|
"Our
results suggests that a single stool specimen examination will miss
many pathogenic protozoan infections in symptomatic persons"
Hiatt
RA, Markell EK, Ng E
American Journal of Gastroenterology 1983 Oct;78(10):634-6
|
"I
am overjoyed to have come across your site. I have just recently
found out that I have D. Fragilis. Ten years ago I was diagnosed
with Irritable Bowel Syndrome, but just recently found out
that I have the bug. This bug has screwed up my life and living
for 10 long years. "
July 04, Canada
"This is a fantastic website. Many thanks. Have just
been diagnosed by a French gastro specialist for DF. My
English GP had no idea, and did not even want to run tests
on stool samples! Keep it up! It is shocking to see
how unprepared the medical community is...and how the USA
doctors simply don't want to admit to this."
e-mailed by G. 17 July 02
(more examples of delayed diagnoses and misdiagnoses here) |
How
many stool samples are necessary to detect D.fragilis?
Because the amount of parasites in the stool varies on a
daily basis at least three samples should be collected on consecutive
or near consecutive days.
This is not the
only criteria for accurate diagnoses but it is a very important
component:
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 |
Since
the number of organisms are reported to vary daily, a series
of stool samples for ova and parasite examination should be
collected.
D.fragilis:
A Gastroeintestinal Protozoan Infection in Adults
Spencer et al
AMJ.,
Vol 77, No. 8. 1977 |
"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 Hygiene
and Tropical Medicine, 2002
Click for examples of "irregular shedding" here. |
|
No
of consecutive examinations
|
|
Infections
revealed % |
|
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, No.9,
1966
|
A
private laboratory found D.F. in two samples. In two public
laboratories, after three tests, the result was negative.
e-mailed by A. from Italy, March 2001 |
Three
samples are not always enough to detect parasitic infections:
"The 3-sample rule 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 Hygiene
and Tropical Medicine, 2002
"In
1993 my husband and 2 year old daughter contracted giardia during
a 3 month trip to Chile. It took about a year to get it diagnosed
as the initial test results were negative"
emailed by DM, March 01
Submitting
PURGED stool samples increases the chances of detection. Click here
for more info.
|
|
"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
S.H.T test can back negative."
|
C. Feb 2004
The importance of liquid fixative:
Dientamoeba fragilis degenerates soon after evacuation, making it almost impossible for the lab to accurately identify the parasite in the stool samples. Fixative keeps the parasites intact making it easier for the lab to see them:
"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."
| Twenty-one patients (6 m, 15 F; 7-78 y) presented with a 2 mth to life-long history of IBS-like symptoms including diarrhoea (2-15 motions/day), constipation, abdominal cramping, bloating, flatulence, nausea, fatigue, anorexia.
Three stool samples from each patient collected in sodium acetate/acetic acid/formalin (SAF) fixative were examined for ova, cysts and parasites. Unfixed stools from the same samples were also examined.
All SAF-fixed stools were positive for Df, while no Df diagnoses were made using fresh stool specimens.
Eradication of Dientamoeba fragilis can resolve IBS-like symptoms
Borody et al. Journal of Gastroenterology and Hepatology (2002) 17 (Suppl.)
|
The lab technician must also be highly experienced in the
identification of D.fragilis:
"Many
laboratory technicians, however, are unfamiliar with the appearance
of this parasite, either living or in stained preparations,
and it is still frequently misdiagnosed as an amoeba. Furthermore,
degenerating forms become motionless and full of small vacuoles
which coalesce into a single large vacuole surrounded by a thin
layer of protoplasm containing the two nuclei: such forms bear
a striking resemblance to Blastocystis."
Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 94(5),Sept./Oct.
1999: pp 611-613
Intestinal Parasites of Some Diarrhoeic HIV-Seropositive Individuals
in North Brazil
The proper collection and preservation of multiple stool
specimens in addition to adequate microscopic examinations by
qualified, trained individuals are necessary for the identification
of D.fragilis.
Spencer et al: Am.J.of Gastro.
1982
|
Because
diagnostic parasitology, especially protozoology, is
perhaps on the of the most difficult of all routine
lab. investigations and because competence to accurately
diagnose parasitic infections is not easily obtained
(as has been emphasized by the Am. Acad. of Paed., the
World Health Org., and others), physicians should perhaps
be more concerned about the competence of the labs.
to which they submit samples and be better informed
of techniques used routinely by the laboratory before
accepting positive or negative reports at face value.
It may well be that many cases of abdo. distress of
hitherto unknown etiology are, in fact, due to D.fragilis.
AYang & Scholten,
Am. Journal of Trop. Med. & Hygiene.
Vol 26, No 1. 1975
|
|
Reports of
D.fragilis continues to grow in the UK because more labs are using
specific techniques to find this parasite. However, the majority
of labs do not look for D.fragilis:
The
laboratory reports of the Communicable Disease Surveillance
Centre show that in 1992, 68 cases of D fragilis infection
were reported from seven laboratories and that by 1996 this
figure had increased to 231 cases reported from 20 laboratories
(unpublished data). These results reflect an increase
in the number of laboratories performing faecal stains.
It can be assumed, however, that the true incidence of D
fragilis infection is many times higher: there are
an estimated 450 diagnostic laboratories in the United Kingdom,
most of which do not look for this pathogen.
Letter to BMJ 1999; 318:735 (13 March 1999)
J
J Windsor, Senior biomedical scientist & E H Johnson,
Associate professor.
|
Unfortunately accurate diagnoses is only one half of the battle. Finding
a specialist or doctor who is familiar with the most effective treatments
is the other half::
" I am very tired of the gastro and
family doctors telling me there is no need to treat these parasites and
that I should "live with it"
Posted on the message
board by
Ruti, June 29, 2002
The
parasite D.fragilis is believed to be uncommon in western countries.
In fact published surveys show that when specific stool collection
and testing methods are used, and the samples are examinined by
highly skilled lab. personnel, Dientaomeba fragilis is found more
frequently than Giardia:.
Generally
considered rare and either not found in surveys, or recovered
in small proportions only, we have, since the adoption of a
two bottle collection kit for faecal samples, found it almost
as common as Giardia lamblia
D.Fragilis: A Review
with Notes on its Epidemiology, pathogenicity, mode of transmission
and diagnosis by Yang & Scholten (1976)
Although DF is
thought to be uncommon, surveys indicate that it's occurrence
is worldwide. In properly collected and preserved stool specimens
examined by lab. personnel trained to recognize this flagellate,
the incidence of this organism corresponds to that of Giardia
lamblia. It is particularly important that permanently stained
slides of stool specimens in addition to adequate microscopic
examinations by qualified individuals are necessary for the
identification of DF.
Dientamoeba fragilis - an intestinal pathogen in childre?
(Am J Dis Child 133:390-393, 1979) |
Published
research:
Because the
time during which this organism remains in a recognisable condition
in stools is limited, samples must be examined shortly after
defecation, or be bulk-preserved in a suitable fixative immediately
after a bowel movement.
Yang & Sholten, Am.J.
TM&H Vol 26, No.1
1975
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 increases
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.
extract from: Dientamoeba fragilis: the unflagellated human flagellate
Jeffrey J. Windsor and Eugene H. Johnson
British Journal of Biomedical Science 1999; 56: 293-306
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.
DIENTAMOEBA FRAGILIS; A GASTROINTESTINAL PROTOZOAN
INFECTION IN ADULTS. Mary J. Spencer, M.D., Martha R. Chapin, R.N.,
and Lynne S. Garcia, M.T.(ASCP) Am. Journ. of Gastro. Vol. 77. No.
8, 1982
Diagnosis is best made by finding the characteristic trophozoite
on a permanently stained faecal smear as it is not reliably detected
on direct wet prep. microscopy or a faecal concentrate ......Patients
collect their stool specs. at home into polyvinyl alcohol
fixative to ensure that there is minimal degeneration of the protozoan
while the spec. is being transferred to the lab. Three specs. are
collected on different days to increase the chance of detecting
intermittent excretion of the protozoan.
DF: A BOWEL PATHOGEN? Oxner, Paltridge, Chapman, Bramwell
Cook, Sheppard. New Zealand Med. Journal. 11 Feb. 1987. p 4-65
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.
The Neglected Amoeba: Dientamoeba fragilis. A Report of 100 "Pure"
Infections
B.H. Kean, M.D., and C.L. Malloch, M.D. Am.Journal of Digestive
Diseases. New Series, Vol.11 No.9 1966
The prevalence of D fragilis
in most localities is poorly documented, as the methods commonly
used in intestinal parasite surveys are unsuitable for detecting
trophozites. Reported rates vary from less than 1%
to more than 5% (Yang and Schulten, 1977)......
In a semi-communal group in California Dientamoeba fragilis
was the most frequently diagnosed intestinal protozoan — 76%
of 138 children, and 56% of 82 adults
(Millet et al 1983) FLAGELLATE PROTOZOA OF THE DIGESTIVE
AND UROGENITAL TRACTS Clinical Parasitology, 9th Ed. Beaver, Jung
& Cupp 1984
Sampling and detection methods may have an immense influence on
the ability of a laboratory to detect D.fragilis. An increased
sensitivity of 31.1% was described when three faecal samples were
examined, rather than a single one.
Grendon et al reported a five-fold increase
in detection when all stools are suitably stained, compared with
only the loose and watery specimens.
Dientamoeba fragilis: the unflagellated human flagellate
Jeffrey J. Windsor and Eugene H. Johnson
British Journal of Biomedical Science 1999; 56: 293-306
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.
DESCRIPTIVE FEATURES OF DIENTAMOEBA FRAGILIS INFECTIONSJ.H. GRENDON,
R.F. DiGIACOMO
& F.J. FROST Journal of Tropical Med & Hygiene 1995, 98,
309-315
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.
DF: A REVIEW WITH NOTES ON ITS EPIDEMIOLOGY, PATHOGENICITY, MODE
OF TRANSMISSION AND DIAGNOSIS (J. Yang & T H Scholten, Journal
of Tropical Medicine and Hygiene, Vol 26, No 1)
Unreliable
identification of D.fragilis may explain variations in the results
of different studies. Even in stained faecal smears, which
must be prepared from fresh material (Ockert, 1990), Dientamoeba
may be confused with amoeboid forms of Blastocystis, Endolimax and
other organisms, or degenerated polymorphonuclear leucocytes.
(Markell et al., 1986; Ash & Orihel, 1990.) Nongyao Sawangjaroen,
et al. Trans of the Royal Society of Tropical Medicine and Hygiene
(1993) 87, 163-165.
"The prevalence
of D. fragilis in most localities is poorly documented, as the methods
commonly used in intestinal parasite surveys are unsuitable for
detecting trophozoites"
J.Clinical Parasitology 9th Ed. Beaver, Jung & Cupp
1984
More testing info. on IBS
- a misdiagnoses?
|
