Medical Parasitology Lab.

1
Medical Parasitology Lab.

• Artifacts

2
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.

Raed Z. Ahmed, Medical Parasitology Lab.,2012
3
Blastocystis

• Round 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.

Raed Z. Ahmed, Medical Parasitology Lab.,2012
4
Blastocystis
Raed Z. Ahmed, Medical Parasitology Lab.,2012
5
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.

Raed Z. Ahmed, Medical Parasitology Lab.,2012
6
Yeast
Giardia lamblia cyst
Yeast
Yeast in an iodine-stained concentrated wet mount
of stool. Yeast in wet mount may be confused for
Giardia lamblia cyst.
Raed Z. Ahmed, Medical Parasitology Lab.,2012
7
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.

Raed Z. Ahmed, Medical Parasitology Lab.,2012
8
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

Raed Z. Ahmed, Medical Parasitology Lab.,2012
9
Bacteria
Raed Z. Ahmed, Medical Parasitology Lab.,2012
10
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
• 4 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.

Raed Z. Ahmed, Medical Parasitology Lab.,2012
11
Coccidia (cont.)
Raed Z. Ahmed, Medical Parasitology Lab.,2012
12
Coccidia (cont.)
Raed Z. Ahmed, Medical Parasitology Lab.,2012
13
Air bubbles
Raed Z. Ahmed, Medical Parasitology Lab.,2012
14
Oil droplet
Raed Z. Ahmed, Medical Parasitology Lab.,2012
15
Fungal spores
Fungal spore
Entamoeba histolytica/dispar cyst
Fungal spore in a wet mount of stool.  Such
spores may be confused for the cysts of Entamoeba
spp.
Raed Z. Ahmed, Medical Parasitology Lab.,2012
16
Plant fiber
Raed Z. Ahmed, Medical Parasitology Lab.,2012
17
Strongyloides stercoralis larvae
Raed Z. Ahmed, Medical Parasitology Lab.,2012
18
Misdiagnosis can lead to improper treatment
Raed Z. Ahmed, Medical Parasitology Lab.,2012
19
Hair fiber
Raed Z. Ahmed, Medical Parasitology Lab.,2012
20
Plant cell
May confused with helminthes eggs
Raed Z. Ahmed, Medical Parasitology Lab.,2012
21
Plant cell

• Plant material in an iodine-stained concentrated
  wet mount of stool.
• This material can be confused for a hookworm egg

Raed Z. Ahmed, Medical Parasitology Lab.,2012
22
Charcot-Leyden crystals
Raed Z. Ahmed, Medical Parasitology Lab.,2012
23
Epithelial cells
Raed Z. Ahmed, Medical Parasitology Lab.,2012
24
Macrophages
Raed Z. Ahmed, Medical Parasitology Lab.,2012
25
RBCs
Raed Z. Ahmed, Medical Parasitology Lab.,2012
26
Pollen grains
Raed Z. Ahmed, Medical Parasitology Lab.,2012
27
Pollen grains
Raed Z. Ahmed, Medical Parasitology Lab.,2012
28
Starch granules
Raed Z. Ahmed, Medical Parasitology Lab.,2012
29
Crystals
Raed Z. Ahmed, Medical Parasitology Lab.,2012
30
Non- parasitic structure found in stool

• Non 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.

Raed Z. Ahmed, Medical Parasitology Lab.,2012
31
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 used

Raed Z. Ahmed, Medical Parasitology Lab.,2012
32
Cont.

1. Fasciola ova resemble vegetable cells.
2. Insect and may be found in stools as spurious
   infection. Mite eggs may be confused with
   hookworm eggs.
3. Dipylidium caninum eggs sacs can look similar to
   vegetable cells.
4. Other structure found in stool are crystals,
   Charcot- Leyden are the breakdown products of
   eosinophil cells and may be present in stools or
   sputum.
5. 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.

Raed Z. Ahmed, Medical Parasitology Lab.,2012
33
Entamoeba histolytica/ dispar

• Intestinal Protozoa

Raed Z. Ahmed, Medical Parasitology Lab.,2012
34
Entamoeba histolytica/ dispar

• E. histolytica inhabit large intestine and cause
  amoebic dysentery.
• There is two diagnostic stages for E.
  histolytica/ dispar
• Cyst is regular round measuring measure 10 20u
  in diameter with 4 nuclei, and its the infective
  stage.
• Trophozoite is the motile form, measure 15-20u in
  diameter with large nucleus. (motility by
  pseudopodia).
• Diagnosis
• Stool examination to see cyst stage, or
  trophozoite stage if the sample is fresh.

Raed Z. Ahmed, Medical Parasitology Lab.,2012
35
Life cycle
Raed Z. Ahmed, Medical Parasitology Lab.,2012
36
Entamoeba histolytica/ dispar Cyst
Raed Z. Ahmed, Medical Parasitology Lab.,2012
37
Entamoeba histolytica/ dispar Trophozoite
Raed Z. Ahmed, Medical Parasitology Lab.,2012