4- Diagnostic approach to common ectoparasites seen in practice

Question 1

How do you diagnose fleas?

Answer 1

Physical exam
Coat brushing/comb
Wet paper test

Question 2

How do you diagnose lice

Answer 2

Coat brushing/ comb
unstained acetate tape strip

Question 3

When sampling which lesion should you sample?

Answer 3

Primary lesion if possible

Question 4

How do you diagnose surface mites

Answer 4

coat brushings/ combings
ear wax into liquid paraffin on slide
superficial skin scraping into LP
unstained acetate tape strip
Microscopy generally required

Question 5

How do you diagnose deep mites

Answer 5

Deep skin scraping into LP
demodex= hair pluck
microscopy always required

Question 6

How many legs do ticks have?

Answer 6

8 legs

Question 7

T/F Lice are dorsoventrally flattened

Answer 7

True

Question 8

What insect is laterally flattened

Answer 8

Fleas

Question 9

Name the 2 types of lice & how you distinguish between them

Answer 9

Chewing - head wider than thorax
Sucking - Head narrower than thorax

Question 10

Name the 2 types of mites

Answer 10

Surface
Burrowing

Question 11

What is the mite that is cigar-shaped?

Answer 11

Demodex

Question 12

T/F Lice are species specific

Answer 12

True

Question 13

What is psoroptes?

Answer 13

Surface mite

Question 14

Do you need to use microscopy when diagnosing lice

Answer 14

they are visible with naked eye
microscopy needed to assess if chewing/sucking louse +/- to speciate

Question 15

Which ectoparasites are found above skin surface

Answer 15

fleas
lice
surface mites

Question 16

Describe how Psoroptes antibody serology works

Answer 16

detects host antibodies to recombinant mite antigen
can detect sheep scab infestation within 2 weeks of contact
potential for false positives from previous resolved infection

Question 17

How many samples should you take when investigating ectoparasites

Answer 17

minimum x6 skin scrapings

Question 18

When looking at mites with microscopy what settings to use

Answer 18

View on x4-10 with condenser diaphragm partially closed (+/- lower condenser) –> reduce light –> increase contrast of parasites

Question 19

Describe how to perform a deep skin scraping

Answer 19

Clip hair very short
Squeeze skin – constantly/ intermittently
Scrape until capillary bleeding seen

Question 20

Describe how you would test for psoroptes

Answer 20

take superficial scrapes at leading edge of lesion

Question 21

What is psoroptes

Answer 21

sheep scab
is a surface mite

Question 22

What species does Felicola sp affect

Answer 22

is a chewing louse
cat

Question 23

What species does Damalinia (Bovicola) spp affect

Answer 23

Horse, cattle, sheep, goats
is a chewing louse

Question 24

What species does Trichodectes sp affect

Answer 24

dog
is a chewing louse

Question 25

What species does Haematopinus spp affect

Answer 25

cattle, pig, horses
is a sucking louse

Question 26

What species does Linognathus spp affect

Answer 26

cow, sheep, goats, dogs
is a sucking louse