PARASITOLOGY - Parasite Identification Flashcards
Why is parasite identification so important?
To treat the animal appropriately
To know where the parasite came from
To limit the spread of the parasite
What is parasitological diagnosis of a parasite?
Parasitological diagnosis is the diagnosis of a parasite based on the morphological characteristics of the parasite
What is immunological diagnosis of a parasite?
Immunological diagnosis is diagnosis of a parasite based on the presence of specific antibodies and antigens
What is molecular diagnosis of a parasite?
Molecular diagnosis is the diagnosis of a parasite based on PCR testing
Which two samples can you collect for parasite identification?
Faecal sample
Blood sample
Which diagnostic technique can be used to identify helminth eggs using a faecal sample when the helminth is fecund?
A direct smear
List four examples of nematode eggs commonly found in the faeces of cats and dogs
Toxacara canis/cati eggs
Strongyle eggs
Toxascaris leonina eggs
Trichuris eggs
Describe the appearance of Toxacara canis/cati eggs
Toxacara canis/cati eggs have a thick, rough, pitted egg shell
How would you identify the specific species of Strongyle as all species of Strongyle have identical egg morphologies?
To identify specific species of strongyle, you should culture the eggs in the lab, allowing them to hatch and develop into L3 larvae. The morphological features of the L3 larvae can then be examined to identify the species
Describe the appearance of Toxascaris leonina eggs
Toxascaris leonina eggs have a thick, smooth egg shell
What is the distinctive feature of Trichuris eggs?
Bipolar plugs
Which diagnostic technique can be used to concentrate helminth eggs?
Flotation
Describe how flotation is used as a diagnostic technique
The faecal sample is mixed into a saturated salt solution which allows the eggs to float to the surface for easier identification
Which two species of hookworm require culture to identify due to their similar egg morpholgies?
Ancylostoma caninum
Uncinaria stenocephala
What is the key clinical sign that can be used to identify Ancylostoma caninum?
Anaemia
Which diagnostic technique can be used to quantify helminth eggs?
McMaster slide
Describe how a McMaster slide is used to quantify helminth eggs
- Mix the faecal sample into a saturated salt solution
- Transfer a small amount of solution into each chamber of the McMaster slide
- Allow the parasite eggs to float to the surface and settle on the grids
- Using a microscope, count the number of eggs within the grids
- Multiply the number of eggs counted by a specific factor, determined by the size of the McMaster slide grid and the dilution factor used, this gives an estimate of the number of eggs per gram of faeces
Which diagnostic technique can be used to identify helminth larvae within a faecal sample?
Baermann technique
Which nematode is the baermann technique often used to detect in small animals?
Angiostrongylus vasorum
Which nematode is the baermann technique often used to detect in large animals?
Dictyocaulus viviparus
Which two diagnostic techniques can be used to detect helminth antigens within a faecal sample?
ELISA
Dipstick
Which diagnostic technique can be used to detect helminth DNA within a faecal sample?
PCR
Which two diagnostic techniques can be used to identify helminths using a blood sample?
Blood smear and staining
Serological tests
Which nematode is blood smears and staining often used to detect in small animals?
Microfilariae of Dirofilaria
Which stain is used to detect the microfilariae of Dirofilaria?
Giesma stain
Which nematode is serological tests often used to detect in small animals?
Angiostronglus vasorum
Why is the faecal egg count reduction test (FECRT) commonly used for helminth identification in large animals?
Faecal egg count reduction test (FECRT) measures the level of anthelmintic resistance within a helminth population
What is the characteristic appearance of a placenta infected with Toxoplasma gondii?
Bright red cotyledons with central white necrotic foci
What are the three methods that can be used to diagnose Toxoplasma gondii infection?
Antigen test on foetal fluids or pre-colostrum lamb serum
Immunohistochemistry
PCR on placental tissue
Why is IgM antibody detection so important when diagnosing Toxoplasma gondii?
IgM antibodies are produced early in the immune response with their presence suggesting recent exposure and first-time infection with Toxoplasma gondii
How is the Giardia protozoa diagnosed?
Giardia is diagnosed through concentrating a solid faecal sample using flotation to identify Giardia cysts using the microscope, in combination with an ELISA snap test
When you collect a soft faecal sample infected with Giardia and concentrate it using flotation, would you still identify Giardia cysts under the microscope?
No, you would identify Giardia trophozoites
How is Cryptosporiduim parvum typically diagnosed?
Cryptosporiduim parvum is typically diagnosed through concentrating a faecal sample using flotation to identify oocysts using the microscope
Which specialist stain is used to improve detection of Cryptosporiduim parvum oocysts?
Ziehl-Nielson stain
Which two diagnostic tests can be used to identify Babesia infection?
PCR
Identify Babesia on a blood smear
What are the two forms of Leishmania infection?
Cutaneous Leishmania
Visceral Leishmania
Which three diagnostic tests can be used to diagnose cutaneous Leishmania?
PCR
Identify Leismania amastigotes in macrophages on skin biopsy
Identify Leismania amastigotes in macrophages on blood smear
Which three diagnostic tests can be used to diagnose visceral Leishmania?
PCR
Identify Leismania amastigotes in macrophages on bone marrow biopsy
Identify Leismania amastigotes in macrophages on blood smear
Why is it so important to differentiate between species of parasite?
Because some species of parasite are zoonotic
