Artifacts Definition Artifacts other things living or artificial present in the stool that are not parasites and could mislead the laboratory worker Note Artifacts not to be mistaken for cysts ID: 631232
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Medical Parasitology Lab
ArtifactsSlide2
Definition Artifacts:
other things, living or artificial, present in the stool that are not parasites and could mislead the laboratory
worker.
Note:
“Artifacts not to be mistaken for cysts”.Slide3
BlastocystisRound or oval, sometimes with angular irregular edges, contain one large vacuole taking up almost the whole cell, the compressed cytoplasm forms a granular ring round it.Slide4
BlastocystisSlide5
Yeast Oval, often with buds, often contain eccentric cluster of 3-6 small granules.
Some related forms of yeast are rectangular, with a very clear oval cytoplasm inside:
arthrospores
.Slide6
Yeast Yeast in an iodine-stained concentrated wet mount of stool. Yeast in wet mount may be confused for Giardia lamblia
cyst.
Yeast
Giardia lamblia
cystSlide7
Leukocytes Round or slightly elongated, with an irregular outline.Contain refractile cytoplasm, clear and granular with tiny vacuoles.
Nucleus indistinct, sometimes with a star- shaped false
karyosome
. Slide8
Pus Pus can be seen by the naked eye as opaque, greyish streaks ( not transparent like mucus).
Under the microscope it appears as a mass of more or less degenerate leukocytes Slide9
Bacteria Slide10
Coccidia These are protozoa that may be parasite of men without causing any significant pathogenic effects, or may be found in transit in stool following the consumption of infected foods.
They appear in stool in a form resembling cyst called
oocysts
or
sporocysts
.
An elongated oval, sometimes tapered at one pole.
There three types:
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sporozoites
(small banana shaped rods), each containing a small round nucleus, sometimes a few large granules massed at one pole.
One large round granular cell.
Refractile
granules completely fill the interior. Slide11
Coccidia (cont.) Slide12
Coccidia (cont.) Slide13
Air bubblesSlide14
Oil droplet Slide15
Fungal spores Fungal spore in a wet mount of stool. Such spores may be confused for the cysts of Entamoeba
spp
.
Fungal spore
Entamoeba histolytica/dispar
cystSlide16
Plant fiber Slide17
Strongyloides stercoralis larvae Slide18
Misdiagnosis can lead to improper treatmentSlide19
Hair fiberSlide20
Plant cellMay confused with helminthes eggsSlide21Slide22
Plant cell
Plant material in an iodine-stained concentrated wet mount of stool.
This material can be confused for a hookworm eggSlide23
Charcot-Leyden crystalsSlide24
Epithelial cellsSlide25
Macrophages Slide26
RBCsSlide27
Pollen grainsSlide28
Pollen grainsSlide29
Starch granules Slide30
Crystals Slide31
Non- parasitic structure found in stoolNon parasitic objects may be misidentified as parasites. The differentiation of the most common pseudoparasites is as follow:
Protozoan cyst
: may be confused with air bubbles, fat globules or yeasts.
Iodine should be added to the wet preparation so that the internal structure of the cyst is stained and identifiable.
Amoebic trophozoites:
must be differentiated from non- pathogenic protozoan trophozoites and macrophages.
Trophozoites of
Entamoeba histolytica/dispar
must be motile and
hematophagus
.
Macrophages found in cases of intestinal
amoebiasis
are distinguishable from amoebic trophozoites by possessing a larger nucleus and, although they can
haematophagus
, they are only motile for a very short time. Their pseudopodia are small, blunt and granular. Slide32
Cont. Ova, their general shape, except for Entrobius
, is perfectly symmetrical, distinguishing them from various objects found in stools.
Trichuris
and
Taenia
ova may be confused with pollen grains.
Ascaris
ova may be confused with vegetable cells, the latter having smooth, thick walls but irregular shape.
Strongyloides
or hookworm larvae can be confused with hair or vegetable fibers. The latter are usually tapered at one end and the other being blunt and with no internal structure.
Free living nematode larvae may be found in concentrates if contaminated water is usedSlide33
Fasciola ova resemble vegetable cells.Insect and may be found in stools as spurious infection. Mite eggs may be confused with hookworm eggs. Dipylidium caninum eggs sacs can look similar to vegetable cells.
Other structure found in stool are crystals, Charcot- Leyden are the breakdown products of
eosinophil
cells and may be present in stools or sputum.
Starch granules are sometimes seen in stool. When undigested, they appear as concentric rings and stain blue with iodine, when partially digested, they stain red.
Cont.
Slide34
Intestinal Protozoa Raed Z. Ahmed, Medical Parasitology Lab.,2012
Giardia lambliaSlide35
Giardia lambliaIt is the most common flagellate of the intestinal tract that cause giardiasis, Traveler's diarrhea.
There is two diagnostic stages for Giardia lamblia :
Cyst
is oval measuring 11
–
14u
in length and 7 to 10 µm in width
with
4
nuclei and remnant flagella,
and it’s the infective
stage.
Trophozoite
is
described as having a 'tear-drop' shape and are 10 to 20 µm long and 5 to 10 µm wide. The trophozoites contain two nuclei, four pair of
flagella. (motility
by flagella).
Diagnosis:
Stool examination to see cyst stage, or trophozoite stage if the sample is fresh.Slide36
Life cycleSlide37
Giardia lamblia cystSlide38
Giardia lamblia cystSlide39
Giardia lamblia Trophozoite Slide40
Giardia lamblia Trophozoite