Parasitology - general info Flashcards
What are pseudo-parasites
- false parasites
- Organic and inorganic substances which are similar to the propagation stages of parasites (eggs, cysts, larvae)
- divided into: Non-parasitic substances & Non-specific parasitic objects
What are the “Non-parasitic substances”?
- Plant fibers, hair of animals
- Pollen grain
- Cells of plants
- Mucosal cells
- Fat droplets
- Muscle fibers
- Fungal spores
- Air bubble
What are the “Non-specific parasitic objects”?
- Monocystis sp. – protozoa from earthworms
- Eggs and larvae of parasites from another host by coprophagiae (pig ingest faces of poultry, dogs usually ingest faces of ruminants)
- Eggs, cysts and larvae of free-living (non-parasitic) animals
Picture of the “Non-parasitic substances” and the
“Non-specific parasitic objects”
- Air bubble – A1
- Cells of plants – B1
- Fungal spores – C (Alternaria)
- Monocystis sp. – protozoa from earthworms – D
Picture of pollen grains:
(Non-parasitic substance)
The morphology eggs - The differential diagnosis of helminths eggs is based on these basic criteria:
- Size
- shape
- structure of shells
- internal structure
- color (the additional one)
What are the different sizes of helminths eggs:
- Small eggs: less than 60 μm in length
- Medium eggs: 60.1 - 100 μm in length
- Large eggs: 100.1 - 200 μm in length
- Extra-large eggs: larger than 200.1 μm in length
mention different Helminths eggs and sizes:
small eggs:
- Taenia spp.
medium eggs:
- Trichuris spp.
- Ascaris spp.
- Trichostrongylidae
large eggs:
- Fasciola hepatica
extra large eggs:
- Nematodirus spp.
Shape of Trematode eggs:
- Oval, symmetrical – Fasciola, Paramphistomum
- Oval, asymmetrical – Dicrocoelium
Shape of Cestode eggs:
- Oval – Pseudophyllidae, Hymenolepididae
- Roundish – Taeniidae
- 3, 4, 5 angulate – Anoplocephalidae
- In cocoons – Dipylidium, Raillietina
Shape of Nematode eggs:
- Ovoid, oval – Strongylidae
- Spherical, subspherical – Ascaris, Parascaris, Toxocara
- Lemon shaped – Trichuris
- Barreled – Capillaria
- Oval – asymmetrical – Oxyuridae
Shape of Acantocephalan eggs:
- Oval – Macracanthorhynchus, Polymorphus
Structure of Shells - Trematodes:
- two thin shells
- an operculum at one pole – lack at Schistosoma spp.
Structure of Shells - Cestodes:
Pseudo-phyllida – two thin shells with operculum at one pole and a small button at the other
Cyclo-phyllidea – three layers:
- The superficial (homogeneous) – is thin and water-permeable
- Middle (lipoid) layer – is thick and not water-permeable
- Internal (embryophore) layer – covers the embryo, is very thin and in family Anoplocephalidae is pea-shaped (pyriform apparatus)
Structure of Shells - Nematodes:
three layers:
- Protein layer (external) – smooth, rough (Parascaris), uniformly and distinctively patterned (Toxocara)
- Chitin layer (middle) – smooth, homogenous, transparent
- Vitelline layer (internal) – in direct contact with protoplasm or embryo
Structure of Shells - Acantocephalan:
- Three layers, as at the nematodes:
- Protein layer (external) – smooth, rough, uniformly and distinctively patterned
- Chitin layer (middle) – smooth, homogenous, transparent
- Vitelline layer (internal) – in direct contact with protoplasm or embryo
Internal structure of Trematode eggs:
- Unembryonated
- Embryonated
Internal structure of Cestode eggs:
- PSEUDOPHYLLIDEA – Unembryonated
- CYCLOPHYLLIDEA – Embryonated
(oncosphere) – 3 pairs of hooks, so called hexacanth embryo
Internal structure of Nematode eggs:
Unembryonated:
- single cell is homogenous (Toxocara, Toxasccaris)
- finely granulated protoplasm (Trichuris, Capillaria)
- morula with 4-8 blastomers (Ancylostoma, Uncinaria, Nematodirus, Syngamus)
- morula with more 16 blastomers (Trichostrongylidae)
Embryonated:
- larva in the first stage – L1 (Strongyloides, Metastrongylus, Spirurida)
Internal structure of Acantocephalan eggs:
- Embryonated (acantor)
Color (additional criteria):
- Brown: Ascaris, Parascaris, Dicrocoelium, Macracanthorhynchus
- Reddish-brown: Trichuris
- Dark brown: Toxocara
- Light brown/grey: Strongylida
- Yellow: Fasciola
- Light green: Capillaria
- Colorless, transparent: Strongyloides, Oxyuris
Direct microscopic investigation of feces:
- Direct smear – suitable for a rapid examination.
- A small quantity of faeces is placed on a slide, mixed with a drop of water, spread out covered with a slip and examined directly.
Flotation method is a:
- Qualitative concentration method
flotation methods depend on:
- mixing of the faecal sample with a liquid whose specific gravity greater than the parasite.
