optimal testing for
Blastocystis hominis
Medical literature shows that detection
of Blastocystis hominis increases significantly when three fecal
samples, collected in jars which contain liquid fixative. According
to medical literature three samples are 70%
- 83% accurate.
The fixative prevents morphological changes once the parasite leaves
it's host. These changes can render the parasite unrecognisable
by the the lab, resulting in a false-negative.
Accurate
identification of Blastocystis hominis requires special laboratory
staining methods. These stains are not routinely used by Australian
or UK laboratories:
Over a one-year period, 1390 faecal samples were submitted to
Aberystwyth Public Health Laboratory for routine microbiological
examination. All were stained using a commercial trichrome method.
Blastocystis hominis was detected in 96 (6.9%), making it the
most common parasite found in the study. Of the B. hominis-positive
specimens, 73% were missed on direct microscopy.Molecular typing
of B. hominis has revealed extensive genetic diversity in morphologically
identical strains and thus detection by microscopy alone may
not be sufficient to confirm the role of this organism in human
disease.
Br J Biomed Sci 2002;59(3):154-7
Incidence of Blastocystis hominis in faecal samples submitted
for routine microbiological analysis. Windsor JJ, Macfarlane
L, Hughes-Thapa G, Jones SK, Whiteside TM. |
Participating
and referee laboratories failed to authenticate Blastocystis
hominis as the correct answer (86 and 80%) so all answers were
accepted. Quality control examination of 4% of this sample showed
one cyst per every 3-5 oil fields. Staining quality was variable
which may have led to the high number of labs reporting "No
Parasites Seen".
NEW YORK STATE PARASITOLOGY PROFICIENCY TESTING PROGRAM 07
OCTOBER 2002
NYS Dept of Health. |
"Great
Smokies* / USA did not find the Blasto. In the Turkey lab. it
took them 10 minutes. During 3 days those people tested 3-4
times, all positive."
R. (USA - travelled to Turkey for further testing)
July 2004
Please note that the statement above is not a reflection
on Great Smokies Labs. Testing at reputable labs is no guarantee
the parasite will show up at the time of testing. A 1966 study
on previously diagnosed infections with Dientamoeba fragilis
found three samples is diagnostic 70-83% of the time. Ten samples
is 90-100% diagnostic. (Kean & Malloch, 1966). For more info.
see "intermittent shedding"
" I sent stool samples to Quest Diagnostics (a huge laboratory
chain in the US that most medical doctors use) and to a parasitologist**,
samples taken from THE SAME BOWEL MOVEMENTS and the private
parasitologist found blasto and Quest found nothing"
received 21 Oct 2002 |
For those who wish to rule out parasites as a cause of their symptoms
specialised testing can be prohibitively expensive:
"I had to pay £225 to have my tests done. That's a lot of money"
from a UK resident - tested by a private lab (June 03).
Although
the results of three fixed samples, tested by an experienced laboratory
is more reliable than results of a single sample tested, there are
other important factors which contribute to misdiagnosis: One is
the problem of intermittent sheddingof the parasite in fecal samples
(see below); another is misreporting by
labs.
STOOL
CULTURING:
Culturing
(allowing the parasites to grow in samples over a number of days)
can increase detection dramatically, as the study below shows. Ask
your lab if they culture samples.:
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Over
900 fresh stool specimens, from soldiers in the Royal Thai
Army, were each checked for the parasite using three methods:
simple smears; formalin-ethyl-acetate concentration; and cultivation
in Jones' medium. Although 334 of the samples were found
to be culture-positive, the parasites were only detected in
142 of the simple smears, and faecal concentration led to
an even lower sensitivity (64 positive samples)In-vitro cultivation
does seem worthwhile in the detection of B. hominis carriage
in field studies.
Ann Trop Med Parasitol. 2002 Dec;96(8):803-7.
In-vitro cultivation: a sensitive method for detecting Blastocystis
hominis.
Leelayoova S, Taamasri P, Rangsin R, Naaglor T, Thathaisong
U, Mungthin M. (Thailand)
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Further
info. on increased detection rates when culturing here
The
problem of intermittent shedding:
The
number of parasites present in fecal samples fluctuates widely on
a daily basis. On some days the number of parasites excreted in
feces may be too low for detection by lab technicians. Many of those
with Blasto. who contact this site, as well as the author of this
site, have experienced alternating negative and positive results
due to intermittent shedding.
Three
samples is diagnostic 70-83% of the time.
Ten samples is 90-100% diagnostic. (Kean & Malloch, 1966).
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Examples
of intermittent shedding:
B., from the UK, was diagnosed with Blasto. hominis. Over
two years she tried a number o different drug treatments.
After each treatment she tested positive for Blasto. After
the last treatment, a combination of the drugs Furazolidone,
Secnidazole and Nitazoxanide, Blasto. disappeared for a total
of 8 months. Because of ongoing, albeit reduced symptoms,
B. was tested a total of seven times, each batch comprised
3 stool samples collected in liquid fixative and tested by
a with a reputable lab. Blasto. hominis showed up in the seventh
batch. Some of the previously negative samples had been
purged.
"Symptoms described on your web page have persisted for
three years, even though I have been treated with several
doses of metronidazole. The parasites didn't show up in the
first stool samples, which were repeated FIVE times. Finally
the did show up, but treatment has failed to iradicate symptoms."
PR, 3/03/04
"Blasto. hominos was only found in my child after 8 fecal
samples were tested. We were very lucky our present dr was
willing to look for parasites, as the previous dr insisted
my son had an irritable bowel which would clear up in time."
B., Jan 2004 (USA)
"I
have been tested for parasites several times, but it was yesterday
that they came up with the diagnoses: Blastocystis hominis."
A.M., 7 May 2002
"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."
M. October 2003
(submitting purged samples helps increase detection - info.
here)
"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 can
back negative."
C. Feb 2004
"Great Smokies Lab tested me, and Giardia did not show
up until the 12th stool culture."
Another woman tested positive to Giardia in the 12th stool
sample. She also tested positive to Blasto. only after
finishing tinidazole for Giardia!
A US woman was tested "many times". Blastocystis
hominis showed up in the 12th stool sample of the fourth batch
samples sent for testing to a reputable lab.
A Sydney doctor tested positive to D.fragilis in the second
batch of samples tested a reputable Sydney lab. The first
batch of samples, 3 weeks previousy, were negative.
A husband and wife tested 3 times by a reputable lab (ie they
submitted 9 samples over 12 months). All samples positive
for Blasto.. After drug treatment Blasto. has disappeared
and D.f. was detected.
Another person tested positive to Blasto. hominis in the fourth
set of tests (ie a total of 12 samples were tested).
The samples were tested by a lab highly skilled in detection
of this parasite.
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The
shedding pattern of the vacuolar and cystic forms of Blastocystis
hominis in infected individuals have been shown in the present
study to be irregular.
The study shows that 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.
The shedding of cystic and vacuolar forms observed
over a period of 20 days in experimentally-infected Wistar rats
were not only shown to be irregular but the amount varied from
host to host. The study has important diagnostic implications
in that the stool samples must be collected more than
once from patients showing clinical signs and symptoms to eliminate
the cause of it to Blastocystis. The study also shows that there
are asymptomatic individuals who pass a large amount of cysts
as such individuals should be treated to prevent transmission
to others.
Irregular shedding of Blastocystis hominis.
Parasitol Res 1999 Feb;85(2):162-4
Vennila GD, et al |
Occasionally
the patient showed alternatively positive and negative results
in stool examinations.
Clinical significance of B.hominis infection
Am.J of Gastro. 1989 |
See "Medical Misdiagnoses"
for more examples of intermittent shedding.
Rectal Swabbing (Anoscopy)
Another method of parasite detection is, anoscopy or rectal
swabbing. This technique involves scraping inside the rectum area
with a small brush, preserving the contents in liquid fixative,
and sending the samples to a reputable laboratory for testing.
Anoscopy is claimed by doctors who use it to be far superior in
the detection of Blastocystis hominis when combined with stool
sampling. The number of doctors who use this method are few
and it's effectiveness as a technique for diagnosing parasites is
generally disputed by medical experts. However, there have been
a number of reports to this site of people who tested positive to
Blastocystis hominis and other parasites only by this method:
Examples of diagnoses by anoscopy (rectal swabbing):
Karen was tested by Great Smokies Diagnostics (a reputable private
lab) and by her doctor's local lab. All samples were negative. She
wrote:
"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."
Karen was retested a number of times due to failure of a number
of drug treatments to relieve her symptoms.
L
was diagnosed was diagnosed with Blasto. and E.histolytica via rectal
swab:
" 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. hominus and e.histo., an amoeba"
(Feb 2002).
Susan was diagnosed with Blasto. cysts via anoscopy:
"I'm just wondering why the GS 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)
Mary wrote:
"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."
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, studied by a parasitologist,
revealed: Blastocystic Hominis --- Cysts Found 2+
(M., April 2003)
G.
was diagnosed with E.histolytica & giardia by rectal swab after
negative stool tests:
"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. (Dec 2000)
Testing after treatment:
Drug treatment may reduce the number of parasites down to a level
too low for detection at the lab. This problem was highlighted in
a placebo controlled study ( Nigro L. et al. April 2003). Subjects
with Blastocystis hominis were treated with metronidazole. Twenty
percent of the metro. treated subjects were B. hominis positive one
month after treatment. At six months this figure had risen to 53%.
The authors considered reinfection may be a factor, but unlikely
to be the sole reason for Blasto's reappearance.
The
author of this site experienced false negatives due to intermittent
shedding. After testing positive for D.fragilis 1994, many samples
tested between 1994 and 2001 were negative for D.fragilis. In 2001
three fixed samples tested by a parasitologist revealed not only
D.fragilis but also Blasto. After taking Iodoquinol and doxycycline
to treat the D.fragilis three fixed samples were again negative
for both parasites. Approximately three weeks later three purged
samples were submitted. Blasto. showed up but D.fragilis did not.
Laboratories and misreporting
Not
all laboratories report the presence of Blastocystis hominis (read
more examples below).
| "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." |
Although
US labs are now required by law to use the specific tests necessary
for detection of Blasto. hominis and Dientamoeba fragilis, and to
report their presence when found, this is not the case in many other
countries.
The majority Australian, New Zealand, Canadian, UK and labs in other
European countries do not employ the specific types of testing methods,
nor do they employ technicians skilled in the detection of these
parasites. Many of these labs do not report the presence of Blasto.
hominis when detected in stool samples.
Speicalised testing is not routinely used for patients with digestive
disorders. The majority of those with digestive symptoms are misdiagnosed
as suffering from Irritable
Bowel Syndrome.
| "I
asked my doctor for B. hominis and D. fragilis testing, she
thought I was crazy and refused.".
(received from woman with chronic digestive disorders, USA,
2003) |
An
example of inadequate stool collectiona & testing methods followed
by ineffective treatment, due to ill-informed medical advice:
Anders, from Sweden, was a victim of poor lab. techniques. Three
years after a trip to Asia and Australia his chronic digestive problems
were diagnosed by a specialised labs with Blastocystis hominis and
Dientamoeba fragilis. Specialised labs employ specific types of
stool collection and testing methods, advised in medical literature,
necessary for accurate diagnosis of Blastocystis hominis and Dientamoeba
fragilis.
Although Anders' doctor did not believe the parasites could be the
cause of his symptoms, he prescribed 10 days of Flagyl (600mg 3x
daily) in case there was another undetected "bug". This
approach is common in doctors who do not believe in the pathogenicity
of either D.f. or Blasto. hominis.
Many doctors believe that that Flagyl is the "gold standard"
treatment for bowel infection. This theory is not supported by published
literature.
Ander's symptoms had not changed at the end of treatment, and a
single stool sample tested locally was negative for either parasites.
However, Anders' was more knowledgeable than his doctor about the
need for specific stool testing, and pursued further testing through
a Swedish lab. who used the recommended detection methods. The result:
three stool samples, collected in fixative, were positive for
both parasites.
Anders is now trying to convince his doctors of the need for specific
therapy for Blasto. and D.fragilis.
(Jan 2004)
Anders story is not unique. Following are examples of non-reporting
of Blastocystis hominis by labs:
S.,
a Blasto. sufferer, asked the lab. technician of a large Canadian
hospital if they regularly find Blasto: " she replied that
probably more than 10-20% of the stool samples contain this parasite
but that they have only started to report the results since last
year!"
sent by S. 5 August 02
M. tested positive five times for Blasto. in recent years by a lab
in Brisbane, Australia. They confided that the opposition path.
lab " does not even mention Blasto. to the referring doctor
when they find it as they class it non important." Her positive
test was not much help to M. as her doctors do not believe the Blasto.
is the cause of her symptoms of bloating, fatigue, nausea and
irritable bowel. Her physician considered her symptoms resulted
from depression and a anxiety disorder. She was prescribed anti-depressants
meds.
R.
is a Canadian infected ith the parasite Entamoeba
histolytica. In November 2003 he contacted the author of this
site:
"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 no 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!"
Failure to report the presence of Blasto. was documented by the
Canadian Centre for Disease Control in 2001:
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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
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Your
tests
If you haven't already done so, ask your doctor to test you for
parasites using three samples preserved in liquid fixative. If your
doctor will not agree, the labs listed on the help
page use the specific stool collection and testing methods necessary
to detect both Blasto. and D.fragilis. If you are having problems
finding a dr willing to help contact
the author of this site for advice.
NOTE: Parasites adhere to the bowel. Using a special laxative helps
force parasites out of the bowel and increases the detection rate.
Purging info. available here
(More info. on testing for parasites is also available on the D.fragilis
section of the site)
TRAVEL
& PARASITES:
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"It
was not necessary
to travel to acquire the organism."
Epidemiology
& Pathogenicity of Blastocystis hominis,
J.Clin. Micro. by Doyle et al in 1989
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Parasites
are often not considered unless there is a history of travel to
tropical or developing countries.
"Doctors always ask if you have been out of the U.S., and if
you haven't they don't think you can have anything."
received from D. (2002)
( more examples of "Medical
Mismanagement")
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