Diagnosis of Parasites

Question 1

why is diagnosis of parasites important (4)

Answer 1

1. what is the animal infected with
2. properly treat animal
3. understand where the infection came from
4. limit spread of infection

Question 2

what are the 3 areas of diagnosis

Answer 2

1. parasitological: based on morphological characteristics of the parasite
2. immunological: antigens, antibodies (less specific; long lasting so don’t indicate active infection just exposure)
3. molecular: PCR

Question 3

what does the diagnostic test need to be (3)

Answer 3

1. sensitive: identify infected animals
2. specific: distinguish between infections
3. reliable: consistent in different labs at different times

Question 4

what are samples used to diagnose parasites

Answer 4

blood or stool sample

Question 5

what types of worms are diagnosed by detection of eggs in stool

Answer 5

GI worms

Question 6

what are McMasters slides

Answer 6

quantitative method allows counting of eggs per gram of feces

Question 7

what are nematode eggs in dog/cat fecal specimens

Answer 7

Toxacaris leonia - smooth egg shell

Toxocara canis/cati - rough pitted egg shell

Strongyle egg

Trichuris

Question 8

why would nematode larvae need to be cultured from feces

Answer 8

if eggs of two species are identical (canine hookworms)

Question 9

why do some worm eggs require bacteria for hatching

Answer 9

Trichuris eggs

gut bacteria and worm relationship –> no bacteria = reduced hatching rate

Question 10

how are angiostrongylus vasorum larvae deteced in feces and what stage

Answer 10

smear, flotation or Baermann concentraion

L1

Question 11

what are examples of parasite antigen or DNA that can be deteced in stool samples

Answer 11

tapeworms

Echinococcus granulosus granulosus and Taenia species

Question 12

what species can be deteced in blood smears

Answer 12

dirofilaria species –> microfilaria

Question 13

what are serological tests for worms

Answer 13

antibody = measure of exposure

antigen = current infection

useful for Dirofilaria immitis (heartworm)

Question 14

why are antigen test alone not useful for heartworm infected cats

Answer 14

antigen test only detecs sexually mature female worms

cats often have few worms and often sexually immature

need antibody tests along with Ag test

Question 15

what are examples of protozoan parasites that can be diagnosed in the feces as cystic form

Answer 15

Toxoplasma gondii

cryptosporidium parvum

neospora caninum

giardia

Question 16

how are cryptosporidium detected

Answer 16

difficult to detect in unstained fecal samples due to small size

Ziehl Nielsen (acid fast)