Ectoparasite Diagnostic Tests Flashcards
Steps for diagnosis of ectoparasites
- Know which parasite(s) you are looking for
○ Based on host species, history, clinical signs - Carry out appropriate test(s)
- Carry out test correctly and take adequate samples from representative areas
- Examine the sample systematically to find the parasite
- Identify the parasite
Which tests are appropriate for fleas?
Coat brushing onto paper (+/- wet paper test)
NO MICROSCOPY
Which tests are appropriate for Lice?
Coat brushing onto paper OR liquid paraffin
Unstained acetate tape strip
Trichograms for eggs
Microscopy only used to identify species
Which tests are appropriate for Surface mites?
Coat brushings/combings into liquid paraffin on slide
Ear wax into liquid paraffin on slide
Superficial skin scrape into liquid paraffin
Unstained acetate tape strip
Trichogram (egg on hair) for Cheyletiella
Microscopy generally required
Which tests are appropriate for Burrowing Mites?
Deep skin scrape into liquid paraffin
Hair pluck (for demodex)
Acetate impression smears of squeezed skin (new technique)
MICROSCOPY ALWAYS REQUIRED
Which ectoparasites are identifiable with coat brushing onto paper?
Fleas
Lice
Which ectoparasites are identifiable with coat brushing into liquid paraffin onto slide?
Lice
Surface mites (Cheyletiella)
Which ectoparasites are identifiable with unstained acetate strip?
Lice
Surface mites (Cheyletiella and Neotrombicula)
Which ectoparasites are identifiable with superficial skin scrapings?
Surface mites (Cheyletiella and Neotrombicula)
Which ectoparasites are identifiable with deep skin scrapings?
Burrowing mites
Which ectoparasites are identifiable with hair plucks (trichograms)?
Lice eggs
Surface mite eggs (Cheyletiella)
Demodex
Examples of serology tests
Psoroptes antibody serology
Sarcoptes IgG serology
Flea IgE serology
Psoroptes Antibody Serology
Sheep Scab
Detects host antibodies to recombinant mite antigen
Can detect sheep scab infestation within 2 weeks of contact
* Potentially before clinical signs
Potential for false positives (from previously resolved infections)
Sarcoptes IgG Serology
False -ves
* Takes 1 month to seroconvert
False +ves
* Occasional cross reaction with anti-housedust mite antibodies in environmental atopics
Flea IgE Serology
Detects flea allergy/hypersensitivity NOT infestation
Detects type I hypersensitivity (NOT IV)
Tips for sampling
Select primary lesion if possible
Take multiple samples
Examine samples in LP under coverskip
Don’t make preparation too think
View area systematically
view on x4-10 with condenser diaphragm partially closed
Look at samples in-house
Tips for deep scrapings
Clip hair very short
Squeeze skin
scrape until capillary bleeding seen
May need biopsy if skin is thickened
Tips for Psoroptes sampling
Superficial scrapes at leading edge of lesion
How to identify insect
3 body parts
* Head
* Thorax
* Abdomen
3 pairs of legs on adults
* attached to thorax
How to identify Flies
3 body parts
* Head
* Thorax
* Abdomen
3 pairs of legs on adults
* attached to thorax
+ WINGS
How to identify Fleas
3 body parts
* Head
* Thorax
* Abdomen
3 pairs of legs on adults
* attached to thorax
+ Laterally flattened
+ Powerful legs
+ NO WINGS
How to identify Lice
3 body parts
* Head
* Thorax
* Abdomen
3 pairs of legs on adults
* attached to thorax
+ Dorsoventrally flattened
+ NO WINGS
Chewing/biting lice
Head is wider than thorax
Sucking lice
Head is narrower than thorax
