Parasitiology Exam 2

Stool O&P looks for

Ova (EGGS)

Parasites (not eggs)

Entamoeba histolytica trophozoite

- erythrophagocytosis

- Single nucleus: Central karyosome and Peripheral chromatin

- 15-20 um

Entamoeba histolytica cyst

- Chromatid body with blunt rounded ends

- 4 nuclei

Entamoeba coli trophozite

1 nucleus w/eccentric/large karyosome

Dirty/vacuolated cytoplasm

15-50 um

Entamoeba coli cyst

8+ nuclei (the only one w/>4)

Eccentric karyosome

10-35 um

Entamoeba hartmanni trophozoite

5-15 um, small/compact karyosome

Entamoeba hartmanni cyst

Smaller (5-10 um) but like E. histolytica

Small chromatid bodies

Endolimax nana trophozites

6-12 um, single nucleus

Irregular “blot-like” karyosome

Cytoplasma granular & may be vacuolated

Endolimax nana cyst

Spherical (5-10 um), 4 nuclei,

Lacks peripheral chromatin

Iodamoeba buetschlii trophozoites

- Sluggish, 8-20 um, large central karyosome

- Vacuolated, achromatic vacuoles

Iodamoeba buetschlii cyst

- 5-20 um, single nucleus

- One large glycogen vacuole

Entamoeba polecki trophozoites

Entamoeba polecki cyst

Many small chromatid bodies with angular/pointed ends

Balantidium coli

40-200 um

Cilia on surface

Cytostome (arrow)

Bean-shaped macronucleus

Cysts not often seen

Non-pathogenic amebae should ALWAYS be reported becuase

a sign of fecal-oral contamination.

Giardia duodenalis trophozoite

- Pear-shaped organisms

- 12-15 μm (range: 10-20 μm)

- 2 anteriorly-placed nuclei and 8 flagella

Giardia duodenalis cyst

- Ovoid to ellipsoid

- 11-14 μm (range: 8-19 μm).

- Immature cysts = 2 nuclei vs. mature cysts with 4 nuclei

- Intracytoplasmic fibrils visible

Trichomonas vaginalis trophozoite (NO Cyst stage)

- 7-30 μm long

- 5 flagella (4 anterior + 1 posterior)

- Large nucleus at wider/anterior end (contains chromatin granules and small karyosome)

- Cytoplasm with many granules
- pear shaped

Taenia’s proglottid function

absorb nutrients following past by

Taenia’s scolex function

Attaches to the intestines of the definitive host

Taenia spp. egg

characteristic radiating shell

Taenia saginata

four large suckers and lack of rostellum or rostellar hooks

proglottid: >14 branches (range 12-30);motile

taenia solium

four large suckers and rostellum containing two rows of hooks.

proglottid: 7-13 branches

Echinococcus spp.

Hydatid brood capsule with protoscolices

‘Hydatid sand’
Refractile hooklets

Diphyllobothriid worm proglottids

Width > length compared to Taenia

Diphyllobothriid worm eggs

55-65 x 38-42 micrometer

Smaller than Fasciola & Paragonimus eggs

Dipylidium caninum proglottid

10-70cm
“cucumber seed” when wet or “dried grain of rice”

Dipylidium caninum

Armed rostellum

Four suckers

Dipylidium caninum egg pocket

– Round

– Thin shelled

– Oncosphere with six hooklets

Enterobius vermicularis (pinworm)

Adults:

• 2.5 x 0.1-0.2 mm (male)

• 8-13 x 0.3-0.5 mm (female)

Males: blunt posterior end with a single spicule vs. Females: long pointed tail

Enterobius vermicularis (pinworm) microscopic

Enterobius vermicularis eggs

Trichuris trichiura (whipworm) Unembryonated egg

thick wall, with hyaline polar plugs

adult Trichuris trichiura (whipworm)

30-50mm long

Capillaria philippinensis

resemble Trichuris trichiura (whipworm)

smaller with thick/striated shell, less prominent polar plugs

Unfertilized Ascaris lumbricoides egg

Charateristic mammalated (nodulated呈结节状的)outer shell

fertilized Ascaris lumbricoides egg

Charateristics mammalated (nodulated呈结节状的)outer shell

Decorticated (losing outer bumpy layer) egg of Ascaris lumbricoides

still fertilized egg
potentially infective if embryonated

Necator americanus

cutting plate

Ancylostoma duodenale

teeth

Stool culture with Larvae glide around of Strongyloides sterocolis

Strongyloides eggs

folded inside

Strongyloides L1 rhabditiform larvae

Prominent genital primordium (blue arrow)

Rhabditoid esophagus (red arrow)

Short buccal canal (green arrow)

Strongyloides L3 FILARIFORM larvae

notched tail

Adult female Strongyloides in Biopsy

Encysted Trichinella Larvae in Muscle Tissue

Anisakis in fish tissue